Potassium hydroxide


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Potassium hydroxide
Accession Number
Small Molecule

Potassium hydroxide, also known as lye is an inorganic compound with the chemical formula KOH. Also commonly referred to as caustic potash, it is a potent base that is marketed in several forms including pellets, flakes, and powders. It is used in various chemical, industrial and manufacturing applications. Potassium hydroxide is also a precursor to other potassium compounds. Potassium hydroxide is used in food to adjust pH, as a stabilizer, and as a thickening agent.6,10 This ingredient has been considered as generally safe as a direct human food ingredient by the FDA, based upon the observance of several good manufacturing practice conditions of use.4

In addition to the above uses, potassium hydroxide is also used in making soap, as an electrolyte in alkaline batteries and in electroplating, lithography, and paint and varnish removers. Liquid drain cleaners contain 25 to 36% of potassium hydroxide 6.

Medically, potassium hydroxide (KOH) is widely used in the wet mount preparation of various clinical specimens for microscopic visualization of fungi and fungal elements in skin, hair, nails, and even vaginal secretions 1, 6.

Recently, it has been studied for efficacy and tolerability in the treatment of warts. It was determined that topical KOH solution was found to be a safe and effective treatment of plane warts 2.

  • Ätzkali
  • hydroxyde de potassium
  • Kaliumhydroxid
  • potash lye
  • potasio hidróxido
  • potasse caustique
External IDs
E-525 / INS NO.525 / INS-525
Active Moieties
Potassium cationionic295O53K15224203-36-9NPYPAHLBTDXSSS-UHFFFAOYSA-N
Hydroxide ionionic9159UV381P14280-30-9XLYOFNOQVPJJNP-UHFFFAOYSA-M
Prescription Products
NameDosageStrengthRouteLabellerMarketing StartMarketing End
Potassium HydroxideLiquid.05 g/1gTopicalGordon Laboratories2010-07-16Not applicableUs
Additional Data Available
  • Application Number
    Application Number

    A unique ID assigned by the FDA when a product is submitted for approval by the labeller.

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  • Product Code
    Product Code

    A governmentally-recognized ID which uniquely identifies the product within its regulatory market.

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Over the Counter Products
NameDosageStrengthRouteLabellerMarketing StartMarketing End
OHTrust Nano Ion WaterLiquid0.2 g/100mLTopicalNanoplus Limited (Cayman) Taiwan Branch2016-09-26Not applicableUs
Additional Data Available
  • Application Number
    Application Number

    A unique ID assigned by the FDA when a product is submitted for approval by the labeller.

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  • Product Code
    Product Code

    A governmentally-recognized ID which uniquely identifies the product within its regulatory market.

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Mixture Products
NameIngredientsDosageRouteLabellerMarketing StartMarketing End
Tincture GreenPotassium hydroxide (5.961 g/100mL) + Ethanol (24.93 g/100mL) + Rosin (2.47 g/100mL)LiquidTopicalMedical Chemical Corporation1954-06-15Not applicableUs
Tincture Green SoapPotassium hydroxide (5.961 g/100mL) + Ethanol (24.93 g/100mL) + Rosin (2.47 g/100mL)LiquidTopicalMedical Chemical Corporation1954-06-15Not applicableUs
Vamin NPotassium hydroxide (97 mg) + Alanine (300 mg) + Arginine (330 mg) + Aspartic acid (410 mg) + Calcium chloride (36.8 mg) + Cysteine (140 mg) + Glutamic acid (900 mg) + Glycine (210 mg) + Histidine (240 mg) + Isoleucine (390 mg) + L-Lysine (390 mg) + Leucine (530 mg) + Magnesium sulfate (37 mg) + Methionine (190 mg) + Phenylalanine (550 mg) + Potassium chloride (37.5 mg) + Proline (810 mg) + Serine (750 mg) + Sodium hydroxide (200 mg) + Threonine (300 mg) + Tryptophan (100 mg) + Tyrosine (50 mg) + Valine (425 mg)SolutionIntravenousFresenius Kabi Ab1995-12-312006-07-17Canada
Unapproved/Other Products
NameIngredientsDosageRouteLabellerMarketing StartMarketing End
OHTrust Nano Ion WaterPotassium hydroxide (0.2 g/100mL)LiquidTopicalNanoplus Limited (Cayman) Taiwan Branch2016-09-26Not applicableUs
Potassium HydroxidePotassium hydroxide (.05 g/1g)LiquidTopicalGordon Laboratories2010-07-16Not applicableUs
CAS number
Average: 56.1056
Monoisotopic: 55.966446515
Chemical Formula
InChI Key
potassium hydroxide



Medically, the microscopic examination of potassium hydroxide (KOH) preparations is utilized in the diagnosis of fungal hyphae or trichomonads 9.

Samples from hair, skin, or nail tissue are obtained by scraping with a scalpel, cotton-tipped applicator and are inoculated directly onto the KOH solution 9.

In addition to the above, potassium hydroxide is used as a softener for nail grooves 8.


The corrosiveness of potassium hydroxide renders it a very useful agent in the decomposition/removal soft tissue and hair removal. It is incorporated into some nail products, shaving creams, and soaps 13.

Mechanism of action

The exact mechanism of action of KOH is not known but the speculated one is that topical application of KOH digests keratin, and induces inflammation 7.

The mechanism of skin injury by alkali substances such as potassium hydroxide is by the saponification of fat, causing fatty tissue to lose its function with increased damage due to a heat reaction. Extraction of water from cells occurs due to the hygroscopic (absorbent) nature of alkali. Dissolution of proteins also occurs, allowing for deeper penetration of OH- ions and resulting in various chemical reactions 14.

The alkali penetrates the skin quickly, saponifies plasma membranes, denatures collagen proteins, and leads to vascular thromboses in the conjunctiva and other parts of the eye. The resulting corneal burns include scarring and opacification of the cornea with resulting in vision loss, corneal neovascularization, ulcer formation, and perforation. Other consequences of untreated or very severe alkali burns include epithelial erosions, secondary glaucoma, and causes the destruction of conjunctival mucus cells, causing dry eyes, trichiasis (misdirected eyelash hairs), and other ocular conditions 14.

In the gastrointestinal tract, after oral ingestion, burns may result. The mechanism of injury is liquefactive necrosis. The thrombosis of gastrointestinal blood vessels also contributes to tissue damage. When the alkali enters the stomach, gastric acid may neutralize the strong base, which can limit the extent of the injury. Perforation of the stomach can sometimes occur with peritonitis and caustic injury to the surrounding organs including the colon, pancreas, liver, and spleen 14.

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KOH in aqueous solutions completely dissociates into K+ and OH- ions. Because of the neutralization of OH- by gastric HCl and the rapid blood pH regulation action (buffer capacity of extracellular body fluids, respiratory and renal compensation mechanisms), an alkalosis due to the OH- ions after KOH oral dosage in non-irritating conditions is thus prevented 3.

The uptake of potassium, in potassium hydroxide form, is much less than the oral uptake with therapeutic doses of KCl for treating potassium deficiency, of up to 10 g/day. Furthermore, the oral uptake of potassium from food/natural sources or from food additives is likely to be also much higher 3.

Volume of distribution
Not Available
Protein binding
Not Available

KOH in aqueous solution is entirely dissociated into K+ and OH- ions. Due to the neutralization of OH- by gastric HCl and the quick and efficient blood pH regulation mechanisms (buffer capacity of extra cellular body fluids, respiratory and renal compensation mechanisms), an alkalosis due to the OH- ions after KOH oral dosage in non-irritating conditions is prevented 14.

Route of elimination
Not Available
Half life
Not Available
Not Available

No studies are currently identified regarding the reproduction/developmental toxicity of potassium hydroxide 14.

The Ld50 of potassium hydroxide in rats ranges from 0.273 - 1.230 g KOH/kg body weight/day 3.

Adverse effects include vomiting, diarrhea, skin blistering, gastrointestinal disturbance, and burns 5.

Strong alkaline chemicals such as potassium hydroxide destroy soft tissues may cause a deep, penetrating type of burn. Caustics are usually hydroxides of light metals. Sodium hydroxide and potassium hydroxide are the most broadly used caustic agents in the industry 11.

Potassium Hydroxide can irritate the lungs. Repeated exposure may cause bronchitis to develop with coughing, phlegm, and/or shortness of breath 9.

Affected organisms
Not Available
Not Available
Pharmacogenomic Effects/ADRs
Not Available


Drug Interactions
This information should not be interpreted without the help of a healthcare provider. If you believe you are experiencing an interaction, contact a healthcare provider immediately. The absence of an interaction does not necessarily mean no interactions exist.
AcebutololPotassium hydroxide may increase the hyperkalemic activities of Acebutolol.
AceclofenacPotassium hydroxide may increase the hyperkalemic activities of Aceclofenac.
AcemetacinPotassium hydroxide may increase the hyperkalemic activities of Acemetacin.
Acetylsalicylic acidPotassium hydroxide may increase the hyperkalemic activities of Acetylsalicylic acid.
AgmatinePotassium hydroxide may increase the hyperkalemic activities of Agmatine.
AlclofenacPotassium hydroxide may increase the hyperkalemic activities of Alclofenac.
AliskirenPotassium hydroxide may increase the hyperkalemic activities of Aliskiren.
AlminoprofenPotassium hydroxide may increase the hyperkalemic activities of Alminoprofen.
AlprenololPotassium hydroxide may increase the hyperkalemic activities of Alprenolol.
AmilorideThe risk or severity of hyperkalemia can be increased when Potassium hydroxide is combined with Amiloride.
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Food Interactions
Not Available


General References
  1. Parija SC, Shivaprakash MR: Evaluation of potassium hydroxide for wet mount preparation of stool for detection of intestinal parasites. Diagn Microbiol Infect Dis. 2001 Nov;41(3):127-30. [PubMed:11750165]
  2. Evaluation of Topical Potassium Hydroxide Solution for Treatment of Plane Warts [Link]
  3. Potassium Hydroxide [Link]
  4. FDA document, potassium hydroxide [Link]
  5. Potassium [Link]
  6. NJ Gov Document, Potassium Hydroxide [Link]
  7. Comparison of 5% potassium hydroxide with 10% potassium hydroxide solution in treatment of molluscum contagiosum: A comparative study [Link]
  8. Potassium Hydroxide Liquid [Link]
  9. Potassium hydroxide overview [Link]
  10. Overview of KOH [Link]
  11. NIH MeSH search, Potassium Hydroxide [Link]
  12. ECHA information page, Potassium Hydroxide [Link]
  13. Potassium Hydroxide- Continental Chemical [Link]
  14. InCHEM, Potassium Hydroxide [Link]
External Links
KEGG Compound
PubChem Compound
PubChem Substance
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Clinical Trials

Clinical Trials
Not Available


Not Available
Not Available
Dosage forms
LiquidTopical0.2 g/100mL
LiquidTopical.05 g/1g
Not Available
Not Available


Experimental Properties
melting point (°C)405MSDS
boiling point (°C)1,320MSDS
water solubilitySoluble MSDS
Predicted Properties
pKa (Strongest Acidic)3.09ChemAxon
Physiological Charge1ChemAxon
Hydrogen Acceptor Count0ChemAxon
Hydrogen Donor Count0ChemAxon
Polar Surface Area0 Å2ChemAxon
Rotatable Bond Count0ChemAxon
Refractivity0 m3·mol-1ChemAxon
Polarizability1.78 Å3ChemAxon
Number of Rings0ChemAxon
Rule of FiveYesChemAxon
Ghose FilterNoChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleNoChemAxon
Predicted ADMET features
Not Available


Mass Spec (NIST)
Not Available
Not Available


This compound belongs to the class of inorganic compounds known as alkali metal hydroxides. These are inorganic compounds in which the largest oxoanion is hydroxide, and in which the heaviest atom not in an oxoanion is an alkali metal.
Inorganic compounds
Super Class
Mixed metal/non-metal compounds
Alkali metal oxoanionic compounds
Sub Class
Alkali metal hydroxides
Direct Parent
Alkali metal hydroxides
Alternative Parents
Inorganic salts / Inorganic oxides / Inorganic hydrides
Alkali metal hydroxide / Inorganic hydride / Inorganic oxide / Inorganic salt
Molecular Framework
Not Available
External Descriptors
alkali metal hydroxide (CHEBI:32035)

Drug created on December 03, 2015 09:51 / Updated on December 02, 2019 08:58