4-Butylresorcinol
A brightening active. It inhibits the tyrosinase enzyme and helps even tone in hyperpigmentation. Well tolerated at cosmetic levels.
Evidence by route
Topical application
A tyrosinase-targeting brightening active. Safe at cosmetic levels.
- CIR Cosmetic Ingredient Review safety assessment
How to read tiers A–F
- BLimited evidence. One RCT or several controlled studies with limitations
Tolerability and safety
- Irritation potential
- Low
- Allergen risk
- Low
- Pregnancy
- Safe
- Suitable for
- Normal, Dry, Combination, Oily, Sensitive
About this ingredient
4-Butylresorcinol (rucinol) is a synthetic brightening active. INCI: 4-Butylresorcinol. In a formula it works against hyperpigmentation: it is one of the strongest tyrosinase inhibitors among cosmetic brighteners, suppressing the key enzyme of melanin synthesis. Unlike many plant brighteners, 4-butylresorcinol has clinical work on reducing dark spots and melasma, so it counts as a working brightening active. The effect builds gradually and needs regular use and daytime sun protection. Pregnancy safety. Topical use, low systemic absorption, but active brighteners are usually postponed in pregnancy because pigmentation often fades on its own after birth. The decision is best made with a doctor. Tolerance. Irritation potential is low, with occasional mild irritation possible at the start.
Frequently asked questions
Is 4-Butylresorcinol safe during pregnancy?
4-Butylresorcinol is considered safe during pregnancy at typical cosmetic concentrations. Systemic absorption through the skin is minimal.
What skin types is 4-Butylresorcinol for?
4-Butylresorcinol suits: normal, dry, combination, oily, sensitive.
What is 4-Butylresorcinol and what does it do in cosmetics?
A brightening active.
What's the INCI name for 4-Butylresorcinol?
The INCI name is 4-Butylresorcinol. It may also appear as: Butylresorcinol, Rucinol.
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