What Is Polydihydroxyindole?
Polydihydroxyindole is a dark brown polymer created from the small molecule 5,6-dihydroxyindole, one of the building blocks that nature uses to make melanin, the pigment that gives skin and hair their color. In the lab the ingredient is produced by allowing 5,6-dihydroxyindole to oxidize and join together in long chains, a process called oxidative polymerization. The result is a stable, water-insoluble powder that disperses well in creams, lotions and gels.
Interest in the material grew in the 1990s when researchers looked for safe melanin-like substances to add subtle color, boost photoprotection and improve the feel of cosmetic formulas. Today manufacturers synthesize polydihydroxyindole under controlled conditions rather than extracting it from animal sources, which keeps production consistent and vegan-friendly.
You will most often see the ingredient in self-tanning lotions, bronzing drops, tinted moisturizers, anti-aging serums and certain specialty masks where a smooth skin finish is desired.
Polydihydroxyindole’s Cosmetic Benefits/Uses
In topical products polydihydroxyindole is valued for one main role: skin conditioning. It forms a lightweight film on the surface that helps skin feel softer and smoother, supports an even appearance and can subtly mask minor tone irregularities. The ingredient also blends easily with other actives and pigments which allows formulators to create products that glide on effortlessly and leave a comfortable, non-sticky after-feel.
Who Can Use Polydihydroxyindole
Polydihydroxyindole suits most skin types including oily, dry, combination and mature skin because it forms a breathable film that is not heavy or greasy. Sensitive or highly reactive skin may wish to proceed cautiously since any pigment-like material can occasionally provoke a response in those prone to redness or allergies.
The ingredient is produced through lab synthesis with no animal derivatives so it meets vegan and vegetarian standards.
No studies have flagged issues for pregnant or breastfeeding women. That said this is not medical advice and anyone expecting or nursing should check with a doctor before adding new skincare products.
Polydihydroxyindole does not make skin more sensitive to sunlight. In fact its melanin-mimicking nature can lend a mild protective tint, though it is no replacement for broad-spectrum sunscreen.
Potential Side Effects/Adverse Reactions
Responses to topical polydihydroxyindole vary from person to person. The points below outline possible, though uncommon, effects when the ingredient is used in properly formulated products most people will not experience these issues.
- Temporary skin staining if applied in high concentration or not evenly spread
- Mild contact irritation such as redness, itching or burning in sensitive individuals
- Allergic contact dermatitis in those allergic to indole-based compounds
- Eye irritation if the product accidentally gets into the eyes
- Acne flare-ups in very acne-prone skin when combined with rich, occlusive bases
If any adverse reaction occurs stop use immediately and seek advice from a healthcare professional.
Comedogenic Rating
Rating: 1 / 5
Polydihydroxyindole itself is a lightweight, film-forming polymer that does not clog pores in standard cosmetic concentrations. It is water-insoluble yet sits on the surface rather than penetrating follicular openings, which keeps its pore-blocking potential low. The score is not zero because any pigment-like powder can trap sebum if packed on in very high amounts or if blended into heavy butters and waxes.
Suitable for acne-prone and breakout-prone skin, provided the overall formula is non-occlusive.
As with many color additives, the real comedogenic risk often comes from the carrier oils, thickeners and emollients used alongside the polymer, so scan the full ingredient list if you are highly clog-prone.
Summary
Polydihydroxyindole is a lab-made, melanin-mimicking polymer that conditions skin by laying down a soft, flexible film. This film smooths texture, evens visual tone and helps other pigments spread more uniformly. Thanks to these abilities you will find it most often in self-tanners, bronzing drops and tinted serums, though it still remains a niche ingredient compared with mainstream conditioners like glycerin and dimethicone.
Current data show the polymer is low risk for irritation and almost non-comedogenic. It is vegan friendly and considered safe for everyday use in leave-on products. As with any new skincare ingredient, patch testing is wise to make sure your skin agrees before you apply it more widely.