The ingredient, explained

Kojic Acid

An ingredient studied in topical combinations for melasma.

AntioxidantTyrosinase inhibitor / brightening

Explore connections

Ingredient guide

What it is and what it does

5-Hydroxy-2-hydroxymethyl-4-pyrone

About this ingredient: EU CosIng ingredient registry (via Open Beauty Facts taxonomy) ↗

Antioxidant: Limits oxidation, including deterioration of formulation ingredients. This label alone does not show a clinical antioxidant effect in skin.
Tyrosinase inhibitor / brightening: Research category for changes in pigmentation or uneven skin tone. The label does not establish that a finished product changes pigmentation.

Function definitions: European Commission ingredient function definitions (SCCNFP/0299/00, pages 16 to 20) ↗ · Original niacinamide study: Pigmentation and hyperpigmented spots ↗

Registry functions describe possible formulation roles, not results for a finished product. A dictionary entry is not an approval or a safety assessment.

A closer look

What the research shows

Human research on a combination

A 30-participant pilot trial compared 2% kojic acid plus 5% alpha-arbutin with a triple-combination medicinal cream for 12 weeks. Objective pigmentation measures did not significantly differ; physician grading favoured the medicinal cream, which caused more erythema and stinging.

What this does not tell us

The trial did not test kojic acid alone or include a vehicle-only group, and participants used sunscreen. Its small size does not establish equivalence to medical treatment or the efficacy of another cosmetic.

Sources for this summary. PubMed 39555866 ↗

Research review checked Sep 30, 2026

Selected primary sources were reviewed for the existing research brief on 30 September 2026, with exact ingredient, route and combination limitations recorded. This was a bounded editorial review, not a systematic search.

Ingredient research is not proof that a product containing this ingredient works.