E525 (Potassium Hydroxide) is an alkaline inorganic chemical compound also called caustic potash, which is obtained by an electrolytic process from potassium chloride.

It appears as a white powder or whitish flakes.

What it is used for and where

Food

Ingredient included in the list of European food additives as E525 as a preservative, acidity regulator.

Medical

Potassium hydroxide is a strong alkaline agent known to dissolve keratin, effective for the treatment of genital warts and in the paediatric treatment of Molluscum contagiosum.  It is used in dermatology as a diagnostic test to identify fungal elements in skin scrapings.

Cosmetics

It is a restricted ingredient as III/15a, 15d a Relevant Item in the Annexes of the European Cosmetics Regulation 1223/2009

Buffering agent. It is an iingredient that can bring an alkaline or acid solution to a certain pH level and prevent it from changing, in practice a pH stabiliser that can effectively resist instability and pH change.

Cosmetic safety

The SCCS cosmetics expert committee considers potassium hydroxide to be safe for use as a callus softener/eliminator at a maximum concentration of 1.5% by weight. Other potential uses of potassium hydroxide in cosmetic products cannot be evaluated without further documentation.  The safe use of cosmetic products containing free potassium hydroxide in concentrations of 0.5% and above depends on responsible risk management (warnings and broad indications for use) (1).

Other uses

• Tomato peeling
• Counteracting microorganisms associated with poultry processing
• Alkaline flow in glass production
• Chemical activator

• Molecular Formula   KOH or HKO
• Molecular Weight    56.106
• CAS  1310-58-3
• UNII    WZH3C48M4T
• EC Number  215-181-3

References_____________________________________________________________________

(1) Opinion of the Scientific Committee on Consumer Safety on o-aminophenol (A14) (europa.eu)