Ingredient glossary
Kojic Acid
On your shelf ✓What Kojic Acid does for your skin, who it suits, and what to watch for.
INCI: Kojic Acid
In short: Kojic Acid delivers brightening, earns its place for pigmentation and melasma, and the evidence behind it is moderate. One thing to know: clear it with your doctor if pregnant; introduce it gently.
- What it does
- Brightening
- Best for
- Pigmentation, melasma
- Watch out
- Clear it with your doctor if pregnant; introduce it gently
- Evidence
- Moderate
- How long
- Never measured
The molecule
The Glow take
One of the ingredients I trust most.
When your goal is fading dark spots and evening out tone, Kojic Acid delivers, with a solid amount of evidence behind it. Introduce it gently, and pair it with something soothing if your skin runs sensitive.
— Maya
What it does
- brightening
moderate evidenceKojic acid does lighten pigment, but it is the mildest of the mainstream options: a meta-analysis of 45 melasma trials placed it last among the agents it called comparable. The clearest single-ingredient result used 1% — randomised, 12 weeks, 20 people, though with no placebo arm — and reported a 59% mean MASI improvement. Above 1% the evidence thins out to one open-label, manufacturer-sponsored trial, and regulators have settled on 1% anyway: the EU's safety committee judged that the ceiling and EU law now limits face and hand products to it, so 1% is the level to look for. The reaction to watch is allergic contact dermatitis, which tends to appear after weeks or months of use rather than scaling with the percentage.
On a label: usually effective at 1-2%.
Who it's for, and who should skip it
Tends to suit
- pigmentation
- melasma
- post inflammatory hyperpigmentation
Approach with care
- very sensitive
- compromised barrier
- Clogs poresLow
- Irritation riskModerate
How it fits each skin type
- DryNeutral
- CombinationNeutral
- OilyNeutral
- SensitiveTake care
Often chosen for pigmentation, melasma, post inflammatory hyperpigmentation. Take extra care if any of these apply to you: compromised barrier.
Where it fits in your routine
Nobody has published how long this takes to work.
What is known, and what is missing
Measured on: melasma pigment score (MASI) — the brightening job this row is sold on.
The 12-week anchor does not survive reading: it is one arm of an 80-patient four-group study in which every group received kojic acid 1% — alone, with 2% hydroquinone, with 0.1% betamethasone valerate, or with all three — so there is no non-kojic arm anywhere in it, and all patients were additionally put on strict photoprotection and daily SPF 15. Melasma pigment falls substantially on sunscreen alone, so the 58.72% MASI improvement in the kojic-alone group of 20 cannot be attributed to the ingredient, let alone timed; MASI was scored at baseline, week 4 and week 12, but with nothing to compare against an interim visit buys nothing. The rest of the file is no stronger: the remaining human work is active-comparator or open-label without a vehicle — one alternate-allocation comparison in which the kojic arm was actually 0.75% kojic acid plus 2.5% vitamin C, and one industry-run open-label 16-week study in which 2% kojic acid moved mMASI by only 10%, an order of magnitude below the 58.72% figure — and the remainder are systematic reviews, which cannot establish an onset. Allergic contact dermatitis appears after weeks to months, which is a separate clock from efficacy. EU law caps face and hand products at 1% in any case.
Deo KS, Dash KN, Sharma YK, Virmani NC, Oberai C. Kojic Acid vis-a-vis its Combinations with Hydroquinone and Betamethasone Valerate in Melasma: A Randomized, Single Blind, Comparative Study of Efficacy and Safety. Indian J Dermatol 2013;58(4):281-5. PMID:23918998 — all four arms received kojic acid, no vehicle, universal SPF 15. Also read: Monteiro RC et al. Indian J Dermatol 2013;58(2):157. PMID:23716817; Patil R et al. Cureus 2025;17(3):e81330. PMID:40296942; Chang YF et al. J Cosmet Dermatol 2023;22(4):1168-1176. PMID:36566490 (systematic review); SCCS/1637/21. No vehicle-controlled trial of topical kojic acid located.
Plays well with
- arbutin
- vitamin c
- niacinamide
Kojic Acid, answered
Is Kojic Acid safe during pregnancy?
Clear it with your doctor first. Kojic Acid is flagged as use-with-caution during pregnancy and breastfeeding, so check with your doctor or midwife before adding it.
Who should avoid Kojic Acid?
Approach Kojic Acid with care if any of these apply to you: very sensitive and compromised barrier. Its irritation risk is moderate, so introduce it slowly and patch test first.
What concentration of Kojic Acid actually works?
Kojic Acid tends to do its job in the 1 to 2% range. Much lower and it is likely underdosed.
During pregnancy
Treat Kojic Acid as a maybe rather than a yes for now. It is flagged as one to use with caution while pregnant or breastfeeding, so it is worth clearing before you carry on.
When in doubt, check with your doctor or midwife. They outrank any website, including this one.When it is worth booking →
Commonly confused with
- Alpha ArbutinBoth fade dark spots by slowing pigment. Arbutin is the gentle everyday option; kojic is stronger but more likely to irritate.
Compare Kojic Acid with
- Niacinamide
- Vitamin C (LAA)
- Retinal
- Hydroxypinacolone Retinoate
- Retinyl Retinoate
- Azelaic Acid
- Tranexamic Acid
- Phytic Acid
- THD Ascorbate
- Sodium Ascorbyl Phosphate
- Magnesium Ascorbyl Phosphate
- Ascorbyl Glucoside
- Ethyl Ascorbic Acid
- Bakuchiol
- Alpha Arbutin
- Hydroquinone
- Galactomyces Ferment Filtrate
- Rice Extract
- Thiamidol
- Cysteamine
- N-Acetyl Glucosamine
- Tetrahydrocurcumin
- Exosomes
- Epidermal Growth Factor
- 4-n-Butylresorcinol
- 4-Hexylresorcinol
Can you mix Kojic Acid with
This, for every label you own
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Sources & how we reviewed this
- PMID 36566490abstract only, the full text is paywalled
- PMID 23918998read in full
- PMID 40296942abstract only, the full text is paywalled
- SCCS/1637/21 (EU Scientific Committee opinion)read in full
- PMID 35642229read in full
- PMID 23716817abstract only, the full text is paywalled