4-n-Butylresorcinol

What is it?

A tyrosinase-inhibiting brightening active used in serums and spot-treatment products targeting hyperpigmentation, dark spots and uneven tone.

What does it do?

According to PubMed, a multicenter, single-blind clinical study found 4-n-butylresorcinol to be by far the most potent inhibitor of human tyrosinase among the compounds tested (IC50 of 21 umol/L), far exceeding hydroquinone, arbutin and kojic acid, and confirmed in vivo that it visibly reduced age spots within 8 weeks versus a vehicle control; a second comparison in the same study also found it more effective than both 4-hexylresorcinol and 4-phenylethylresorcinol (DOI: https://doi.org/10.1111/jdv.12051). A 2026 formulation study explored co-delivering 4-butylresorcinol with licochalcone A specifically to offset its known skin irritancy while preserving its whitening effect, reporting a 30.55% reduction in skin melanin content after 28 days of use (DOI: https://doi.org/10.1039/d5tb01755f).

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