Ammonium Hydroxide

What is Ammonium Hydroxide?

Ammonium hydroxide is an aqueous solution of ammonia gas dissolved in water, forming a weak alkaline base through a synthetic process from industrial ammonia production. In cosmetics, it appears primarily in hair colorants, relaxers, and select skincare formulations like cleansers or toners. It functions by releasing ammonia molecules that elevate pH levels, enabling hair cuticles to swell for better dye penetration and color fixation. As a buffering agent, it resists pH shifts during storage or use, preserving product integrity. In alcohol-containing items such as sprays or fragrances, it denatures ethanol, rendering it unfit for consumption while subtly affecting texture and evaporation. Typical concentrations remain low to support efficacy without excess alkalinity.

Comedogenic Rating 0/5 Low risk of clogging pores
EWG Safety Rating 2-3 View on EWG →
PubChem View on PubChem →

Roles in Formulation

This ingredient serves the following purposes in cosmetic formulations:

Denaturant
Makes ethanol undrinkable (for regulatory/tax purposes) and can influence dry-down and sensory feel in alcohol-based sprays, toners, and fragrances.
PH adjuster
Raises or lowers pH to the target range, supporting ingredient performance, preservative efficacy, stability, and user comfort.
Buffering agent
Maintains the pH stability of a formulation.

Benefits

Supports stable pH for better ingredient performance and shelf life.

Facilitates even hair color application by opening cuticles.

Renders alcohol-based products safe by making them undrinkable.

Who It's For

A quick guide for who this ingredient may suit (and who should be cautious).

Who May Benefit Who Should Avoid
Individuals using permanent hair dyes for consistent results.
Those with sensitive or damaged skin prone to irritation.
Users of toners or sprays needing smooth sensory feel.
Individuals with ammonia sensitivity or allergies.
People seeking stable, long-lasting cosmetic formulas.
People with open wounds or eye area applications.

Safety Notes

  • Regulated for safe use in low concentrations by cosmetic authorities.
  • Rinse thoroughly to minimize potential eye or skin contact.

Frequently Asked Questions about Ammonium Hydroxide

What is ammonium hydroxide used for in cosmetics?

It adjusts pH, buffers stability, and denatures alcohol in hair dyes, toners, and sprays.

Is it safe for skin?

Generally safe in low cosmetic concentrations, though it may irritate sensitive skin.

Does it clog pores?

It has a comedogenic rating of 0, unlikely to contribute to acne.