Ingredient
Ammonium Hydroxide / Hydrogen Peroxide
What is Ammonium Hydroxide / Hydrogen Peroxide?
Ammonium hydroxide and hydrogen peroxide are chemicals commonly used in hair care products, particularly in hair dyes and bleaching agents. Ammonium hydroxide is a solution of ammonia in water, while hydrogen peroxide is a clear liquid with strong oxidizing properties.
These ingredients are used in hair care products to help color penetrate the hair shaft (ammonium hydroxide) and to bleach or lighten hair color (hydrogen peroxide). While effective for these purposes, their presence in cosmetic products has been debated due to potential irritation and damage to hair and scalp.
Consumers should be aware of these substances in hair care labels, particularly if they have sensitive skin or have previously experienced irritation from hair treatments.
Commonly found in: Hair dyes, Bleaching creams, Permanent wave solutions, Conditioners
What to watch
- Ammonium hydroxide can cause skin and eye irritation.
- Hydrogen peroxide may cause hair damage and scalp irritation if overused.
Both chemicals are allowed in cosmetics but must meet safety standards to avoid irritation.
Studies acknowledge their effectiveness in hair care but highlight risks of irritation and damage.
These chemicals are synthetic and typically considered vegan.
Scout's take
Ammonia opens the hair cuticle and hydrogen peroxide oxidizes natural pigment. The combination is a strong skin and respiratory irritant and can cause scalp burns.
More from Scout's analyses
Ammonia opens the hair cuticle and hydrogen peroxide oxidizes natural pigment — together they are the harsh chemistry that makes permanent dye work. The combination is a strong skin and respiratory irritant, can cause scalp burns, and is the source of the characteristic dye fume exposure during application.
from the analysis of L'Oréal Paris Féria Downtown BrownAmmonia opens the hair cuticle and hydrogen peroxide oxidizes natural pigment — the harsh chemistry that drives permanent dye penetration. The combination is a strong skin and respiratory irritant and can cause scalp burns. Magic Root is marketed as 'low ammonia' but still relies on this oxidative system.
from the analysis of L'Oréal Paris Magic Root Permanent Dark BrownFound in 5 products
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