Potassium Hydroxide
Reviewed by Emma · Last updated 18 Aug 2026
Also known as: lye, caustic potash
Potassium hydroxide is a highly alkaline ingredient (also known
EWG Safety Score
What Is Potassium Hydroxide?
Potassium hydroxide is a highly alkaline ingredient (also known as lye) used in small amounts in cosmetics to modulate the pH of a product. It’s also used as a cleansing agent, most often in pure soaps or soap hybrid products. In higher concentrations, potassium hydroxide can aggravate skin, even if used in rinse-off products.
Clinical Evidence & References
Published Research
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Ullman's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. [https://onlinelibrary.wiley.com/doi/book/10.1002/14356007]
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https://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+1234 [https://pubchem.ncbi.nlm.nih.gov/compound/Potassium-Hydroxide]
How widely it's used
Regulatory information
Standardised cosmetic-ingredient identifiers used by regulators.
Show identifiers
- INCI Name
- POTASSIUM HYDROXIDE
- INN Name
- potassium hydroxide
- EC Number
- 215-181-3
- Pharmacopoeia Name
- kalii hydroxidum
- Function
- Buffering
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