| 7-Nitroindazole | The risk or severity of adverse effects can be increased when Barbital is combined with 7-Nitroindazole. | Experimental |
| Acebutolol | Barbital may increase the hypotensive activities of Acebutolol. | Approved |
| Acenocoumarol | The metabolism of Acenocoumarol can be increased when combined with Barbital. | Approved |
| Acepromazine | The risk or severity of adverse effects can be increased when Barbital is combined with Acepromazine. | Approved, Vet Approved |
| Aceprometazine | The risk or severity of adverse effects can be increased when Barbital is combined with Aceprometazine. | Approved |
| Acetaminophen | The metabolism of Acetaminophen can be increased when combined with Barbital. | Approved |
| Acetazolamide | Barbital may increase the hypotensive activities of Acetazolamide. | Approved, Vet Approved |
| Adipiplon | The risk or severity of adverse effects can be increased when Barbital is combined with adipiplon. | Investigational |
| Agomelatine | The risk or severity of adverse effects can be increased when Barbital is combined with Agomelatine. | Approved, Investigational |
| Aldesleukin | Barbital may increase the hypotensive activities of Aldesleukin. | Approved |
| Alfaxalone | The risk or severity of adverse effects can be increased when Barbital is combined with Alfaxalone. | Vet Approved |
| Alfentanil | The risk or severity of adverse effects can be increased when Alfentanil is combined with Barbital. | Approved, Illicit |
| Aliskiren | Barbital may increase the hypotensive activities of Aliskiren. | Approved, Investigational |
| Allopregnanolone | The risk or severity of adverse effects can be increased when Barbital is combined with Sage 547. | Investigational |
| Alphacetylmethadol | The risk or severity of adverse effects can be increased when Barbital is combined with Alphacetylmethadol. | Experimental, Illicit |
| Alprazolam | The risk or severity of adverse effects can be increased when Alprazolam is combined with Barbital. | Approved, Illicit, Investigational |
| Alprenolol | The serum concentration of Alprenolol can be decreased when it is combined with Barbital. | Approved, Withdrawn |
| Ambroxol acefyllinate | The serum concentration of Ambroxol acefyllinate can be decreased when it is combined with Barbital. | Experimental |
| Amifostine | Barbital may increase the hypotensive activities of Amifostine. | Approved, Investigational |
| Amiloride | Barbital may increase the hypotensive activities of Amiloride. | Approved |
| Amineptine | The metabolism of Amineptine can be increased when combined with Barbital. | Illicit, Withdrawn |
| Aminophylline | The serum concentration of Aminophylline can be decreased when it is combined with Barbital. | Approved |
| Amiodarone | Barbital may increase the hypotensive activities of Amiodarone. | Approved, Investigational |
| Amisulpride | The risk or severity of adverse effects can be increased when Barbital is combined with Amisulpride. | Approved, Investigational |
| Amitriptyline | The metabolism of Amitriptyline can be increased when combined with Barbital. | Approved |
| Amlodipine | Barbital may increase the hypotensive activities of Amlodipine. | Approved |
| Amobarbital | The risk or severity of adverse effects can be increased when Amobarbital is combined with Barbital. | Approved, Illicit |
| Amoxapine | The risk or severity of adverse effects can be increased when Barbital is combined with Amoxapine. | Approved |
| Amperozide | The risk or severity of adverse effects can be increased when Barbital is combined with Amperozide. | Experimental |
| Amphotericin B | Barbital may increase the hypotensive activities of Amphotericin B. | Approved, Investigational |
| Amrinone | The metabolism of Amrinone can be increased when combined with Barbital. | Approved |
| Amyl Nitrite | Barbital may increase the hypotensive activities of Amyl Nitrite. | Approved |
| Apomorphine | Barbital may increase the hypotensive activities of Apomorphine. | Approved, Investigational |
| Apraclonidine | Barbital may increase the hypotensive activities of Apraclonidine. | Approved |
| Aripiprazole | The risk or severity of adverse effects can be increased when Aripiprazole is combined with Barbital. | Approved, Investigational |
| Arotinolol | The serum concentration of Arotinolol can be decreased when it is combined with Barbital. | Approved |
| Arsenic trioxide | Barbital may increase the hypotensive activities of Arsenic trioxide. | Approved, Investigational |
| Articaine | The risk or severity of adverse effects can be increased when Barbital is combined with Articaine. | Approved |
| Asenapine | The risk or severity of adverse effects can be increased when Barbital is combined with Asenapine. | Approved |
| Atenolol | Barbital may increase the hypotensive activities of Atenolol. | Approved |
| Azelastine | Barbital may increase the central nervous system depressant (CNS depressant) activities of Azelastine. | Approved |
| Azelastine | The risk or severity of adverse effects can be increased when Barbital is combined with Azelastine. | Approved |
| Azelnidipine | The metabolism of Azelnidipine can be increased when combined with Barbital. | Approved |
| Azilsartan medoxomil | Barbital may increase the hypotensive activities of Azilsartan medoxomil. | Approved |
| Azimilide | The metabolism of Azimilide can be increased when combined with Barbital. | Investigational |
| Baclofen | The risk or severity of adverse effects can be increased when Barbital is combined with Baclofen. | Approved |
| Barnidipine | The metabolism of Barnidipine can be increased when combined with Barbital. | Approved |
| Befunolol | The serum concentration of Befunolol can be decreased when it is combined with Barbital. | Experimental |
| Benazepril | Barbital may increase the hypotensive activities of Benazepril. | Approved, Investigational |
| Bendroflumethiazide | Barbital may increase the orthostatic hypotensive activities of Bendroflumethiazide. | Approved |
| Benidipine | The metabolism of Benidipine can be increased when combined with Barbital. | Approved |
| Benperidol | The risk or severity of adverse effects can be increased when Barbital is combined with Benperidol. | Investigational |
| Benzocaine | The risk or severity of adverse effects can be increased when Benzocaine is combined with Barbital. | Approved |
| Benzyl alcohol | The risk or severity of adverse effects can be increased when Barbital is combined with Benzyl alcohol. | Approved |
| Bepridil | The metabolism of Bepridil can be increased when combined with Barbital. | Approved, Withdrawn |
| Betaxolol | Barbital may increase the hypotensive activities of Betaxolol. | Approved |
| Bevantolol | The serum concentration of Bevantolol can be decreased when it is combined with Barbital. | Approved |
| Bisoprolol | Barbital may increase the hypotensive activities of Bisoprolol. | Approved |
| Bopindolol | The serum concentration of Bopindolol can be decreased when it is combined with Barbital. | Approved |
| Bortezomib | Barbital may increase the hypotensive activities of Bortezomib. | Approved, Investigational |
| Bretylium | Barbital may increase the hypotensive activities of Bretylium. | Approved |
| Brexpiprazole | The risk or severity of adverse effects can be increased when Barbital is combined with Brexpiprazole. | Approved |
| Brimonidine | The risk or severity of adverse effects can be increased when Barbital is combined with Brimonidine. | Approved |
| Brimonidine | Brimonidine may increase the central nervous system depressant (CNS depressant) activities of Barbital. | Approved |
| Bromazepam | The risk or severity of adverse effects can be increased when Barbital is combined with Bromazepam. | Approved, Illicit |
| Bromocriptine | Barbital may increase the hypotensive activities of Bromocriptine. | Approved, Investigational |
| Brompheniramine | The risk or severity of adverse effects can be increased when Barbital is combined with Brompheniramine. | Approved |
| Brotizolam | The risk or severity of adverse effects can be increased when Barbital is combined with Brotizolam. | Approved, Withdrawn |
| Bucindolol | The serum concentration of Bucindolol can be decreased when it is combined with Barbital. | Investigational |
| Bufuralol | The serum concentration of Bufuralol can be decreased when it is combined with Barbital. | Experimental, Investigational |
| Bumetanide | Barbital may increase the hypotensive activities of Bumetanide. | Approved |
| Bupivacaine | The risk or severity of adverse effects can be increased when Bupivacaine is combined with Barbital. | Approved, Investigational |
| Bupranolol | The serum concentration of Bupranolol can be decreased when it is combined with Barbital. | Approved |
| Buprenorphine | Barbital may increase the central nervous system depressant (CNS depressant) activities of Buprenorphine. | Approved, Illicit, Investigational, Vet Approved |
| Buspirone | The risk or severity of adverse effects can be increased when Buspirone is combined with Barbital. | Approved, Investigational |
| Butabarbital | The risk or severity of adverse effects can be increased when Butabarbital is combined with Barbital. | Approved, Illicit |
| Butalbital | The risk or severity of adverse effects can be increased when Barbital is combined with Butalbital. | Approved, Illicit |
| Butethal | The risk or severity of adverse effects can be increased when Butethal is combined with Barbital. | Approved, Illicit |
| Butorphanol | The risk or severity of adverse effects can be increased when Butorphanol is combined with Barbital. | Approved, Illicit, Vet Approved |
| Canagliflozin | Barbital may increase the hypotensive activities of Canagliflozin. | Approved |
| Candesartan | Barbital may increase the hypotensive activities of Candesartan. | Approved |
| Captopril | Barbital may increase the hypotensive activities of Captopril. | Approved |
| Carbamazepine | The risk or severity of adverse effects can be increased when Carbamazepine is combined with Barbital. | Approved, Investigational |
| Carbetocin | Barbital may increase the hypotensive activities of Carbetocin. | Approved |
| Carbinoxamine | The risk or severity of adverse effects can be increased when Barbital is combined with Carbinoxamine. | Approved |
| Carboxyamidotriazole | The metabolism of Cai can be increased when combined with Barbital. | Investigational |
| Carfentanil | The risk or severity of adverse effects can be increased when Barbital is combined with Carfentanil. | Illicit, Vet Approved |
| Carisoprodol | The risk or severity of adverse effects can be increased when Barbital is combined with Carisoprodol. | Approved |
| Carteolol | Barbital may increase the hypotensive activities of Carteolol. | Approved |
| Carvedilol | Barbital may increase the hypotensive activities of Carvedilol. | Approved, Investigational |
| Celiprolol | The serum concentration of Celiprolol can be decreased when it is combined with Barbital. | Approved, Investigational |
| Cetirizine | The risk or severity of adverse effects can be increased when Barbital is combined with Cetirizine. | Approved |
| Chloral hydrate | The risk or severity of adverse effects can be increased when Barbital is combined with Chloral hydrate. | Approved, Illicit, Vet Approved |
| Chloramphenicol | The metabolism of Barbital can be decreased when combined with Chloramphenicol. | Approved, Vet Approved |
| Chlordiazepoxide | The risk or severity of adverse effects can be increased when Chlordiazepoxide is combined with Barbital. | Approved, Illicit |
| Chlormezanone | The risk or severity of adverse effects can be increased when Chlormezanone is combined with Barbital. | Approved, Withdrawn |
| Chloroprocaine | The risk or severity of adverse effects can be increased when Chloroprocaine is combined with Barbital. | Approved |
| Chlorothiazide | Barbital may increase the orthostatic hypotensive activities of Chlorothiazide. | Approved, Vet Approved |
| Chlorotrianisene | The therapeutic efficacy of Chlorotrianisene can be decreased when used in combination with Barbital. | Withdrawn |
| Chlorphenamine | The risk or severity of adverse effects can be increased when Barbital is combined with Chlorphenamine. | Approved |
| Chlorpromazine | The risk or severity of adverse effects can be increased when Chlorpromazine is combined with Barbital. | Approved, Vet Approved |
| Chlorprothixene | The risk or severity of adverse effects can be increased when Chlorprothixene is combined with Barbital. | Approved, Withdrawn |
| Chlorthalidone | Barbital may increase the orthostatic hypotensive activities of Chlorthalidone. | Approved |
| Chlorzoxazone | The risk or severity of adverse effects can be increased when Barbital is combined with Chlorzoxazone. | Approved |
| Cilazapril | Barbital may increase the hypotensive activities of Cilazapril. | Approved |
| Cilnidipine | The metabolism of Cilnidipine can be increased when combined with Barbital. | Approved |
| Cinchocaine | The risk or severity of adverse effects can be increased when Cinchocaine is combined with Barbital. | Approved, Vet Approved |
| Cinnarizine | The metabolism of Cinnarizine can be increased when combined with Barbital. | Approved |
| Citalopram | The risk or severity of adverse effects can be increased when Barbital is combined with Citalopram. | Approved |
| Clemastine | The risk or severity of adverse effects can be increased when Barbital is combined with Clemastine. | Approved |
| Clevidipine | Barbital may increase the hypotensive activities of Clevidipine. | Approved |
| Clidinium | The risk or severity of adverse effects can be increased when Barbital is combined with Clidinium. | Approved |
| Clobazam | The risk or severity of adverse effects can be increased when Barbital is combined with Clobazam. | Approved, Illicit |
| Clofarabine | Barbital may increase the hypotensive activities of Clofarabine. | Approved, Investigational |
| Clomipramine | The metabolism of Clomipramine can be increased when combined with Barbital. | Approved, Vet Approved |
| Clonazepam | The risk or severity of adverse effects can be increased when Barbital is combined with Clonazepam. | Approved, Illicit |
| Clonidine | The risk or severity of adverse effects can be increased when Barbital is combined with Clonidine. | Approved |
| Clorazepate | The risk or severity of adverse effects can be increased when Clorazepate is combined with Barbital. | Approved, Illicit |
| Clozapine | The risk or severity of adverse effects can be increased when Clozapine is combined with Barbital. | Approved |
| Cocaine | The risk or severity of adverse effects can be increased when Cocaine is combined with Barbital. | Approved, Illicit |
| Codeine | The risk or severity of adverse effects can be increased when Codeine is combined with Barbital. | Approved, Illicit |
| Conivaptan | Barbital may increase the hypotensive activities of Conivaptan. | Approved, Investigational |
| Conjugated estrogens | The therapeutic efficacy of Conjugated Equine Estrogens can be decreased when used in combination with Barbital. | Approved |
| Cyclizine | The risk or severity of adverse effects can be increased when Barbital is combined with Cyclizine. | Approved |
| Cyclobenzaprine | The metabolism of Cyclobenzaprine can be increased when combined with Barbital. | Approved |
| Cyclosporine | The metabolism of Cyclosporine can be increased when combined with Barbital. | Approved, Investigational, Vet Approved |
| Cyproheptadine | The risk or severity of adverse effects can be increased when Barbital is combined with Cyproheptadine. | Approved |
| Dantrolene | The risk or severity of adverse effects can be increased when Barbital is combined with Dantrolene. | Approved |
| Dapagliflozin | Barbital may increase the hypotensive activities of Dapagliflozin. | Approved |
| Dapiprazole | The risk or severity of adverse effects can be increased when Dapiprazole is combined with Barbital. | Approved |
| Dapoxetine | The risk or severity of adverse effects can be increased when Barbital is combined with Dapoxetine. | Investigational |
| Darodipine | The metabolism of Darodipine can be increased when combined with Barbital. | Experimental |
| Deramciclane | The risk or severity of adverse effects can be increased when Barbital is combined with deramciclane. | Investigational |
| Desflurane | The risk or severity of adverse effects can be increased when Desflurane is combined with Barbital. | Approved |
| Desipramine | The metabolism of Desipramine can be increased when combined with Barbital. | Approved |
| Desloratadine | The risk or severity of adverse effects can be increased when Barbital is combined with Desloratadine. | Approved, Investigational |
| Desogestrel | The therapeutic efficacy of Desogestrel can be decreased when used in combination with Barbital. | Approved |
| Desvenlafaxine | The risk or severity of adverse effects can be increased when Barbital is combined with Desvenlafaxine. | Approved |
| Dexbrompheniramine | The risk or severity of adverse effects can be increased when Barbital is combined with Dexbrompheniramine. | Approved |
| Dexmedetomidine | The risk or severity of adverse effects can be increased when Dexmedetomidine is combined with Barbital. | Approved, Vet Approved |
| Dextromoramide | The risk or severity of adverse effects can be increased when Barbital is combined with Dextromoramide. | Experimental, Illicit |
| Dextropropoxyphene | The risk or severity of adverse effects can be increased when Dextropropoxyphene is combined with Barbital. | Approved, Illicit, Withdrawn |
| Dezocine | The risk or severity of adverse effects can be increased when Dezocine is combined with Barbital. | Approved |
| Diazepam | The risk or severity of adverse effects can be increased when Diazepam is combined with Barbital. | Approved, Illicit, Vet Approved |
| Diclofenamide | Barbital may increase the hypotensive activities of Diclofenamide. | Approved |
| Dicoumarol | The metabolism of Dicoumarol can be increased when combined with Barbital. | Approved |
| Dienestrol | The therapeutic efficacy of Dienestrol can be decreased when used in combination with Barbital. | Approved |
| Dienogest | The therapeutic efficacy of Dienogest can be decreased when used in combination with Barbital. | Approved |
| Diethylstilbestrol | The therapeutic efficacy of Diethylstilbestrol can be decreased when used in combination with Barbital. | Approved |
| Difenoxin | The risk or severity of adverse effects can be increased when Barbital is combined with Difenoxin. | Approved, Illicit |
| Dihydrocodeine | The risk or severity of adverse effects can be increased when Barbital is combined with Dihydrocodeine. | Approved, Illicit |
| Dihydroetorphine | The risk or severity of adverse effects can be increased when Dihydroetorphine is combined with Barbital. | Experimental, Illicit |
| Dihydromorphine | The risk or severity of adverse effects can be increased when Barbital is combined with Dihydromorphine. | Experimental, Illicit |
| Diltiazem | Barbital may increase the hypotensive activities of Diltiazem. | Approved |
| Dimenhydrinate | The risk or severity of adverse effects can be increased when Barbital is combined with Dimenhydrinate. | Approved |
| Dinutuximab | Barbital may increase the hypotensive activities of Dinutuximab. | Approved |
| Diphenhydramine | The risk or severity of adverse effects can be increased when Diphenhydramine is combined with Barbital. | Approved |
| Diphenoxylate | The risk or severity of adverse effects can be increased when Diphenoxylate is combined with Barbital. | Approved, Illicit |
| Dipyridamole | Barbital may increase the hypotensive activities of Dipyridamole. | Approved |
| Dosulepin | The metabolism of Dosulepin can be increased when combined with Barbital. | Approved |
| Doxazosin | Barbital may increase the hypotensive activities of Doxazosin. | Approved |
| Doxepin | The metabolism of Doxepin can be increased when combined with Barbital. | Approved |
| Doxycycline | The serum concentration of Doxycycline can be decreased when it is combined with Barbital. | Approved, Investigational, Vet Approved |
| Doxylamine | Doxylamine may increase the central nervous system depressant (CNS depressant) activities of Barbital. | Approved, Vet Approved |
| Dronabinol | Dronabinol may increase the central nervous system depressant (CNS depressant) activities of Barbital. | Approved, Illicit |
| Droperidol | Droperidol may increase the central nervous system depressant (CNS depressant) activities of Barbital. | Approved, Vet Approved |
| Drospirenone | The therapeutic efficacy of Drospirenone can be decreased when used in combination with Barbital. | Approved |
| Drotebanol | The risk or severity of adverse effects can be increased when Barbital is combined with Drotebanol. | Experimental, Illicit |
| Duloxetine | The risk or severity of adverse effects can be increased when Barbital is combined with Duloxetine. | Approved |
| Dyclonine | The risk or severity of adverse effects can be increased when Dyclonine is combined with Barbital. | Approved |
| Dyphylline | The serum concentration of Dyphylline can be decreased when it is combined with Barbital. | Approved |
| Ecgonine | The risk or severity of adverse effects can be increased when Barbital is combined with Ecgonine. | Experimental, Illicit |
| Ecopipam | The risk or severity of adverse effects can be increased when Barbital is combined with Ecopipam. | Investigational |
| Efavirenz | The risk or severity of adverse effects can be increased when Barbital is combined with Efavirenz. | Approved, Investigational |
| Efonidipine | The metabolism of Efonidipine can be increased when combined with Barbital. | Approved |
| Eltanolone | The risk or severity of adverse effects can be increased when Barbital is combined with Pregnanolone. | Investigational |
| Empagliflozin | Barbital may increase the hypotensive activities of Empagliflozin. | Approved |
| Enalapril | Barbital may increase the hypotensive activities of Enalapril. | Approved, Vet Approved |
| Enalaprilat | Barbital may increase the hypotensive activities of Enalaprilat. | Approved |
| Enflurane | The risk or severity of adverse effects can be increased when Enflurane is combined with Barbital. | Approved, Vet Approved |
| Entacapone | The risk or severity of adverse effects can be increased when Barbital is combined with Entacapone. | Approved, Investigational |
| Eperisone | The metabolism of Eperisone can be increased when combined with Barbital. | Approved, Investigational |
| Eplerenone | Barbital may increase the hypotensive activities of Eplerenone. | Approved |
| Epoprostenol | Barbital may increase the hypotensive activities of Epoprostenol. | Approved |
| Eprosartan | Barbital may increase the hypotensive activities of Eprosartan. | Approved |
| Escitalopram | The risk or severity of adverse effects can be increased when Barbital is combined with Escitalopram. | Approved, Investigational |
| Esmirtazapine | The metabolism of Esmirtazapine can be increased when combined with Barbital. | Investigational |
| Esmolol | Barbital may increase the hypotensive activities of Esmolol. | Approved |
| Estazolam | The risk or severity of adverse effects can be increased when Estazolam is combined with Barbital. | Approved, Illicit |
| Estradiol | The therapeutic efficacy of Estradiol can be decreased when used in combination with Barbital. | Approved, Investigational, Vet Approved |
| Estramustine | The therapeutic efficacy of Estramustine can be decreased when used in combination with Barbital. | Approved |
| Estrogens, esterified | The therapeutic efficacy of Estrogens, esterified can be decreased when used in combination with Barbital. | Approved |
| Estrone sulfate | The therapeutic efficacy of Estrone sulfate can be decreased when used in combination with Barbital. | Approved |
| Eszopiclone | The risk or severity of adverse effects can be increased when Eszopiclone is combined with Barbital. | Approved |
| Etacrynic acid | Barbital may increase the hypotensive activities of Etacrynic acid. | Approved |
| Ethanol | Barbital may increase the central nervous system depressant (CNS depressant) activities of Ethanol. | Approved |
| Ethchlorvynol | The risk or severity of adverse effects can be increased when Ethchlorvynol is combined with Barbital. | Approved, Illicit, Withdrawn |
| Ethinyl Estradiol | The therapeutic efficacy of Ethinyl Estradiol can be decreased when used in combination with Barbital. | Approved |
| Ethosuximide | The risk or severity of adverse effects can be increased when Barbital is combined with Ethosuximide. | Approved |
| Ethotoin | The risk or severity of adverse effects can be increased when Barbital is combined with Ethotoin. | Approved |
| Ethyl biscoumacetate | The metabolism of Ethyl biscoumacetate can be increased when combined with Barbital. | Withdrawn |
| Ethyl carbamate | The risk or severity of adverse effects can be increased when Barbital is combined with Ethyl carbamate. | Withdrawn |
| Ethyl loflazepate | The risk or severity of adverse effects can be increased when Barbital is combined with Ethyl loflazepate. | Approved, Illicit |
| Ethylmorphine | The risk or severity of adverse effects can be increased when Ethylmorphine is combined with Barbital. | Approved, Illicit |
| Ethynodiol diacetate | The therapeutic efficacy of Ethynodiol diacetate can be decreased when used in combination with Barbital. | Approved |
| Etidocaine | The risk or severity of adverse effects can be increased when Barbital is combined with Etidocaine. | Approved |
| Etifoxine | The risk or severity of adverse effects can be increased when Barbital is combined with Etifoxine. | Withdrawn |
| Etizolam | The risk or severity of adverse effects can be increased when Barbital is combined with Etizolam. | Approved |
| Etomidate | The risk or severity of adverse effects can be increased when Etomidate is combined with Barbital. | Approved |
| Etonogestrel | The therapeutic efficacy of Etonogestrel can be decreased when used in combination with Barbital. | Approved, Investigational |
| Etoperidone | The risk or severity of adverse effects can be increased when Barbital is combined with Etoperidone. | Approved |
| Etorphine | The risk or severity of adverse effects can be increased when Barbital is combined with Etorphine. | Illicit, Vet Approved |
| Ezogabine | The risk or severity of adverse effects can be increased when Barbital is combined with Ezogabine. | Approved |
| Felbamate | The serum concentration of Barbital can be increased when it is combined with Felbamate. | Approved |
| Felodipine | Barbital may increase the hypotensive activities of Felodipine. | Approved, Investigational |
| Fencamfamine | The risk or severity of adverse effects can be increased when Fencamfamine is combined with Barbital. | Approved, Illicit, Withdrawn |
| Fendiline | The metabolism of Fendiline can be increased when combined with Barbital. | Withdrawn |
| Fenoldopam | Barbital may increase the hypotensive activities of Fenoldopam. | Approved |
| Fentanyl | The risk or severity of adverse effects can be increased when Fentanyl is combined with Barbital. | Approved, Illicit, Investigational, Vet Approved |
| Fexofenadine | The risk or severity of adverse effects can be increased when Barbital is combined with Fexofenadine. | Approved |
| Fimasartan | Barbital may increase the hypotensive activities of Fimasartan. | Approved |
| Flibanserin | The risk or severity of adverse effects can be increased when Barbital is combined with Flibanserin. | Approved |
| Fludiazepam | The risk or severity of adverse effects can be increased when Barbital is combined with Fludiazepam. | Approved, Illicit |
| Fluindione | The metabolism of Fluindione can be increased when combined with Barbital. | Investigational |
| Flunarizine | The risk or severity of adverse effects can be increased when Barbital is combined with Flunarizine. | Approved |
| Flunitrazepam | The risk or severity of adverse effects can be increased when Barbital is combined with Flunitrazepam. | Approved, Illicit |
| Fluoxetine | The risk or severity of adverse effects can be increased when Barbital is combined with Fluoxetine. | Approved, Vet Approved |
| Flupentixol | The risk or severity of adverse effects can be increased when Flupentixol is combined with Barbital. | Approved, Withdrawn |
| Fluphenazine | The risk or severity of adverse effects can be increased when Fluphenazine is combined with Barbital. | Approved |
| Flurazepam | The risk or severity of adverse effects can be increased when Flurazepam is combined with Barbital. | Approved, Illicit |
| Fluspirilene | The risk or severity of adverse effects can be increased when Barbital is combined with Fluspirilene. | Approved |
| Fluticasone propionate | The risk or severity of adverse effects can be increased when Barbital is combined with Fluticasone Propionate. | Approved |
| Fluvoxamine | The risk or severity of adverse effects can be increased when Fluvoxamine is combined with Barbital. | Approved, Investigational |
| Fosinopril | Barbital may increase the hypotensive activities of Fosinopril. | Approved |
| Fosphenytoin | The risk or severity of adverse effects can be increased when Barbital is combined with Fosphenytoin. | Approved |
| Fospropofol | The risk or severity of adverse effects can be increased when Barbital is combined with Fospropofol. | Approved, Illicit |
| Furosemide | Barbital may increase the hypotensive activities of Furosemide. | Approved, Vet Approved |
| Gabapentin | The risk or severity of adverse effects can be increased when Gabapentin is combined with Barbital. | Approved, Investigational |
| Gabapentin Enacarbil | The risk or severity of adverse effects can be increased when Barbital is combined with gabapentin enacarbil. | Approved |
| Gallopamil | The metabolism of Gallopamil can be increased when combined with Barbital. | Investigational |
| Gamma Hydroxybutyric Acid | The risk or severity of adverse effects can be increased when Gamma Hydroxybutyric Acid is combined with Barbital. | Approved, Illicit |
| Gepirone | The risk or severity of adverse effects can be increased when Barbital is combined with Gepirone. | Investigational |
| Gestodene | The therapeutic efficacy of Gestodene can be decreased when used in combination with Barbital. | Approved |
| Glutethimide | The risk or severity of adverse effects can be increased when Glutethimide is combined with Barbital. | Approved, Illicit |
| Griseofulvin | The serum concentration of Griseofulvin can be decreased when it is combined with Barbital. | Approved, Vet Approved |
| Guanfacine | The risk or severity of adverse effects can be increased when Barbital is combined with Guanfacine. | Approved, Investigational |
| Halazepam | The risk or severity of adverse effects can be increased when Halazepam is combined with Barbital. | Approved, Illicit, Withdrawn |
| Haloperidol | The risk or severity of adverse effects can be increased when Haloperidol is combined with Barbital. | Approved |
| Halothane | The risk or severity of adverse effects can be increased when Halothane is combined with Barbital. | Approved, Vet Approved |
| Heroin | The risk or severity of adverse effects can be increased when Heroin is combined with Barbital. | Approved, Illicit |
| Hexestrol | The therapeutic efficacy of Hexestrol can be decreased when used in combination with Barbital. | Withdrawn |
| Hexobarbital | The risk or severity of adverse effects can be increased when Hexobarbital is combined with Barbital. | Approved |
| Hydralazine | Barbital may increase the hypotensive activities of Hydralazine. | Approved |
| Hydrochlorothiazide | Barbital may increase the orthostatic hypotensive activities of Hydrochlorothiazide. | Approved, Vet Approved |
| Hydrocodone | Barbital may increase the central nervous system depressant (CNS depressant) activities of Hydrocodone. | Approved, Illicit |
| Hydroflumethiazide | Barbital may increase the orthostatic hypotensive activities of Hydroflumethiazide. | Approved |
| Hydromorphone | The risk or severity of adverse effects can be increased when Hydromorphone is combined with Barbital. | Approved, Illicit |
| Hydroxyzine | Hydroxyzine may increase the central nervous system depressant (CNS depressant) activities of Barbital. | Approved |
| Iloperidone | The risk or severity of adverse effects can be increased when Barbital is combined with Iloperidone. | Approved |
| Iloprost | Barbital may increase the hypotensive activities of Iloprost. | Approved, Investigational |
| Imidapril | Barbital may increase the hypotensive activities of Imidapril. | Investigational |
| Imipramine | The metabolism of Imipramine can be increased when combined with Barbital. | Approved |
| Indalpine | The risk or severity of adverse effects can be increased when Barbital is combined with Indalpine. | Investigational, Withdrawn |
| Indapamide | Barbital may increase the orthostatic hypotensive activities of Indapamide. | Approved |
| Indenolol | The serum concentration of Indenolol can be decreased when it is combined with Barbital. | Withdrawn |
| Indoramin | Barbital may increase the hypotensive activities of Indoramin. | Withdrawn |
| Irbesartan | Barbital may increase the hypotensive activities of Irbesartan. | Approved, Investigational |
| Isocarboxazid | Barbital may increase the hypotensive activities of Isocarboxazid. | Approved |
| Isoflurane | The risk or severity of adverse effects can be increased when Isoflurane is combined with Barbital. | Approved, Vet Approved |
| Isosorbide Dinitrate | Barbital may increase the hypotensive activities of Isosorbide Dinitrate. | Approved |
| Isosorbide Mononitrate | Barbital may increase the hypotensive activities of Isosorbide Mononitrate. | Approved |
| Isoxsuprine | Barbital may increase the hypotensive activities of Isoxsuprine. | Approved, Withdrawn |
| Isradipine | Barbital may increase the hypotensive activities of Isradipine. | Approved |
| Ketamine | The risk or severity of adverse effects can be increased when Ketamine is combined with Barbital. | Approved, Vet Approved |
| Ketazolam | The risk or severity of adverse effects can be increased when Barbital is combined with Ketazolam. | Approved |
| Ketobemidone | The risk or severity of adverse effects can be increased when Barbital is combined with Ketobemidone. | Approved |
| Labetalol | Barbital may increase the hypotensive activities of Labetalol. | Approved |
| Lacidipine | The metabolism of Lacidipine can be increased when combined with Barbital. | Approved |
| Lamotrigine | The serum concentration of Lamotrigine can be decreased when it is combined with Barbital. | Approved, Investigational |
| Landiolol | The serum concentration of Aop200704 can be decreased when it is combined with Barbital. | Investigational |
| Lercanidipine | The metabolism of Lercanidipine can be increased when combined with Barbital. | Approved, Investigational |
| Levetiracetam | The risk or severity of adverse effects can be increased when Barbital is combined with Levetiracetam. | Approved, Investigational |
| Levobunolol | Barbital may increase the hypotensive activities of Levobunolol. | Approved |
| Levobupivacaine | The risk or severity of adverse effects can be increased when Levobupivacaine is combined with Barbital. | Approved |
| Levocabastine | The risk or severity of adverse effects can be increased when Barbital is combined with Levocabastine. | Approved |
| Levocetirizine | The risk or severity of adverse effects can be increased when Barbital is combined with Levocetirizine. | Approved |
| Levodopa | The risk or severity of adverse effects can be increased when Barbital is combined with Levodopa. | Approved |
| Levomethadyl Acetate | The risk or severity of adverse effects can be increased when Levomethadyl Acetate is combined with Barbital. | Approved |
| Levomilnacipran | The risk or severity of adverse effects can be increased when Barbital is combined with Levomilnacipran. | Approved |
| Levonorgestrel | The therapeutic efficacy of Levonorgestrel can be decreased when used in combination with Barbital. | Approved, Investigational |
| Levorphanol | The risk or severity of adverse effects can be increased when Levorphanol is combined with Barbital. | Approved |
| Levosimendan | Barbital may increase the hypotensive activities of Levosimendan. | Approved, Investigational |
| Lidocaine | The risk or severity of adverse effects can be increased when Lidocaine is combined with Barbital. | Approved, Vet Approved |
| Lisinopril | Barbital may increase the hypotensive activities of Lisinopril. | Approved, Investigational |
| Lithium | The risk or severity of adverse effects can be increased when Lithium is combined with Barbital. | Approved |
| Lofentanil | The risk or severity of adverse effects can be increased when Barbital is combined with Lofentanil. | Illicit |
| Lofexidine | Barbital may increase the hypotensive activities of Lofexidine. | Approved, Investigational |
| Loratadine | The risk or severity of adverse effects can be increased when Barbital is combined with Loratadine. | Approved |
| Lorazepam | The risk or severity of adverse effects can be increased when Lorazepam is combined with Barbital. | Approved |
| Losartan | Barbital may increase the hypotensive activities of Losartan. | Approved |
| Loxapine | The risk or severity of adverse effects can be increased when Loxapine is combined with Barbital. | Approved |
| Lurasidone | The risk or severity of adverse effects can be increased when Barbital is combined with Lurasidone. | Approved |
| Lynestrenol | The therapeutic efficacy of Lynestrenol can be decreased when used in combination with Barbital. | Investigational |
| Magnesium Sulfate | Magnesium Sulfate may increase the central nervous system depressant (CNS depressant) activities of Barbital. | Approved, Vet Approved |
| Manidipine | The metabolism of Manidipine can be increased when combined with Barbital. | Approved |
| Mannitol | Barbital may increase the hypotensive activities of Mannitol. | Approved, Investigational |
| Maprotiline | The risk or severity of adverse effects can be increased when Barbital is combined with Maprotiline. | Approved |
| Mecamylamine | Barbital may increase the hypotensive activities of Mecamylamine. | Approved |
| Meclizine | The risk or severity of adverse effects can be increased when Barbital is combined with Meclizine. | Approved |
| Medroxyprogesterone acetate | The therapeutic efficacy of Medroxyprogesterone acetate can be decreased when used in combination with Barbital. | Approved, Investigational |
| Melatonin | The risk or severity of adverse effects can be increased when Melatonin is combined with Barbital. | Approved, Nutraceutical, Vet Approved |
| Melperone | The risk or severity of adverse effects can be increased when Barbital is combined with Melperone. | Approved |
| Mepivacaine | The risk or severity of adverse effects can be increased when Mepivacaine is combined with Barbital. | Approved, Vet Approved |
| Meprobamate | The risk or severity of adverse effects can be increased when Meprobamate is combined with Barbital. | Approved, Illicit |
| Mesoridazine | The risk or severity of adverse effects can be increased when Mesoridazine is combined with Barbital. | Approved |
| Mestranol | The therapeutic efficacy of Mestranol can be decreased when used in combination with Barbital. | Approved |
| Metaxalone | The risk or severity of adverse effects can be increased when Barbital is combined with Metaxalone. | Approved |
| Methadone | The risk or severity of adverse effects can be increased when Methadone is combined with Barbital. | Approved |
| Methadyl Acetate | The risk or severity of adverse effects can be increased when Methadyl Acetate is combined with Barbital. | Approved, Illicit |
| Methallenestril | The therapeutic efficacy of Methallenestril can be decreased when used in combination with Barbital. | Experimental |
| Methapyrilene | The risk or severity of adverse effects can be increased when Barbital is combined with Methapyrilene. | Withdrawn |
| Methaqualone | The risk or severity of adverse effects can be increased when Barbital is combined with Methaqualone. | Illicit, Withdrawn |
| Methazolamide | Barbital may increase the hypotensive activities of Methazolamide. | Approved |
| Methocarbamol | The risk or severity of adverse effects can be increased when Barbital is combined with Methocarbamol. | Approved, Vet Approved |
| Methohexital | The risk or severity of adverse effects can be increased when Methohexital is combined with Barbital. | Approved |
| Methotrimeprazine | Barbital may increase the central nervous system depressant (CNS depressant) activities of Methotrimeprazine. | Approved |
| Methoxyflurane | The risk or severity of adverse effects can be increased when Methoxyflurane is combined with Barbital. | Approved, Vet Approved |
| Methsuximide | The risk or severity of adverse effects can be increased when Barbital is combined with Methsuximide. | Approved |
| Methyclothiazide | Barbital may increase the orthostatic hypotensive activities of Methyclothiazide. | Approved |
| Methyldopa | Barbital may increase the hypotensive activities of Methyldopa. | Approved |
| Methylecgonine | The risk or severity of adverse effects can be increased when Barbital is combined with ECGONINE METHYL ESTER. | Experimental |
| Methylphenobarbital | The risk or severity of adverse effects can be increased when Methylphenobarbital is combined with Barbital. | Approved |
| Metipranolol | Barbital may increase the hypotensive activities of Metipranolol. | Approved |
| Metolazone | Barbital may increase the orthostatic hypotensive activities of Metolazone. | Approved |
| Metoprolol | Barbital may increase the hypotensive activities of Metoprolol. | Approved, Investigational |
| Metyrosine | Barbital may increase the sedative activities of Metyrosine. | Approved |
| Mianserin | Mianserin may increase the central nervous system depressant (CNS depressant) activities of Barbital. | Approved |
| Mibefradil | The metabolism of Mibefradil can be increased when combined with Barbital. | Withdrawn |
| Midazolam | The risk or severity of adverse effects can be increased when Midazolam is combined with Barbital. | Approved, Illicit |
| Milnacipran | The risk or severity of adverse effects can be increased when Barbital is combined with Milnacipran. | Approved |
| Minocycline | Minocycline may increase the central nervous system depressant (CNS depressant) activities of Barbital. | Approved, Investigational |
| Minoxidil | Barbital may increase the hypotensive activities of Minoxidil. | Approved |
| Mirtazapine | Barbital may increase the central nervous system depressant (CNS depressant) activities of Mirtazapine. | Approved |
| Moexipril | Barbital may increase the hypotensive activities of Moexipril. | Approved |
| Molindone | The risk or severity of adverse effects can be increased when Barbital is combined with Molindone. | Approved |
| Morphine | The risk or severity of adverse effects can be increased when Morphine is combined with Barbital. | Approved, Investigational |
| Moxonidine | Barbital may increase the hypotensive activities of Moxonidine. | Approved |
| Nabilone | Nabilone may increase the central nervous system depressant (CNS depressant) activities of Barbital. | Approved, Investigational |
| Nadolol | Barbital may increase the hypotensive activities of Nadolol. | Approved |
| Naftopidil | The metabolism of Naftopidil can be increased when combined with Barbital. | Investigational |
| Nalbuphine | The risk or severity of adverse effects can be increased when Nalbuphine is combined with Barbital. | Approved |
| Nebivolol | Barbital may increase the hypotensive activities of Nebivolol. | Approved, Investigational |
| Nefazodone | The risk or severity of adverse effects can be increased when Barbital is combined with Nefazodone. | Approved, Withdrawn |
| Nesiritide | Barbital may increase the hypotensive activities of Nesiritide. | Approved, Investigational |
| Nicardipine | Barbital may increase the hypotensive activities of Nicardipine. | Approved |
| Nifedipine | Barbital may increase the hypotensive activities of Nifedipine. | Approved |
| Niguldipine | The metabolism of Niguldipine can be increased when combined with Barbital. | Experimental |
| Niludipine | The metabolism of Niludipine can be increased when combined with Barbital. | Experimental |
| Nilvadipine | The metabolism of Nilvadipine can be increased when combined with Barbital. | Approved |
| Nimesulide | The metabolism of Nimesulide can be increased when combined with Barbital. | Approved, Withdrawn |
| Nimodipine | Barbital may increase the hypotensive activities of Nimodipine. | Approved |
| Nisoldipine | Barbital may increase the hypotensive activities of Nisoldipine. | Approved |
| Nitrazepam | The risk or severity of adverse effects can be increased when Barbital is combined with Nitrazepam. | Approved |
| Nitrendipine | The metabolism of Nitrendipine can be increased when combined with Barbital. | Approved |
| Nitric Oxide | Barbital may increase the hypotensive activities of Nitric Oxide. | Approved |
| Nitroglycerin | Barbital may increase the hypotensive activities of Nitroglycerin. | Approved, Investigational |
| Nitroprusside | Barbital may increase the hypotensive activities of Nitroprusside. | Approved |
| Nitrous oxide | The risk or severity of adverse effects can be increased when Barbital is combined with Nitrous oxide. | Approved, Vet Approved |
| Norelgestromin | The therapeutic efficacy of Norelgestromin can be decreased when used in combination with Barbital. | Approved |
| Norflurane | The risk or severity of adverse effects can be increased when Barbital is combined with 1,1,1,2 Tetrafluoroethane. | Investigational |
| Norgestimate | The therapeutic efficacy of Norgestimate can be decreased when used in combination with Barbital. | Approved |
| Norgestrel | The therapeutic efficacy of Norgestrel can be decreased when used in combination with Barbital. | Approved |
| Normethadone | The risk or severity of adverse effects can be increased when Barbital is combined with Normethadone. | Approved, Illicit |
| Nortriptyline | The metabolism of Nortriptyline can be increased when combined with Barbital. | Approved |
| Obinutuzumab | Barbital may increase the hypotensive activities of Obinutuzumab. | Approved |
| Olanzapine | The risk or severity of adverse effects can be increased when Olanzapine is combined with Barbital. | Approved, Investigational |
| Olmesartan | Barbital may increase the hypotensive activities of Olmesartan. | Approved, Investigational |
| Olopatadine | The risk or severity of adverse effects can be increased when Barbital is combined with Olopatadine. | Approved |
| Ondansetron | The risk or severity of adverse effects can be increased when Ondansetron is combined with Barbital. | Approved |
| Opipramol | The metabolism of Opipramol can be increased when combined with Barbital. | Investigational |
| Opium | The risk or severity of adverse effects can be increased when Barbital is combined with Opium. | Approved, Illicit |
| Orphenadrine | Barbital may increase the central nervous system depressant (CNS depressant) activities of Orphenadrine. | Approved |
| Osanetant | The risk or severity of adverse effects can be increased when Barbital is combined with Osanetant. | Investigational |
| Oxazepam | The risk or severity of adverse effects can be increased when Oxazepam is combined with Barbital. | Approved |
| Oxethazaine | The risk or severity of adverse effects can be increased when Barbital is combined with Oxetacaine. | Investigational |
| Oxprenolol | The risk or severity of adverse effects can be increased when Barbital is combined with Oxprenolol. | Approved |
| Oxybuprocaine | The risk or severity of adverse effects can be increased when Oxybuprocaine is combined with Barbital. | Approved |
| Oxycodone | The risk or severity of adverse effects can be increased when Oxycodone is combined with Barbital. | Approved, Illicit, Investigational |
| Oxymorphone | The risk or severity of adverse effects can be increased when Oxymorphone is combined with Barbital. | Approved, Investigational, Vet Approved |
| Paclitaxel | Barbital may increase the hypotensive activities of Paclitaxel. | Approved, Vet Approved |
| Paliperidone | The risk or severity of adverse effects can be increased when Paliperidone is combined with Barbital. | Approved |
| Papaverine | Barbital may increase the hypotensive activities of Papaverine. | Approved |
| Paraldehyde | Barbital may increase the central nervous system depressant (CNS depressant) activities of Paraldehyde. | Approved |
| Paroxetine | The risk or severity of adverse effects can be increased when Barbital is combined with Paroxetine. | Approved, Investigational |
| Penbutolol | Barbital may increase the hypotensive activities of Penbutolol. | Approved, Investigational |
| Pentazocine | The risk or severity of adverse effects can be increased when Pentazocine is combined with Barbital. | Approved, Vet Approved |
| Pentobarbital | The risk or severity of adverse effects can be increased when Pentobarbital is combined with Barbital. | Approved, Vet Approved |
| Perampanel | Perampanel may increase the central nervous system depressant (CNS depressant) activities of Barbital. | Approved |
| Perazine | The risk or severity of adverse effects can be increased when Barbital is combined with Perazine. | Investigational |
| Perhexiline | The metabolism of Perhexiline can be increased when combined with Barbital. | Approved |
| Perindopril | Barbital may increase the hypotensive activities of Perindopril. | Approved |
| Perospirone | The risk or severity of adverse effects can be increased when Barbital is combined with Perospirone. | Approved |
| Perphenazine | The risk or severity of adverse effects can be increased when Perphenazine is combined with Barbital. | Approved |
| Pethidine | Barbital may increase the central nervous system depressant (CNS depressant) activities of Pethidine. | Approved |
| Phenelzine | Barbital may increase the hypotensive activities of Phenelzine. | Approved |
| Phenindione | The metabolism of Phenindione can be increased when combined with Barbital. | Approved |
| Phenobarbital | The risk or severity of adverse effects can be increased when Phenobarbital is combined with Barbital. | Approved |
| Phenoxybenzamine | Barbital may increase the hypotensive activities of Phenoxybenzamine. | Approved |
| Phenprocoumon | The metabolism of Phenprocoumon can be increased when combined with Barbital. | Approved |
| Phentolamine | Barbital may increase the hypotensive activities of Phentolamine. | Approved |
| Phenytoin | The risk or severity of adverse effects can be increased when Barbital is combined with Phenytoin. | Approved, Vet Approved |
| Pimozide | The risk or severity of adverse effects can be increased when Pimozide is combined with Barbital. | Approved |
| Pinaverium | The metabolism of Pinaverium can be increased when combined with Barbital. | Approved |
| Pindolol | Barbital may increase the hypotensive activities of Pindolol. | Approved |
| Pipamperone | The risk or severity of adverse effects can be increased when Barbital is combined with Pipamperone. | Approved |
| Pipotiazine | The risk or severity of adverse effects can be increased when Barbital is combined with Pipotiazine. | Approved |
| Piritramide | The risk or severity of adverse effects can be increased when Barbital is combined with Piritramide. | Investigational |
| Polythiazide | Barbital may increase the orthostatic hypotensive activities of Polythiazide. | Approved |
| Pomalidomide | The risk or severity of adverse effects can be increased when Barbital is combined with Pomalidomide. | Approved |
| Practolol | The serum concentration of Practolol can be decreased when it is combined with Barbital. | Approved |
| Pramipexole | Barbital may increase the sedative activities of Pramipexole. | Approved, Investigational |
| Pramocaine | The risk or severity of adverse effects can be increased when Barbital is combined with Pramocaine. | Approved |
| Prazepam | The risk or severity of adverse effects can be increased when Barbital is combined with Prazepam. | Approved, Illicit |
| Prazosin | Barbital may increase the hypotensive activities of Prazosin. | Approved |
| Pregabalin | The risk or severity of adverse effects can be increased when Pregabalin is combined with Barbital. | Approved, Illicit, Investigational |
| Prenylamine | The metabolism of Prenylamine can be increased when combined with Barbital. | Withdrawn |
| Prilocaine | The risk or severity of adverse effects can be increased when Prilocaine is combined with Barbital. | Approved |
| Primidone | The risk or severity of adverse effects can be increased when Primidone is combined with Barbital. | Approved, Vet Approved |
| Procaine | The risk or severity of adverse effects can be increased when Procaine is combined with Barbital. | Approved, Investigational, Vet Approved |
| Prochlorperazine | The risk or severity of adverse effects can be increased when Prochlorperazine is combined with Barbital. | Approved, Vet Approved |
| Promazine | The risk or severity of adverse effects can be increased when Promazine is combined with Barbital. | Approved, Vet Approved |
| Promethazine | The risk or severity of adverse effects can be increased when Barbital is combined with Promethazine. | Approved |
| Propacetamol | The metabolism of Propacetamol can be increased when combined with Barbital. | Approved |
| Proparacaine | The risk or severity of adverse effects can be increased when Proparacaine is combined with Barbital. | Approved, Vet Approved |
| Propofol | The risk or severity of adverse effects can be increased when Propofol is combined with Barbital. | Approved, Investigational, Vet Approved |
| Propoxycaine | The risk or severity of adverse effects can be increased when Barbital is combined with Propoxycaine. | Approved |
| Propranolol | Barbital may increase the hypotensive activities of Propranolol. | Approved, Investigational |
| Protriptyline | The metabolism of Protriptyline can be increased when combined with Barbital. | Approved |
| Pyridoxine | The metabolism of Barbital can be increased when combined with Pyridoxine. | Approved, Nutraceutical, Vet Approved |
| Quazepam | The risk or severity of adverse effects can be increased when Barbital is combined with Quazepam. | Approved, Illicit |
| Quetiapine | The risk or severity of adverse effects can be increased when Quetiapine is combined with Barbital. | Approved |
| Quinapril | Barbital may increase the hypotensive activities of Quinapril. | Approved, Investigational |
| Quinethazone | Barbital may increase the orthostatic hypotensive activities of Quinethazone. | Approved |
| Raclopride | The risk or severity of adverse effects can be increased when Barbital is combined with Raclopride. | Investigational |
| Ramelteon | The risk or severity of adverse effects can be increased when Barbital is combined with Ramelteon. | Approved, Investigational |
| Ramipril | Barbital may increase the hypotensive activities of Ramipril. | Approved |
| Rasagiline | Barbital may increase the hypotensive activities of Rasagiline. | Approved |
| Remifentanil | The risk or severity of adverse effects can be increased when Remifentanil is combined with Barbital. | Approved |
| Remoxipride | The risk or severity of adverse effects can be increased when Remoxipride is combined with Barbital. | Approved, Withdrawn |
| Reserpine | The risk or severity of adverse effects can be increased when Reserpine is combined with Barbital. | Approved |
| Rifabutin | The metabolism of Barbital can be increased when combined with Rifabutin. | Approved |
| Rifampicin | The metabolism of Barbital can be increased when combined with Rifampicin. | Approved |
| Rifapentine | The metabolism of Barbital can be increased when combined with Rifapentine. | Approved |
| Riociguat | Barbital may increase the hypotensive activities of Riociguat. | Approved |
| Risedronate | The metabolism of Risedronate can be increased when combined with Barbital. | Approved, Investigational |
| Risperidone | The risk or severity of adverse effects can be increased when Risperidone is combined with Barbital. | Approved, Investigational |
| Ritanserin | The risk or severity of adverse effects can be increased when Barbital is combined with Ritanserin. | Investigational |
| Ropinirole | Barbital may increase the sedative activities of Ropinirole. | Approved, Investigational |
| Ropivacaine | The risk or severity of adverse effects can be increased when Ropivacaine is combined with Barbital. | Approved |
| Rotigotine | Barbital may increase the sedative activities of Rotigotine. | Approved |
| Rufinamide | The risk or severity of adverse effects can be increased when Rufinamide is combined with Barbital. | Approved |
| Sacubitril | Barbital may increase the hypotensive activities of Sacubitril. | Approved |
| Scopolamine | The risk or severity of adverse effects can be increased when Barbital is combined with Scopolamine. | Approved |
| Secobarbital | The risk or severity of adverse effects can be increased when Secobarbital is combined with Barbital. | Approved, Vet Approved |
| Selegiline | Barbital may increase the hypotensive activities of Selegiline. | Approved, Investigational, Vet Approved |
| Sepranolone | The risk or severity of adverse effects can be increased when Barbital is combined with Uc1010. | Investigational |
| Sertindole | The risk or severity of adverse effects can be increased when Barbital is combined with Sertindole. | Approved, Withdrawn |
| Sertraline | The risk or severity of adverse effects can be increased when Barbital is combined with Sertraline. | Approved |
| Sevoflurane | The risk or severity of adverse effects can be increased when Sevoflurane is combined with Barbital. | Approved, Vet Approved |
| Sodium Nitrite | Barbital may increase the hypotensive activities of Sodium Nitrite. | Approved |
| Sodium oxybate | Sodium oxybate may increase the central nervous system depressant (CNS depressant) activities of Barbital. | Approved |
| Somatostatin | The risk or severity of adverse effects can be increased when Somatostatin is combined with Barbital. | Approved |
| Sotalol | Barbital may increase the hypotensive activities of Sotalol. | Approved |
| Spironolactone | Barbital may increase the hypotensive activities of Spironolactone. | Approved |
| Stiripentol | The risk or severity of adverse effects can be increased when Barbital is combined with Stiripentol. | Approved |
| Streptokinase | Barbital may increase the hypotensive activities of Streptokinase. | Approved |
| Sufentanil | The risk or severity of adverse effects can be increased when Sufentanil is combined with Barbital. | Approved, Investigational |
| Sulpiride | The risk or severity of adverse effects can be increased when Sulpiride is combined with Barbital. | Approved |
| Suvorexant | Barbital may increase the central nervous system depressant (CNS depressant) activities of Suvorexant. | Approved |
| Synthetic Conjugated Estrogens, A | The therapeutic efficacy of Synthetic Conjugated Estrogens, A can be decreased when used in combination with Barbital. | Approved |
| Tamsulosin | Barbital may increase the hypotensive activities of Tamsulosin. | Approved, Investigational |
| Tandospirone | The risk or severity of adverse effects can be increased when Barbital is combined with Tandospirone. | Investigational |
| Tapentadol | Tapentadol may increase the central nervous system depressant (CNS depressant) activities of Barbital. | Approved |
| Tasimelteon | The risk or severity of adverse effects can be increased when Barbital is combined with Tasimelteon. | Approved |
| Telmisartan | Barbital may increase the hypotensive activities of Telmisartan. | Approved, Investigational |
| Temazepam | The risk or severity of adverse effects can be increased when Temazepam is combined with Barbital. | Approved |
| Teniposide | The serum concentration of Teniposide can be decreased when it is combined with Barbital. | Approved |
| Terazosin | Barbital may increase the hypotensive activities of Terazosin. | Approved |
| Tetrabenazine | The risk or severity of adverse effects can be increased when Barbital is combined with Tetrabenazine. | Approved |
| Tetracaine | The risk or severity of adverse effects can be increased when Barbital is combined with Tetracaine. | Approved, Vet Approved |
| Tetrodotoxin | The risk or severity of adverse effects can be increased when Barbital is combined with Tetrodotoxin. | Investigational |
| Thalidomide | Barbital may increase the central nervous system depressant (CNS depressant) activities of Thalidomide. | Approved, Investigational, Withdrawn |
| Theophylline | The serum concentration of Theophylline can be decreased when it is combined with Barbital. | Approved |
| Thiamylal | The risk or severity of adverse effects can be increased when Thiamylal is combined with Barbital. | Approved, Vet Approved |
| Thiopental | The risk or severity of adverse effects can be increased when Thiopental is combined with Barbital. | Approved, Vet Approved |
| Thioridazine | The risk or severity of adverse effects can be increased when Thioridazine is combined with Barbital. | Withdrawn |
| Thiothixene | The risk or severity of adverse effects can be increased when Barbital is combined with Thiothixene. | Approved |
| Tiagabine | The risk or severity of adverse effects can be increased when Barbital is combined with Tiagabine. | Approved |
| Tianeptine | The metabolism of Tianeptine can be increased when combined with Barbital. | Approved |
| Tiapride | The risk or severity of adverse effects can be increased when Barbital is combined with Tiapride. | Approved, Investigational |
| Timolol | Barbital may increase the hypotensive activities of Timolol. | Approved |
| Tizanidine | The risk or severity of adverse effects can be increased when Barbital is combined with Tizanidine. | Approved |
| Tolazoline | Barbital may increase the hypotensive activities of Tolazoline. | Approved, Vet Approved |
| Tolcapone | The risk or severity of adverse effects can be increased when Barbital is combined with Tolcapone. | Approved, Withdrawn |
| Tolfenamic Acid | The metabolism of Tolfenamic Acid can be increased when combined with Barbital. | Approved |
| Topiramate | The risk or severity of adverse effects can be increased when Barbital is combined with Topiramate. | Approved |
| Torasemide | Barbital may increase the hypotensive activities of Torasemide. | Approved |
| Tramadol | The risk or severity of adverse effects can be increased when Tramadol is combined with Barbital. | Approved, Investigational |
| Trandolapril | Barbital may increase the hypotensive activities of Trandolapril. | Approved |
| Tranilast | The metabolism of Tranilast can be increased when combined with Barbital. | Approved, Investigational |
| Trans-2-Phenylcyclopropylamine | The risk or severity of adverse effects can be increased when Barbital is combined with Trans-2-Phenylcyclopropylamine. | Experimental |
| Tranylcypromine | The risk or severity of adverse effects can be increased when Tranylcypromine is combined with Barbital. | Approved |
| Trazodone | The risk or severity of adverse effects can be increased when Trazodone is combined with Barbital. | Approved, Investigational |
| Tretinoin | Barbital may increase the hypotensive activities of Tretinoin. | Approved, Investigational, Nutraceutical |
| Triamterene | Barbital may increase the hypotensive activities of Triamterene. | Approved |
| Triazolam | The risk or severity of adverse effects can be increased when Triazolam is combined with Barbital. | Approved |
| Trichlormethiazide | Barbital may increase the orthostatic hypotensive activities of Trichlormethiazide. | Approved, Vet Approved |
| Trifluoperazine | The risk or severity of adverse effects can be increased when Trifluoperazine is combined with Barbital. | Approved |
| Triflupromazine | The risk or severity of adverse effects can be increased when Triflupromazine is combined with Barbital. | Approved, Vet Approved |
| Trimipramine | The metabolism of Trimipramine can be increased when combined with Barbital. | Approved |
| Triprolidine | The risk or severity of adverse effects can be increased when Barbital is combined with Triprolidine. | Approved |
| Ulipristal | The serum concentration of Ulipristal can be decreased when it is combined with Barbital. | Approved |
| Valproic Acid | The serum concentration of Barbital can be increased when it is combined with Valproic Acid. | Approved, Investigational |
| Valsartan | Barbital may increase the hypotensive activities of Valsartan. | Approved, Investigational |
| Venlafaxine | The risk or severity of adverse effects can be increased when Barbital is combined with Venlafaxine. | Approved |
| Verapamil | Barbital may increase the hypotensive activities of Verapamil. | Approved |
| Vigabatrin | The risk or severity of adverse effects can be increased when Barbital is combined with Vigabatrin. | Approved |
| Vinpocetine | The metabolism of Vinpocetine can be increased when combined with Barbital. | Investigational |
| Voriconazole | The serum concentration of Voriconazole can be decreased when it is combined with Barbital. | Approved, Investigational |
| Vortioxetine | The risk or severity of adverse effects can be increased when Barbital is combined with Vortioxetine. | Approved |
| Warfarin | The metabolism of Warfarin can be increased when combined with Barbital. | Approved |
| Xylometazoline | The metabolism of Xylometazoline can be increased when combined with Barbital. | Approved |
| Zaleplon | The risk or severity of adverse effects can be increased when Zaleplon is combined with Barbital. | Approved, Illicit, Investigational |
| Ziconotide | The risk or severity of adverse effects can be increased when Barbital is combined with Ziconotide. | Approved |
| Zimelidine | The risk or severity of adverse effects can be increased when Barbital is combined with Zimelidine. | Withdrawn |
| Ziprasidone | The risk or severity of adverse effects can be increased when Ziprasidone is combined with Barbital. | Approved |
| Zolpidem | Barbital may increase the central nervous system depressant (CNS depressant) activities of Zolpidem. | Approved |
| Zonisamide | The risk or severity of adverse effects can be increased when Barbital is combined with Zonisamide. | Approved, Investigational |
| Zopiclone | The risk or severity of adverse effects can be increased when Zopiclone is combined with Barbital. | Approved |
| Zotepine | The risk or severity of adverse effects can be increased when Barbital is combined with Zotepine. | Approved |
| Zuclopenthixol | The risk or severity of adverse effects can be increased when Barbital is combined with Zuclopenthixol. | Approved, Investigational |
