Kojic Acid: Uses, Evidence and Cautions

Q: Can Kojic Acid be combined with other skincare?

It is commonly paired with Sunscreen, niacinamide , vitamin C, arbutin, tranexamic acid , glycolic acid; introduce one new active at a time and stop if irritation develops.

Kojic acid is a fungal-derived tyrosinase inhibitor used in brightening skincare: it binds copper in the enzyme that makes melanin, slowing new pigment in uneven tone, sun spots and post-inflammatory hyperpigmentation. It is a recognised cause of contact dermatitis, so people with sensitive skin should patch test first, and daily sunscreen remains essential.

Key Facts

What it is: A fungal-derived tyrosinase inhibitor used in skincare to reduce uneven pigmentation and dark spots.
Also called: 5-hydroxy-2-hydroxymethyl-4-pyrone; kojic dipalmitate (ester form)
Pairs with: Sunscreen, niacinamide, vitamin C, arbutin, tranexamic acid, glycolic acid
Who should take care: Kojic acid is a recognised cause of contact dermatitis and sensitisation, particularly with long-term use or higher concentrations, so people with sensitive skin or a history of cosmetic allergies should patch test first.
In Singapore: Kojic acid is used in cosmetic brightening products sold in Singapore.

What is kojic acid and what does it do?

Kojic acid is produced by certain fungi during the fermentation of rice, notably in sake and soy sauce production. It inhibits tyrosinase by binding copper at the enzyme's active site, which slows new melanin production. It also has antioxidant activity. In skincare, it is used for uneven tone, sun spots, post-inflammatory hyperpigmentation and as part of melasma combinations, often alongside glycolic acid, hydroquinone alternatives or arbutin. Kojic acid itself can be unstable and darken with air and light, so more stable esters such as kojic dipalmitate are often used, although these may be less potent. Like all brighteners, it slows new pigment rather than removing existing pigment. [1]

Three small glass ampoules of clear and pale-blue solution standing on white marble

“Like all brighteners, it slows new pigment rather than removing existing pigment.”
Dr Sin YongOn topical kojic acid

What does the evidence show?

Reviews describe consistent laboratory evidence for tyrosinase inhibition. Clinical studies, mostly small and often combining kojic acid with other actives, show modest improvement in melasma and hyperpigmentation; few trials test kojic acid alone against placebo. Comparisons with hydroquinone suggest it is generally less potent. It is reasonable as one component of a brightening routine rather than a lead treatment, and long-term tolerability limits continuous use for some people.

Who should avoid kojic acid?

Kojic acid is a recognised cause of contact dermatitis and sensitisation, particularly with long-term use or higher concentrations, so people with sensitive skin or a history of cosmetic allergies should patch test first. Stop if redness, itching or a rash develops. Pregnant or breastfeeding women should discuss use with a doctor.

Is kojic acid available in Singapore?

Kojic acid is used in cosmetic brightening products sold in Singapore. European safety assessors have considered concentrations up to 1% acceptable in face and hand products, and permitted strengths can vary by region. It depends on product and strength, so check with a doctor or pharmacist if a product makes strong lightening claims.

If a dark patch, breakout or irritation is not responding to what you are using, the next step is a diagnosis rather than another product. See the Skin A–Z library for related ingredients.

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Questions Patients Actually Ask

What is Kojic Acid used for?+

A fungal-derived tyrosinase inhibitor used in skincare to reduce uneven pigmentation and dark spots.

Who should avoid Kojic Acid?+

Can Kojic Acid be combined with other skincare?+

It is commonly paired with Sunscreen, niacinamide, vitamin C, arbutin, tranexamic acid, glycolic acid; introduce one new active at a time and stop if irritation develops.

How do I patch test kojic acid?+

Apply a small amount to a discreet area, such as the inner forearm, and watch for redness, itching or swelling before using it on the face. Kojic acid is a recognised cause of contact dermatitis, so stop using it and see a doctor if a reaction develops.

Is kojic acid suitable for long-term use?+

Sensitisation is more likely with long-term use or higher concentrations, so use it as directed and stop if irritation appears. Daily sunscreen remains essential. If pigment is persistent or changing, see a doctor rather than increasing the strength or frequency.

Medically reviewed by Dr Sin Yong, MBBS (NUS), MRCS (Edinburgh) · Last updated 7 October 2026 · Editorial policy

Availability in Singapore

Kojic acid is a cosmetic ingredient in Singapore. Products containing it are notified to the HSA under the Health Products Act and must meet the ASEAN Cosmetic Directive annexes, which at present list no specific concentration restriction for kojic acid; typical products contain 1–2%. It is a known contact sensitiser, so patch testing is sensible. Imported 'kojic soap' sometimes contains undeclared hydroquinone or mercury, which the HSA has flagged. A doctor assesses the pigmentation type before recommending kojic acid or a prescription alternative. Source.