Kojic Acid for Dark Spots: Effects, Research and New EU Limits

Note: image partly or fully created with AI.

The short answer

Kojic acid is a fermented ingredient that inhibits tyrosinase and can therefore visibly lighten dark spots – more moderately than hydroquinone, but with a higher potential for irritation. Since 2025, the EU Cosmetics Regulation has limited its use to a maximum of 1% in face and hand care, after the Scientific Committee on Consumer Safety (SCCS) raised concerns about higher concentrations. Visible effects take several weeks and only work with consistent sun protection.

What is kojic acid?

Kojic acid (INCI: Kojic Acid) is produced when rice, soybeans or other carbohydrates are fermented by fungi of the genus Aspergillus – the same microorganisms that play a role in making sake and miso. The substance was discovered back in the 1980s in Japan, where it has since been used in East Asian skincare to lighten dark spots. Because it comes from a natural fermentation process, kojic acid is generally considered an ingredient suitable for certified natural cosmetics under the COSMOS standard.

How does kojic acid work against dark spots?

Kojic acid binds copper ions in the active centre of tyrosinase, the key enzyme in melanin production, thereby slowing its activity. Less active tyrosinase means less newly formed melanin – existing dark spots slowly fade and new ones form less often. This mechanism is similar to that of arbutin and azelaic acid, but differs from tranexamic acid, which acts one step earlier in the signalling cascade. In practice, kojic acid is rarely used on its own, but is usually combined with vitamin C, liquorice root extract or mild fruit acids, which complement its effect.

New EU limits: what has changed?

With Regulation (EU) 2024/996, the EU Commission included kojic acid in Annex III of the Cosmetics Regulation for the first time – the list of substances subject to restrictions. The basis was an SCCS opinion from March 2022, which considered kojic acid in leave-on skin-lightening products safe only up to a maximum of 1% and exclusively in face and hand care. Since 1 February 2025, non-compliant products may no longer be placed on the market, and since 1 November 2025 they may no longer be made available to consumers. Formulations with higher doses or for use on the whole body are therefore no longer permitted. If you currently have an older kojic acid product on your shelf, check the INCI list and the concentration information.

What does the research show, critically assessed?

Clinical comparative studies show that kojic acid alone works noticeably on melasma and dark spots, but more weakly than hydroquinone and usually also more weakly than high-dose azelaic or tranexamic acid. In combination products – for example with glycolic acid or vitamin C – the brightening is more pronounced in studies than with kojic acid alone. Two points should be viewed critically: first, compared with niacinamide or azelaic acid, kojic acid is considered rather irritating and is regularly cited in dermatological literature as a trigger of contact dermatitis, especially with frequent use or on sensitive skin. Second, the pure ingredient is chemically unstable: it oxidises in light and air, turns brownish and loses efficacy. Many formulations therefore use the more stable derivative kojic acid dipalmitate – for which, however, there are considerably fewer independent efficacy studies than for pure kojic acid.

In practice: adding kojic acid to your routine the smart way

Sun protection is the real foundation

Without daily UV protection, the skin constantly produces new melanin – and any brightening ingredient then fizzles out largely without effect. The mineral The Sun Kiss SPF 30 is suitable as a daily basis so that pigmentation care can work at all.

Add antioxidant cell protection

Oxidative stress also encourages new dark spots to form. The Hydrating Serum with Alteromonas ferment extract supports cellular defence and combines well with targeted brightening care.

Keep the barrier stable to prevent irritation

Since kojic acid can cause irritation, an intact skin barrier is important before active ingredients are used. The Day Cream with ceramides and sea buckthorn supports exactly that and is a soothing final step in your daytime routine.

Frequently asked questions about kojic acid

Is kojic acid permitted in certified natural cosmetics?

Yes, as a fermentation product, kojic acid is generally considered a COSMOS-compliant ingredient. Since 2025, the EU-wide maximum of 1% in face and hand care also applies, which is binding for all cosmetic products regardless of label.

How quickly does kojic acid work on dark spots?

In studies, the first visible effects usually appear after six to eight weeks of regular use; noticeable improvements in stubborn spots or melasma often take several months.

Can kojic acid irritate the skin?

Yes, compared with milder ingredients such as niacinamide, kojic acid is considered more irritating. A gradual start with a low frequency and building up a stable skin barrier are recommended, especially for sensitive skin.

Conclusion

Kojic acid is a scientifically plausible but not particularly strong tyrosinase inhibitor – more effective in combination than alone, and since 2025 more clearly limited from a regulatory point of view by the new EU maximum of 1% in face and hand care. If you rely on the fermented ingredient, see it as one building block alongside consistent sun protection and a stable skin barrier – for example with Cosmenia's The Sun Kiss SPF 30 and The Day Cream as the basis of a pigmentation-conscious routine.