4-Butylresorcinol
Description
1,3-Dihydroxy-4-N Butyl Benzene
Function
Properties
Regulatory Status
CAS 18979-61-8 (EC 242-036-1). EU: Present in CosIng database; restricted under Annex III of Regulation EC 1223/2009 for skin-lightening use with concentration limits. No dedicated SCCS safety opinion issued. US: Not prohibited or restricted by FDA; freely permitted as cosmetic ingredient. Japan: Approved as quasi-drug active ingredient for skin lightening since 1999. Most potent tyrosinase inhibitor known (IC50 21 umol/L).
Not restricted or prohibited by the US FDA for use in cosmetic products. No dedicated CIR safety assessment published as of 2025. EWG Skin Deep database rates low hazard. Freely used in US OTC cosmetic products without concentration restrictions. Not classified as a drug active ingredient by FDA.