Self-Tanner and DHA in the Formula — How It Works, How to Apply It and What to Watch Out For

What is DHA and why will you find it in every self-tanner?

DHA (dihydroxyacetone) is a simple sugar (a monosaccharide) responsible for the brown tone the skin takes on after applying a self-tanner. On the INCI list it appears as Dihydroxyacetone. It is not a dye in the traditional sense — it does not settle on the surface of the epidermis like a pigment, but instead enters into a chemical reaction with the amino acids of the stratum corneum.

DHA has been used in cosmetics since the 1960s. Today you will find it in mousses, lotions, creams and self-tanning sprays — from drugstore products to professional spray-tan booths. Before you reach for a product, though, it is worth understanding exactly what happens on your skin.

The Maillard reaction — the chemistry behind the colour

The tan you get from a self-tanner is the result of the Maillard reaction — the very same one that gives bread its brown colour during baking or meat its colour on the grill. DHA reacts with free amino groups (mainly lysine and arginine) in the keratin of the epidermis, forming brown compounds called melanoidins.

Key facts about this reaction:

• It takes place only in the dead cells of the stratum corneum — it does not penetrate any deeper.
• The colour develops gradually over 2–6 hours after application.
• The full effect is visible after 24 hours.
• The tan lasts 5–7 days, fading along with the natural exfoliation of the epidermis.
• It does not stimulate melanin production — it is a purely surface-level chemical reaction.

Important: a tan from a self-tanner does not protect against UV radiation. Melanoidins do not provide the protective function of natural melanin pigment. You still need an SPF filter — read more about choosing the right protection in the article SPF in creams — how much do you really need?

Erythrulose — a gentler alternative

Erythrulose (INCI: Erythrulose) is another sugar used in self-tanners, often combined with DHA. It works on the same principle — reacting with the amino acids of the epidermis — but more slowly and more gently.

Differences between DHA and erythrulose:

• Speed: DHA produces colour in 2–6 h, while erythrulose needs 24–48 h.
• Shade: DHA can give a yellowish-orange tone, while erythrulose produces a warmer, more natural brown.
• Longevity: The colour from erythrulose fades more evenly.
• Tolerance: Erythrulose is gentler and less likely to irritate the skin.

The best self-tanners combine both ingredients: DHA delivers a fast effect, while erythrulose smooths it out and extends it. Check the detailed profiles of these substances in our ingredient encyclopedia.

How to apply a self-tanner correctly?

Even the best self-tanner leaves streaks when applied carelessly. Here is a tried-and-tested routine:

1. Exfoliate 24 h beforehand: Slough off dead skin (especially elbows, knees and ankles). An uneven stratum corneum = uneven colour.
2. Moisturise dry areas: Apply a thin layer of a light lotion to elbows, knees and ankles — this reduces DHA absorption in these spots.
3. Apply with a mitt: Use a dedicated self-tanning mitt. Apply the product in circular motions, section by section.
4. Hands last: Wipe your hands with a damp cloth after application — orange palms are a classic mistake.
5. Drying time: Wait at least 10 minutes before getting dressed. Wear loose, dark clothing on the first day.
6. No bathing for 6–8 h: Give the Maillard reaction time to fully develop the colour.

INCI names — what to look for on the label

When choosing a self-tanner, it pays to read the formula. Here are the key entries:

• Dihydroxyacetone — the main self-tanning ingredient (DHA).
• Erythrulose — a supporting self-tanning sugar that improves the naturalness of the colour.
• Aloe Barbadensis Leaf Juice — moisturises and soothes the skin.
• Glycerin, Hyaluronic Acid — humectants that prevent over-drying.
• Caramel — a cosmetic dye that helps with even application (it has no self-tanning effect).

Avoid products with a high alcohol content (Alcohol Denat. high on the INCI list) — they dry out the skin and can worsen the evenness of the tan.

Is DHA safe?

DHA is one of the most thoroughly studied cosmetic ingredients. The SCCS (Scientific Committee on Consumer Safety) of the European Commission considers it safe at concentrations of up to 10% in products applied to the skin.

The most common concerns and the facts:

• Absorption: DHA reacts in the stratum corneum and does not penetrate the living layers of the skin. Systemic absorption is minimal.
• Free radicals: In vitro studies suggest that, after reacting with amino acids, DHA may generate free radicals when exposed to UV. This is all the more reason not to skip an SPF filter.
• Inhalation: With sprays and spray-tan booths there is a risk of inhaling DHA. Protect your mouth and nose, or opt for cream/mousse forms.
• Allergy: Allergic reactions to DHA are very rare, but possible. If you have sensitive skin, do a patch test on a small area.

Self-tanner vs. a real tan — summary

A DHA self-tanner is a safe cosmetic alternative to tanning beds and long sunbathing sessions. It does not expose you to UV radiation, it does not accelerate photoaging, and it does not increase the risk of skin cancer. The only thing it does not provide is protection — which is why a sunscreen remains a must.

Looking for a self-tanner with a good formula? Use the PurScore search tool to compare products and find the one with the shortest, cleanest INCI list.