evidently.
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Kojic Acid

KOJIC ACID

A fermentation-derived brightener with decent trial support and a known sensitivity trade-off.

antioxidantCAS 501-30-4

Why it works

Produced by fungi during fermentation (including in sake brewing), kojic acid chelates the copper that the pigment enzyme tyrosinase needs to function, slowing melanin production.

Concentration matters

Trials used 1–4%; the EU now restricts cosmetic use to 1% (SCCS-reviewed).

The evidence, by concern

Dark spots

Good evidence

Trial-supported brightening, usually as a co-star

How sure are we
good
How much it helps
modest but real
Do studies agree
mostly agree

Randomized trials — often combining kojic acid with hydroquinone or glycolic acid — show meaningful melasma improvement, with kojic-containing arms modestly outperforming those without in split-face testing. Solo evidence at today's 1% cap is thinner; expect it to assist rather than lead.

The receipts

4 trials/reviews indexed · showing most cited

Safety, without the fear

Anchored to regulatory assessments — not hazard lists. Dose makes the poison; these are the conclusions at real-world cosmetic use.

SCCS · EU scientific safety committee

SCCS deemed kojic acid safe at up to 1% — now the EU limit for face and hand products. Contact sensitization is documented even at 1% after months of continuous use, so watch for developing redness or itch and patch-test if reactive.

Source →
Spotted an error, or a study we missed? Claims were fact-checked against the cited literature in August 2026; independent clinical sign-off is pending — corrections welcome.