What is kojic acid?
Kojic acid is an ingredient produced by fungi during fermentation. In cosmetics it's used because it acts on tyrosinase, an enzyme involved in making skin pigment, so you'll find it in products aimed at the look of uneven tone. The EU's consumer safety scientists consider it safe in cosmetics at up to 1 per cent, with an extra note of caution for skin with a weakened barrier.
Where it comes from
Kojic acid is a fungal metabolite, made by the kinds of moulds used in fermenting rice and other foods. It's why our shop page describes it as coming from fermented rice. What ends up in cosmetics is a purified ingredient.
What it does
Melanin, the pigment that gives skin its colour, is made with the help of an enzyme called tyrosinase. Kojic acid can inhibit that enzyme, which is why it's used in products aimed at uneven-looking tone.
What this looks like on real faces is harder to say. Research often uses leave-on creams over months, sometimes in combination with other ingredients. DermNet's page on melasma lists kojic acid among other topical agents that have been tried, alongside much stronger prescription options. So a short-contact mask shouldn't be expected to do what a months-long routine might.
Is kojic acid safe?
The most thorough public review we found is by the EU's Scientific Committee on Consumer Safety (SCCS). Its 2022 opinion, as corrected that June, went over concerns about possible hormone-related effects, especially on the thyroid, and concluded that kojic acid is safe in cosmetic products at up to 1 per cent. A few details are worth knowing:
- It changed its view along the way. Earlier versions of the opinion read differently, including a preliminary one that was less reassuring. If you search, you'll see articles quoting those. The June 2022 correction is the latest version we could find.
- Skin barrier matters. The SCCS raised an extra concern about products that combine kojic acid with peeling agents, because a weakened barrier may absorb more. That's a good reason not to use it on irritated, broken or freshly exfoliated skin.
- Allergy is uncommon. The same opinion considered allergic contact dermatitis from kojic acid to be very low in occurrence, but not impossible.
- It only covers cosmetics on skin, and not derivatives such as kojic acid dipalmitate.
Kojic acid in our jars
Of our jars, Hyaluronic Acid contains it: it's fifth on its label. The shop page says it "helps the look of uneven tone and dark spots". The label doesn't state a percentage, so we can't tell you the exact strength in a jar. What we can tell you is how to use it with care: patch test first, keep it off broken or irritated skin, and don't use it on the same day as exfoliating acids.
If you'd rather avoid kojic acid altogether, the labels of Rose and Tea Tree don't list it. Check the full list on any formula page before you buy.
What we don't say
We aren't selling lighter skin. "Even-looking" and "lighter" are not the same thing, and every skin tone can have patches that are darker or uneven. We also won't claim a jelly mask will fade a mark. If you have a new or changing spot, the priority is to get it looked at. See dark spots on your face.
Pregnancy
A 2022 review of topical products in pregnancy says kojic acid has low absorption and no known risk in animals, but that there's no human data, and it doesn't recommend it for now. See skincare in pregnancy and talk to your doctor.
Questions
Is kojic acid safe to use every day?
The EU's safety committee considers it safe in cosmetics at up to 1 per cent. Tolerance varies, so patch test and stop if your skin reacts. Keep it off broken or irritated skin.
Does kojic acid make you sensitive to the sun?
Sun protection is the basic rule for anyone concerned about skin tone, whatever they're using. Our Hyaluronic Acid jar, which has kojic acid, also contains retinol, so wear sunscreen the day after a mask with it.
Can kojic acid remove dark spots?
It's used in products aimed at the look of uneven tone, but results are slow and vary, and a short mask isn't a way to remove a dark spot. Have any new or changing spot checked by a doctor first.
This is general information, not medical advice. If you're worried about your skin, see your GP or a skin specialist.
Sources
- Kojic acid applications in cosmetic and pharmaceutical preparations, Saeedi and colleagues, Biomedicine and Pharmacotherapy, 2019
- Melasma, DermNet
- Opinion on kojic acid, SCCS/1637/21, final version with June 2022 corrigendum, EU Scientific Committee on Consumer Safety
- Skin changes and safety profile of topical products during pregnancy, Putra, Jusuf and Dewi, Journal of Clinical and Aesthetic Dermatology, 2022