Benzoyl Peroxide
Also known as: BPO, Benzoyl Peroxide 2.5%, Benzoyl Peroxide 5%, Benzoyl Peroxide 10%
The gold standard for inflammatory acne — and the one active that actually kills bacteria on contact rather than just calming the aftermath.
What It Does
Deep Dive
Benzoyl peroxide works by releasing oxygen into the pore, which C. acnes (the bacteria behind most inflammatory breakouts) cannot survive. Unlike antibiotics, bacteria cannot build resistance to it — which is why dermatologists often pair it with antibiotic or retinoid therapy to prevent resistance. Landmark trials (including a 2002 BMJ head-to-head) showed that 2.5% BPO is as effective as 5% or 10% for acne reduction, with dramatically less irritation. Bleaches fabric on contact, so use white towels and pillowcases. Pregnancy safety is category C — limited data but widely considered acceptable in small amounts by most dermatologists. Can cause contact dermatitis in the first 1-2 weeks; introduce slowly and pair with a barrier-friendly moisturizer.
Health & Safety
Pregnancy Safety