Ingredient dictionary

Ammonium Hydroxide

Also listed as: Ammonia Water, Aqua Ammonia

Ammonium Hydroxide is ammonia dissolved in water. Formulators use it mainly as a pH adjuster, to bring a formula into a comfortable range. It is on the label of 4 products in our library. Checked against our library November 6, 2026.

What Ammonium Hydroxide does

Adjusts pH to a skin-friendly range
Neutralizes acidic ingredients in a formula

Ammonium Hydroxide is made by dissolving ammonia gas in water. The result is a clear liquid that is alkaline, meaning it acts as a base. Chemists call it an alkali. Formulators use small amounts to raise pH or to neutralize acidic ingredients, such as certain fatty acids. Those fatty acids help build creamy textures, and the ammonia turns them into salts that blend more easily into water-based formulas.

In a finished product the amount is small, and it works quietly in the background to keep the formula balanced. Concentrated ammonia has a sharp smell, so it is handled with care during manufacturing. In our catalog it turns up most often in eyeliner, where a stable, well-balanced formula helps the product apply smoothly.

Good for

Suits anyone curious about the pH adjusters in their eyeliner or makeup. Most people tolerate it well at the levels used in finished products.

Frequently asked questions

Is ammonium hydroxide the same as ammonia?

They are closely related. Ammonia is the gas, and ammonium hydroxide is that gas dissolved in water. In cosmetics, the dissolved form is what gets used, since it is easier to measure and blend into liquid formulas.

Is ammonium hydroxide safe in eyeliner?

Ammonium hydroxide is generally well tolerated at the low levels used in finished cosmetics, and it is used as a pH adjuster. If you have sensitive eyes or notice stinging, stop using the product and speak with a doctor or dermatologist.