How much thiamidol do you need? 0.2%+
The effective thiamidol percentage, by the vehicle-controlled trials, starts at 0.2%; no published dose comparison sets a ceiling.
Give it two to four weeks: that is when the change first became measurable.
how it was measured
Measured on modified MASI facial pigment score, blinded physician assessment of standardised photographs against vehicle; the first visit at which the change was measurable.PMID 41566113PMID 30825454
What thiamidol percentage is effective?
Every trial uses 0.2%.
0.2%+
The trials, and what they used
- 0.2% thiamidol cream beat vehicle cream on mMASI at weeks 4, 8 and 12 in 200 randomised adults of both sexes, 36.1% against 16.1% reduction at week 12 with no significant adverse events (Lekhavat 2026, double-blind, Beiersdorf co-authored); 0.2% twice daily matched 4% hydroquinone at bedtime in 50 women with melasma over 90 days, 43% against 33% mMASI reduction, with contact allergy in 2 of 25 (Lima 2021, independent); a thiamidol formulation lightened suction-blister hyperpigmentation against vehicle within 2 weeks and acne marks over 12 weeks (Roggenkamp 2021).
- No dose comparison found: no other concentration has been tested in people, so 0.2% is the floor and the only measured level, not a ceiling.
Is more than 0.2% thiamidol better?
Nobody has measured it: no published dose comparison sets a ceiling for thiamidol, so a percentage above 0.2% is above the trials' floor, not above a measured maximum. Only one strength has ever been tested, 0.2% (Lima 2021), and the paper reports contact allergy there.
There were only mild adverse effects in the Thiamidol group, but allergic contact dermatitis was evidenced in two (8%) participants.
The highest dose tested, in the paper’s words
- There were only mild adverse effects in the Thiamidol group, but allergic contact dermatitis was evidenced in two (8%) participants.
No published dose comparison sets a ceiling for thiamidol. A declared percentage above 0.2% is above the trials' floor, not above a measured maximum: the trials say from 0.2% it works, and say nothing about whether more does more.
What does the thiamidol percentage on a label tell you?
A name that states a percentage ("Thiamidol 0.2%") is the only amount a cosmetic label ever declares, so it is the one number that can be read against the trials: at or above the 0.2% floor, or below it.
A name without a percentage leaves the position. The rules make a brand list ingredients in descending order of amount down to 1%, and in any order below it, so thiamidol above the 1% line is at least 1% and thiamidol below it can be any trace the brand likes. The floor the trials worked from is 0.2%, and a position alone cannot tell you whether a label reaches it.
The thiamidol percentages in our catalogue
One label carries it without a number, so the position is all there is:
- Eucerin Anti-Pigment Dual SerumThiamidol sits 11th of 30, above the 1% line; the label does not say how much, and the trials worked from 0.2%.
Read on
- Thiamidol: the glossary page what it does, who it suits, where it fits
- Thiamidol vs Niacinamide
- Thiamidol vs Vitamin C (LAA)
- Thiamidol vs Retinal
- Thiamidol vs Hydroxypinacolone Retinoate
- Thiamidol vs Retinyl Retinoate
- Thiamidol vs Azelaic Acid
Other actives with a dose the trials pinned:
- Niacinamide 2%+
- Vitamin C (LAA) 5%+
- Retinol 0.075 to 0.3%
- Salicylic acid (BHA) 0.5%+
- Lactic acid 8%+
- Glycolic acid 5%+
- Retinal 0.05 to 0.1%
- Retinyl Retinoate 0.06%+
- Tretinoin 0.025%+
- Adapalene 0.1%+
- Tazarotene 0.045%+
- Azelaic Acid 15%+
- THD Ascorbate 1%+
- Sodium Ascorbyl Phosphate 5%+
- Palmitoyl Pentapeptide-4 0.0003%+
- Caffeine 2%+
- Benzoyl Peroxide 2.5 to 5%
- Tea Tree Oil 5%+
- Hydroquinone 4%+
- Bifida Ferment Lysate 10%+
- Cysteamine 5%+
- Menthol 0.1 to 5%
- Peppermint Oil 0.5%+
- N-Acetyl Glucosamine 2%+
- Alpha Lipoic Acid 5%+
- Ammonium lactate 12%+
- Acetylated Hyaluronic Acid 0.1%+
- 4-n-Butylresorcinol 0.1%+
- 4-t-Butylcyclohexanol 0.4%+
- Sphingomonas Ferment Extract 2%+