A brightening active. It inhibits the tyrosinase enzyme and helps even tone in hyperpigmentation. Well tolerated at cosmetic levels.
Topical application
BLimited evidence. One RCT or several controlled studies with limitations.
A tyrosinase-targeting brightening active. Safe at cosmetic levels.
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.
Irritation potential
LowAllergen risk
LowPregnancy
SafeSuitable for
The Evigrade extension adds an evidence panel to iHerb, Sephora, Druni and 12 more stores. This ingredient and every other one in the product show evidence-tier, allergen risk and pregnancy/lactation flags at a glance.
4-Butylresorcinol is considered safe during pregnancy at typical cosmetic concentrations. Systemic absorption through the skin is minimal.
4-Butylresorcinol suits: normal, dry, combination, oily, sensitive.
A brightening active.
The INCI name is 4-Butylresorcinol. It may also appear as: 4-бутилрезорцин, Butylresorcinol, Rucinol.
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