Avobenzone vs Padimate O: which is worse?

What is Avobenzone?

Avobenzone (INCI: Butyl Methoxydibenzoylmethane) is a chemical UV filter that is the only FDA-approved broad-spectrum UVA-absorbing active sunscreen ingredient in the US that covers the full UVA spectrum (320–400 nm). It is inherently photounstable and must be combined with photostabilizers.

What is Padimate O?

Padimate O (octyl dimethyl PABA) is an oil-soluble UVB-absorbing UV filter derived from PABA (para-aminobenzoic acid). It was once one of the most common UVB filters in US sunscreens but has declined in use since the 1990s.

Documented risks

Avobenzone: Avobenzone is effective and considered safe at approved concentrations (up to 3% in US OTC sunscreens). A 2019 FDA study found that several sunscreen actives including avobenzone were systemically absorbed above the 0.5 ng/mL threshold after repeated use, triggering a call for additional safety data. This does not indicate harm, but the FDA requested more studies under its proposed sunscreen monograph. Current evidence supports its continued safe use. No clear endocrine disruption or carcinogenicity at human exposure levels is established.

Padimate O: Padimate O is FDA-approved at up to 8%. It is a PABA derivative and carries a rare risk of photoallergic contact dermatitis in individuals sensitive to PABA-related compounds. There are some in vitro studies suggesting potential DNA damage from padimate O under UV exposure, though this has not been substantiated in human studies at cosmetic use levels. The CIR has assessed it as safe. Its use has largely been replaced by more modern, better-tolerated filters.