POTASSIUM HYDROXIDE
Commonly Found In
Overview
Potassium hydroxide (KOH, caustic potash) is a strong alkali used as a pH adjuster and saponification agent in cosmetics. At high concentrations it is caustic and corrosive, but in finished cosmetic formulations it is used in very small amounts to achieve target pH, where it is neutralized and poses minimal risk. The EU restricts it under Annex III with pH limits.
Also known as: caustic potash, lye (potassium form), KOH, potassium hydrate
Key Benefits
No direct skin benefit at cosmetic-use levels; functions as a pH adjuster. At high concentrations, KOH is caustic and can cause chemical burns. In finished products neutralized to appropriate pH, studies suggest it poses minimal risk.
Supporting Research
- β’ CIR Expert Panel β Safety Assessment of KOH: Safe in cosmetics when formulated to final pH β€11
- β’ EU Annex III/15a, 15d: Restricts KOH with final product pH limits to protect consumer safety
Skin Compatibility Ratings
Comedogenic Rating
Non-comedogenic; inorganic base used only as a pH adjuster; not present in its corrosive form in finished products.
Source: CIR Expert Panel; physicochemical properties
Irritancy Rating
Score applies to concentrated KOH (3β4). At diluted use levels in finished formulations (pH-adjusted), irritancy is typically score 1. Caustic at high concentrations.
Source: CIR Expert Panel; EU Annex III
Typical Use Concentration
Range
0.01β1% as pH adjuster
Optimal
Quantity sufficient to achieve target pH
EU restricts by final product pH rather than KOH concentration per se. Not used at high concentrations in cosmetics; trace amounts remain after neutralization.
Works Well With / Avoid
Works Well With
Avoid Combining
Use With Caution
EU Annex III/15a, 15d restricts KOH with final product pH limits. Used only in small amounts to adjust pH; not present in excess in finished formulations. Caustic at high concentrations β handle with care in manufacturing.
Commonly Found In
Global Regulation Summary
Overview of current status across major international markets.
Detailed Regional Status
| Region | Status | Max Conc. | Conditions | Source |
|---|---|---|---|---|
| πͺπΊ EU | Banned | - | - | Official β |
| πΊπΈ USA | Allowed | - | - | Official β |
| π―π΅ Japan | Allowed | - | - | Official β |
| π°π· Korea | Unknown | - | - | Official β |
| π¬π§ UK | Restricted | - | Follows EU regulations (III/15a, 15d) | Official β |
π Why Regulations Differ
EU Annex III/15a, 15d restricts KOH use based on final product pH limits (different limits for different product categories). Japan and US permit use as a pH adjuster without specific KOH concentration limits, relying on general safety standards. The caustic risk at high concentrations drives the EU/UK regulatory approach.
Regulation Analysis
Regional Agreement
Banned in EU but allowed in USA, Japan.
Category Comparison
There are 41 ingredients in the BUFFERING category. 100% are banned in at least one major market.
Strictness Ranking
πΏ Natural Sources
Not found in nature in pure form. However, potash (potassium carbonate) was historically obtained from wood ash β the word 'potassium' itself comes from 'pot ash'.
π How It's Made
Produced by electrolysis of potassium chloride solution (similar to how sodium hydroxide is made from sodium chloride). Also made by reacting potassium with water.
π Uses in Cosmetics
Used as a pH adjuster in creams, lotions, and cleansers to achieve target formulation pH. Essential for soap-making via saponification of oils. EU Annex III restricts final product pH.
π¬ Other Applications
Used in liquid soap manufacturing, food processing (cocoa, olives), battery electrolyte, biodiesel production, and as a chemical reagent. Also used in alkaline batteries.
π‘ Fun Facts
- β’ Potassium hydroxide is used to make soft or liquid soaps, while sodium hydroxide makes hard bar soaps β this is why liquid soaps feel different
- β’ Potassium was the first metal to be isolated by electrolysis, by Humphry Davy in 1807
- β’ Traditional African black soap is made using potassium hydroxide from plantain ash rather than the sodium hydroxide used in Western soap-making
Data Sources
- β’ EU Cosmetics Regulation 1223/2009 Annex III entries 15a and 15d
- β’ CIR Expert Panel β Safety Assessment of Potassium Hydroxide
Last data verification: 2026-04-16
Related Ingredients
AMMONIA
AMMONIUM HYDROXIDE
DIETHANOLAMINE
SODIUM HYDROXIDE
TRIETHANOLAMINE
CALCIUM CARBONATE
Learn More
Frequently Asked Questions
Why is POTASSIUM HYDROXIDE banned in the EU but allowed in the US?
The EU follows a precautionary principle, banning POTASSIUM HYDROXIDE under III/15a, 15d due to potential safety concerns. The US FDA has not found sufficient evidence to prohibit its use, allowing it under different safety assessment standards. This reflects differing regulatory philosophies between the two regions.
Why is POTASSIUM HYDROXIDE banned in the EU but allowed in Japan?
The EU prohibits POTASSIUM HYDROXIDE (III/15a, 15d) based on their strict safety criteria. Japan's Ministry of Health, Labour and Welfare (MHLW) has evaluated the ingredient and permits its use, potentially with different safety data or usage conditions.
What is POTASSIUM HYDROXIDE used for in cosmetics?
POTASSIUM HYDROXIDE is primarily used for buffering in cosmetic products. The ingredient is commonly found in various cosmetic and personal care products.
Which countries regulate POTASSIUM HYDROXIDE?
POTASSIUM HYDROXIDE is banned in EU. It has concentration limits or usage restrictions in UK. The ingredient is freely allowed in JP, US.
Are there alternatives to POTASSIUM HYDROXIDE?
Due to regulatory restrictions on POTASSIUM HYDROXIDE, cosmetic manufacturers often use alternative ingredients with similar functions. For buffering, alternatives may include other approved ingredients in the same category. Consult product labels for specific formulations, and look for products compliant with your region's regulations.
Disclaimer
The information on this website is for educational and informational purposes only and is not intended as medical advice. While we strive for accuracy based on official government databases, cosmetic regulations change frequently. Always consult with a qualified professional or refer to the latest official regulatory documents for compliance. We are not responsible for any actions taken based on the information provided here.