Ingredient glossary
Thiamidol
On your shelf ✓What Thiamidol does for your skin, who it suits, and what to watch for.
INCI: Isobutylamido Thiazolyl Resorcinol
In short: Thiamidol delivers brightening and antioxidant, suits most skin types, and the evidence behind it is strong. One thing to know: clear it with your doctor if pregnant; introduce it gently.
- What it does
- Brightening, antioxidant
- Best for
- Most skin types
- Watch out
- Clear it with your doctor if pregnant; introduce it gently
- Evidence
- Strong
- How long
- 2–4 weeks
The molecule
The Glow take
One of the ingredients I trust most.
When your goal is fading dark spots and evening out tone, Thiamidol delivers, and the research properly backs it up. Introduce it gently, and pair it with something soothing if your skin runs sensitive.
— Maya
What it does
- brightening
- antioxidant
strong evidenceA twenty four week randomized double blind study showed daily thiamidol-containing serum and care products produced significant MASI reductions and melasma improvement versus vehicle with sustained benefit after treatment.
On a label: usually effective at 0.1-0.3%.
Who it's for, and who should skip it
Tends to suit
- pigmentation
- melasma
- postinflammatory hyperpigmentation
- normal
- combo
- oily
Approach with care
- very sensitive
- compromised barrier
- pregnancy
- Clogs poresLow
- Irritation riskModerate
How it fits each skin type
- DrySuits
- CombinationSuits
- OilySuits
- SensitiveTake care
Often chosen for pigmentation, melasma, postinflammatory hyperpigmentation. Take extra care if any of these apply to you: compromised barrier, pregnancy.
Where it fits in your routine
Give it two to four weeks — that is when the change first became measurable.
What was measured, and in whom
Measured on: modified MASI facial pigment score, blinded physician assessment of standardised photographs against vehicle.
The first large vehicle-controlled trial randomised 200 people with facial hyperpigmentation to 0.2% thiamidol cream or vehicle for 12 weeks, with blinded physician mMASI at weeks 4, 8 and 12. Thiamidol beat vehicle at every visit, including the earliest: 11.8% versus 5.4% reduction from baseline at week 4, 27.9% versus 13.6% at week 8, 36.1% versus 16.1% at week 12, all P<0.001. Week 4 is the first assessment there was, so onset could be earlier still - a suction-blister and acne PIH study reports vehicle-controlled separation at 2 weeks - but four weeks is the earliest point anyone has measured and shown against a control in facial pigment. The concentration is the one in the marketed serum, which is unusual. Four caveats stay attached. Improvement keeps accumulating to week 12 and beyond, so the first significant visit is not the best result. In the same trial patient global assessments and digital colour analysis found no difference between groups, and there was no effect on freckles or solar lentigines - it is the physician score on melasma-type pigment that moved. The study was Beiersdorf-funded with a Beiersdorf co-author, though run at an independent centre and prospectively registered. And the older 12-week split-face study against 4% hydroquinone, still the most-cited thiamidol paper, has no vehicle arm and cannot date anything.
PMID:41566113 - Lekhavat C, Rojanamatin J, Suphannaphong M, Kolbe L. Efficacy and tolerability of 0.2% thiamidol cream for facial hyperpigmentation: a randomized, double-blind, and vehicle-controlled study. Dermatol Ther (Heidelb) 2026;16(3):1551-1565 (NCT03926845) - the week-4 vehicle separation. PMID:30825454 - Arrowitz C, Schoelermann AM, Mann T, Jiang LI, Weber T, Kolbe L. Effective tyrosinase inhibition by thiamidol results in significant improvement of mild to moderate melasma. J Invest Dermatol 2019;139(8):1691-1698.e6 - the 12-week hydroquinone comparison, active-comparator only.
Plays well with
- sunscreens
- vitamin c
- niacinamide
Thiamidol, answered
Is Thiamidol safe during pregnancy?
Clear it with your doctor first. Thiamidol is flagged as use-with-caution during pregnancy and breastfeeding, so check with your doctor or midwife before adding it.
Who should avoid Thiamidol?
Approach Thiamidol with care if any of these apply to you: very sensitive, compromised barrier, and pregnancy. Its irritation risk is moderate, so introduce it slowly and patch test first.
What concentration of Thiamidol actually works?
Thiamidol tends to do its job in the 0.1 to 0.3% range. Much lower and it is likely underdosed.
During pregnancy
Treat Thiamidol 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 →
Compare Thiamidol with
- Niacinamide
- Vitamin C (LAA)
- Retinal
- Hydroxypinacolone Retinoate
- Retinyl Retinoate
- Azelaic Acid
- Tranexamic Acid
- Kojic Acid
- Phytic Acid
- THD Ascorbate
- Sodium Ascorbyl Phosphate
- Magnesium Ascorbyl Phosphate
- Ascorbyl Glucoside
- Ethyl Ascorbic Acid
- GHK-Cu
- Bakuchiol
- Alpha Arbutin
- Caffeine
- Hydroquinone
- Galactomyces Ferment Filtrate
- Rice Extract
- Cysteamine
- N-Acetyl Glucosamine
- Tetrahydrocurcumin
- Exosomes
- Epidermal Growth Factor
- Carnosine
- 4-n-Butylresorcinol
- 4-Hexylresorcinol
Can you mix Thiamidol with
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