The Lab
Specimen No. 0207
CautionDerivedskin lighteningantioxidant

Kojic Acid

CAS 501-30-4 · Kojic acid · KA · 5-hydroxy-2-(hydroxymethyl)-4-pyrone

A fungal-derived skin-lightening agent that the EU deems safe up to 1 percent, but which is a documented skin sensitizer and is under scrutiny for possible thyroid-related endocrine effects.

high confidence
Researched July 7, 2026

Concerns

  • Kojic acid has a high sensitizing potential: in patch testing of users of 1 percent kojic-acid skin-care products, 5 of 8 reacted to it (Nakagawa 1995, PMID 7720390)
  • The EU SCCS final opinion (SCCS/1637/21) concluded kojic acid is safe up to 1 percent as a skin-lightening agent, while explicitly weighing concerns about its potential endocrine-disrupting properties, reported to interfere with thyroid function such as iodine organification and uptake
  • Because kojic acid is sometimes added to peeling agents, a weakened skin barrier may increase dermal absorption and is an additional consideration (SCCS/1637/21)

Regulatory flags

  • IARC Class: NL
  • EDC Status: Under SCCS review (potential thyroid effects)
  • Regulatory: EU SCCS: safe up to 1% (SCCS/1637/21) with potential endocrine concerns flagged
  • Evidence Grade: B

Commonly found in

Skin-brightening serumAnti-dark-spot creamFade creamFacial soap

Research disclaimer: This rating is based on available peer-reviewed research and regulatory assessments at the time of publication. It is not medical advice. Consult a qualified professional for personal health or skin concerns.

Check another ingredient

Search our database of scored cosmetic, food, and household ingredients — or scan a full product label.

Open the Ingredient Lab

Embed this verdict

LabelCleared verdict badge: Kojic Acid — Caution
<a href="https://labelcleared.com/lab/kojic-acid"><img src="https://labelcleared.com/embed/kojic-acid/badge.svg" alt="LabelCleared verdict badge: Kojic Acid — Caution" height="34"></a>