What it is
PABA was one of the first widely used organic UVB filters. It absorbs UVB but not UVA, and it has largely fallen out of use because it can stain fabric and is a relatively common cause of allergic skin reactions. Modern sunscreens almost always use newer, better-tolerated filters instead.
Spectrum coverage
UVB
Regional approval · max %
Safety & warnings
PABA is a recognized contact and photoallergen for some people and can stain clothing, which is why it is seldom used today; PABA-free is a common formulating choice.
Origin & sourcing
Synthetic organic compound (PABA also occurs naturally as a B-vitamin-related substance).
History
PABA was among the earliest sunscreen actives, popular in mid-20th-century products before being displaced by less sensitizing filters.
Questions everyone asks
Why is PABA rarely used now?
It can cause allergic reactions and stain fabric, so it has been replaced by newer, gentler UVB filters.
What UV range does PABA cover?
It absorbs UVB only, so it would need separate UVA filters for broad-spectrum protection.