Is Ammonia in Hair Dye Harmful? Ammonia-Free Alternatives Explained

Why is ammonia used in hair dye?

Ammonia (INCI: Ammonia, often present in products as an aqueous solution – Ammonium Hydroxide) serves two key technical functions in permanent oxidative hair dyes:

1. Raising the pH (alkalization) – ammonia raises the pH of the dye mixture to around 9–11. This high pH lifts the cuticle scales of the hair, allowing the dye molecules to penetrate into the cortex.
2. Activating hydrogen peroxide – combined with the oxidant (H₂O₂), ammonia drives the oxidation reaction that breaks down the hair's natural pigments (melanins) and polymerizes the synthetic dyes inside the hair shaft.

Without an alkalizing agent, permanent coloring would be impossible or far less effective. Ammonia is preferred by many manufacturers because of its volatility – it evaporates from the formula after coloring, leaving the pH closer to its natural level.

Is the ammonia in hair dye harmful to your health?

This question requires distinguishing between several types of risk:

Irritation of the skin and mucous membranes

Ammonia is a strong irritant. During coloring it can cause:

• burning or itching of the scalp,
• irritation of the eyes and nose (the characteristic sharp smell),
• irritation of the respiratory tract – especially in poorly ventilated rooms.

That is why coloring should always be done in a well-ventilated room. People with bronchial asthma or airway hyperreactivity should take particular care or consider alternatives.

Damage to the hair structure

The high pH caused by ammonia lifts the hair cuticle and can lead to:

• loss of moisture and proteins (keratins) from the hair cortex,
• weakening of the hair structure with frequent coloring,
• dryness, brittleness and difficulty combing.

These effects are stronger the higher the ammonia concentration and the longer the exposure time. Proper aftercare following coloring (conditioners, protein masks) can partly counteract them. It's worth looking for products for color-treated hair that support structural repair – check out the categories under hair conditioners.

Systemic toxicity at typical cosmetic exposure levels

Regulation (EC) No 1223/2009 permits the use of ammonia in cosmetics. As a cosmetic ingredient, ammonia is listed in the CosIng database with defined conditions of use. In its safety assessments of hair coloring products, the SCCS (the EU Scientific Committee on Consumer Safety) confirms that typical cosmetic exposure (contact with the scalp for 30–60 minutes, a few times a year) does not pose a significant systemic risk for healthy adults.

The exceptions are people with exceptionally sensitive scalps, pregnant women (caution due to the volatility of ammonia vapors, although studies do not confirm a significant risk under normal use) and people with respiratory conditions.

Ammonia-free dyes – what's the difference?

Dyes labeled ammonia-free use other alkalizing agents instead of ammonia – ones that are less volatile and have a less irritating odor:

• Ethanolamine (Ethanolamine, MEA) – the most popular substitute. It raises pH much like ammonia, but it is non-volatile, which eliminates the sharp smell. However, it stays in the formula longer, so it can act on the hair cuticle for an extended period.
• Monoisopropanolamine (MIPA) – similar properties to MEA.
• Carbonates (e.g. Ammonium Bicarbonate) – milder alkalizing agents, used in gentle formulas.
• Arginine (L-Arginine) – an alkaline amino acid used in advanced premium formulas as a gentle alternative.

Are ammonia-free dyes actually safer?

This is where you need to be careful with the interpretation:

• The absence of ammonia does not mean the absence of an alkaline pH – ammonia-free dyes also raise the hair's pH, though often less than classic ammonia-based formulas.
• Ethanolamine (MEA) – the most common ammonia substitute – raises its own controversies. Studies suggest it may be more damaging to the hair's protein structure than ammonia, because it penetrates the cortex and is harder to evaporate. The allergenic potential of MEA is not zero.
• Smell – the absence of ammonia's sharp odor is a genuine advantage for comfort and for people sensitive to fumes, but it is not automatic proof of better safety for the skin or hair.
• Color longevity – ammonia-free dyes can produce slightly less long-lasting color, particularly when lightening.

When choosing a dye, it's worth checking the INCI list – you'll find all the key ingredients in the PurScore ingredient encyclopedia. By comparing products in the hair dyes category, you can see which alkalizing agent the manufacturer used.

How to minimize the risks when coloring your hair

1. Ventilation – color in a well-ventilated room or with a window open.
2. Allergy test – always do a 48-hour patch test before using a product for the first time and whenever you switch brands.
3. Skin protection – wear the gloves supplied with the kit and protect the skin around your hairline with a cream or petroleum jelly.
4. Less frequent coloring – coloring every 6–8 weeks instead of every 3–4 weeks significantly reduces your total exposure to alkaline and oxidizing ingredients.
5. Aftercare – use conditioners and masks that seal the cuticle and rebuild the hair's proteins.

Summary

Ammonia in hair dyes is a regulatory-approved ingredient and, under normal use, does not pose a significant systemic health risk. Its main drawbacks are the sharp odor that irritates the airways and the potential damage to the hair structure with frequent coloring. Ammonia-free dyes eliminate the unpleasant smell, but they are not automatically safer – they use other alkalizing agents (primarily ethanolamine), which have their own properties. The best strategy is to make an informed choice based on the full INCI list, follow proper aftercare and keep coloring as infrequent as possible.

This article is for informational purposes only and does not constitute medical advice. If you are allergic to dye ingredients or have scalp problems, consult a dermatologist before coloring.

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