Bumetrizole

Bumetrizole is an oil-soluble UV filter/photostabilizer used in sunscreens at low-to-moderate concentrations, and available data generally show low rates of irritation and sensitization in standard patch testing. However, as a chemical UV filter it is not completely inert—stinging or dermatitis can occur in highly reactive or eczematous skin, especially with compromised barriers and leave-on exposure. For patient-safety prioritization in sensitive populations, this fits a "gentle" but not "very gentle" irritancy profile. Safety Notes: Bumetrizole (UV filter/photostabilizer; commonly listed as Bumetrizole or Butyl Methoxydibenzoylmethane stabilizer in some markets) is observed in commercial leave-on sunscreens and day creams at low levels around ~0.1–1% when used primarily as a stabilizer/auxiliary UV absorber. High-strength consumer sunscreens, particularly in markets allowing higher UV-filter loads, have been marketed with bumetrizole in the mid-to-high single digits, with up to ~10% appearing in some OTC leave-on sunscreen formulations; it is uncommon in rinse-off products.