Potassium hydroxide (E525)
- Food Fine
- Cosmetics Caution
What is Potassium hydroxide (E525)?
Potassium hydroxide (E525) is used in small amounts to adjust acidity, for example when processing cocoa. In food it's diluted and neutralised, so it isn't caustic. It's fine; only the concentrated chemical causes burns.
What does Potassium hydroxide do in cosmetics?
In cosmetics, potassium hydroxide adjusts pH and helps make soap, and in most products it is fully neutralised. The caution is for strongly alkaline products such as hair removal creams, hair straighteners and callus removers, where some can stay active. With those, keep contact short, avoid your eyes and follow the directions closely.
What is Yasno’s verdict on Potassium hydroxide?
Yasno’s verdict on Potassium hydroxide: In food: Fine. No meaningful concern at normal amounts. In cosmetics: Caution. Some evidence of a concern, it depends on the amount, or it is genuinely worth knowing. A Caution always has a specific, sourced reason.
Is Potassium hydroxide allowed in the EU?
EU status of Potassium hydroxide: In food: Permitted as a food additive. In cosmetics: Restricted in cosmetics (limits and conditions apply). Conditions and limits come from the regulation cited below. Yasno summarises them and does not replace the legal text.
| Where | EU | US |
|---|---|---|
| Food | Permitted as a food additive | Regulated as a food additive by the US FDA |
| Cosmetics | Restricted in cosmetics (limits and conditions apply) | Not recorded |
What else is it called?
- Caustic potash
- Potash lye
- Potassium hydrate
Sources
- EU Food Additives Register — POL-FAD-IMPORT-3222, European Commission (DG SANTE), 2011
- 2021 Cosmetic Ingredient Review assessment, Cosmetic Ingredient Review, 2021
- P1066 Supporting Document 3 – Safety and Food Technology, Food Standards Australia New Zealand, 2026
Always check the physical label. Yasno describes evidence and regulatory status. It never says a product is free of an allergen or safe for you, and it is not medical advice.
Yasno reads the whole label from a photo and explains every ingredient like this. It is coming soon to the App Store.