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Ingredient glossary

4-n-Butylresorcinol

What 4-n-Butylresorcinol does for your skin, who it suits, and what to watch for.

INCI: 4-Butylresorcinol · Also: Rucinol

Solid and proven

In short: 4-n-Butylresorcinol 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
4–8 weeks
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Written by Maya FaourHow we score →

The molecule

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The Glow take

One of the ingredients I trust most.

When your goal is fading dark spots and evening out tone, 4-n-Butylresorcinol 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 evidenceHuman tyrosinase, skin model, and small controlled human studies support pigment reduction. Evidence is good for hyperpigmentation, but the clinical base is still smaller than for older drugs.

On a label: usually effective at 0.1-1%.

Who it's for, and who should skip it

Tends to suit

  • pigmentation
  • melasma
  • photoaged

Approach with care

  • very sensitive
  • pregnancy
  • Clogs poresLow
  • Irritation riskModerate

How it fits each skin type

  • DryNeutral
  • CombinationNeutral
  • OilyNeutral
  • SensitiveTake care

Often chosen for pigmentation, melasma, photoaged. Take extra care if any of these apply to you: pregnancy.

Where it fits in your routine

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

Give it four to eight weeks, and possibly less: that is simply when it was measured.

What was measured, and in whom

Measured on: visible reduction in age spots.

In an age spot study on the forearm, subjects treated two spots twice daily with a 4-n-butylresorcinol formula and two spots with the matching vehicle. Within 8 weeks the treated spots showed a visibly reduced age spot appearance while the vehicle spots showed none. The abstract gives no participant count, no concentration and no statistics. A second study in the same paper found 4-butylresorcinol more effective than 4-hexylresorcinol and 4-phenylethylresorcinol, and reports nothing else about it.

PMID:23205541(full)

Plays well with

4-n-Butylresorcinol, answered

Is 4-n-Butylresorcinol safe during pregnancy?

Clear it with your doctor first. 4-n-Butylresorcinol is flagged as use-with-caution during pregnancy and breastfeeding, so check with your doctor or midwife before adding it.

Who should avoid 4-n-Butylresorcinol?

Approach 4-n-Butylresorcinol with care if any of these apply to you: very sensitive and pregnancy. Its irritation risk is moderate, so introduce it slowly and patch test first.

What concentration of 4-n-Butylresorcinol actually works?

4-n-Butylresorcinol tends to do its job in the 0.1 to 1% range. Much lower and it is likely underdosed.

During pregnancy

Treat 4-n-Butylresorcinol 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 4-n-Butylresorcinol with

Can you mix 4-n-Butylresorcinol with

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Sources & how we reviewed this

  1. PMID 23205541read in full
  2. PMID 16327152abstract only, the full text is paywalled
  3. PMID 27666581abstract only, the full text is paywalled

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