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
- 8–12 weeks
how it was measured
Measured on melasma clearance, investigator-graded, as an add-on to 2% hydroquinone with 10% glycolic acid; measured at the trial's end, so possibly sooner.PMID 10417583PMID 23918998PMID 40296942
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…
Why we say this
- Kojic 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.
- PMID 36566490 · abstract
- PMID 23918998 · read in full
- PMID 40296942 · abstract
- SCCS/1637/21 (EU Scientific Committee opinion)
- PMID 35642229 · read in full
- PMID 23716817 · abstract
On a label: usually effective at 1-2%.
How much do you need?
Not established
No human trial pins a dose. The reasoning is below, and it is the honest answer.
Why we say this
- Not established as a single agent: the one controlled dose reading is an add-on, 2% kojic acid in a gel of 10% glycolic acid and 2% hydroquinone against the same gel without it, split-face in 40 Chinese women with melasma over 12 weeks, clearing more than half the melasma in 60% versus 47.5% of faces (Lim 1999).
- That 2% sits above the 1% cap the EU set for face products (SCCS/1637/21, Regulation 2022/1181).
- Below 1% nothing controlled exists: 1% alone was one arm of an 80-patient study in which every arm contained kojic acid (Deo 2013).
- A floor the law forbids is not a floor a label can meet.
- PMID 10417583 · abstract
- PMID 23918998 · abstract
- PMID 23716817 · abstract
- PMID 40296942 · abstract
- SCCS/1637/21 (EU Scientific Committee opinion)
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
Give it eight to twelve weeks, and possibly less: that is simply when it was measured.
What was measured, and in whom
- Measured on: melasma clearance, investigator-graded, as an add-on to 2% hydroquinone with 10% glycolic acid.
- The one reading with a control for the ingredient itself: 2% kojic acid added to a gel of 10% glycolic acid and 2% hydroquinone, against the same gel without it, split-face in 40 Chinese women with epidermal melasma, assessed every 4 weeks to week 12; at 12 weeks more than half the melasma had cleared in 60% of kojic sides versus 47.5% of the others, and complete clearance happened only on kojic sides (Lim 1999).
- The abstract reports the 12-week result, so 12 weeks is the trial end, not a demonstrated onset, and the effect is the increment over an active base, not kojic acid alone.
- The 1% arm of Deo 2013 has no non-kojic comparator; the 16-week 2% arm of Patil 2025 has no vehicle.
Light, and how to keep it
Kojic Acid breaks down in light. The packaging is doing real work: opaque, and closed between uses.
how it was measured
While efficacious, KA's inclination to undergo pH-mediated, thermal-, and photodegradation reduces its efficacy, necessitating stabilizing vehicles.PMID 28026947 · abstract
what the source asks of the bottle: opaque, cool
What regulators say
In the EU kojic acid is capped at 1% in face and hand products (Annex III entry 375, Regulation 2024/996: from 1 February 2025 for placing on the market, 1…
What the regulator says, in full
- In the EU kojic acid is capped at 1% in face and hand products (Annex III entry 375, Regulation 2024/996: from 1 February 2025 for placing on the market, 1 November 2025 for sale).
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.
Does Kojic Acid go off?
It breaks down in light, and that is the part that has been measured. While efficacious, KA's inclination to undergo pH-mediated, thermal-, and photodegradation reduces its efficacy, necessitating stabilizing vehicles. So the packaging is not decoration: opaque, and closed between uses. Heat, air and simple age matter too, and we have not sourced numbers for those, so treat this as one reason a product weakens rather than as a shelf life.
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
26 comparisons built, the 2 most looked-up above.
Can you mix Kojic Acid with
3 pairings built, the 1 most looked-up above.
This, for every label you own
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Sources & how we reviewed this
- PMID 36566490abstract read, not the full text
- PMID 23918998read in full
- PMID 40296942abstract read, not the full text
- SCCS/1637/21 (EU Scientific Committee opinion)read in full
- PMID 35642229read in full
- PMID 23716817abstract read, not the full text
What changed on this page
- : the pH it needs
- : the highest dose tested
- : light stability