Ingredient dictionary

Potassium Hydroxide

Also listed as: Caustic Potash, KOH

Potassium Hydroxide is a strong alkali used to raise pH and help make soap from fatty oils in cleansers and shaving products. It is on the label of 31 products in our library. Checked against our library November 6, 2026.

The catch: none for most people; check the full product list if your skin reacts easily.

What Potassium Hydroxide does

Adjusts the pH of a formula
Helps make potassium soap from fatty oils
Helps neutralize acidic ingredients

Potassium Hydroxide is usually made by running electricity through a potassium chloride solution, a process called electrolysis. It is the potassium cousin of sodium hydroxide, the strong base used in bar soap. In raw form it can irritate skin, so manufacturers use it in finished products in carefully controlled amounts.

Formulators use it to raise pH, the measure of how acidic or alkaline a product is. It also turns fatty oils into potassium soaps, which are softer and more soluble than sodium soaps, so they suit liquid cleansers and creamy shaving products. In finished products it feels smooth and rinses cleanly.

Good for

Shoppers who like creamy liquid cleansers and shaving creams, since finished products balance its strength for everyday use.

Be careful if

Nothing in particular for most skin types.

Frequently asked questions

Is Potassium Hydroxide safe in skincare?

In finished cosmetics it is used at low levels, balanced so the product stays in a comfortable pH range. Raw potassium hydroxide can irritate, so it is handled with care during manufacturing. If you have sensitive skin, patch test new products.

Is potassium hydroxide the same as lye?

Lye is a general term for strong alkaline substances used in soapmaking. Sodium hydroxide is the common lye for bar soap, and potassium hydroxide is the lye for softer, liquid soaps. Both are strong bases and need careful handling in raw form.