Be
Benzoyl Peroxide
Benzoyl Peroxide
Antibacterial workhorse for acne. Kills C. acnes on contact — and bleaches fabrics on contact too.
What it does
Benzoyl peroxide releases free oxygen radicals that kill the bacteria implicated in inflammatory acne. Effective from 2.5% (just as effective as 10% with less irritation). Available OTC. Common in spot treatments and washes.
The evidence, graded
strongOlder tretinoin formulations are partially deactivated by benzoyl peroxide when layered, but newer micro-encapsulated formulations are designed to combine. Some prescriptions intentionally combine them.Martin 1998 · British Journal of Dermatology ↗
expert consensusTopical benzoyl peroxide at 5% or below is generally considered safe across all trimesters of pregnancy and during breastfeeding. Some clinicians still prefer caution — talk to your OB or dermatologist before starting.Bozzo 2011 · Canadian Family Physician ↗
emergingTretinoin is deactivated by benzoyl peroxide when layered in light, and retinol likely shares this susceptibility through a similar oxidation pathway — though direct retinol-plus-BPO stability data is sparse. The conservative move is to use them at different times of day or alternate nights; modern micro-encapsulated formulations are an exception.Martin 1998 · British Journal of Dermatology ↗
Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
Also known as
bpo
Pairs worth knowing
This page is public and indexed on purpose (unlike profiles and drops, which are unlisted) — it’s the citation behind shared ingredient cards, and it should be findable.
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