Ingredient glossary

Thiamidol

What Thiamidol does for your skin, who it suits, and what to watch for.

INCI: Isobutylamido Thiazolyl Resorcinol

Worth paying for

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
Does it clash with what you use? Check it →

The molecule

Tap to enlarge
Chemical structure of Thiamidol (Isobutylamido Thiazolyl Resorcinol)

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

WhenMorning or evening
Where in the orderAfter cleansing, before your moisturizer

Plays well with

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.

This, for every label you own

One ingredient is easy. A full label is where it gets confusing. The Ingredient Decoder reads any product and tells you the honest truth, ingredient by ingredient.

Decode my products →

Sources & how we reviewed this

Last reviewed July 2026. Educational information about a cosmetic ingredient, not medical advice.