Benzoyl peroxide, still — the case for resistance-neutral acne care

Acne vulgaris is an inflammatory disease of the pilosebaceous unit, driven by excess sebum, follicular hyperkeratinisation, the commensal bacterium Cutibacterium acnes, and the inflammation these provoke. For decades, antibiotics were a first reflex. That reflex created a problem now impossible to ignore: antibiotic resistance.

The resistance debt

Widespread, prolonged use of topical antibiotics — often as monotherapy — selected for resistant strains of C. acnes and contributed to the broader burden of antimicrobial resistance. The result is that some antibiotic-based regimens are simply less effective than they were a generation ago, and that dermatology has a duty to use antibiotics sparingly and never alone.

Why benzoyl peroxide is different

Benzoyl peroxide kills C. acnes by a fundamentally different mechanism: it releases reactive oxygen species that oxidise bacterial proteins non-specifically. Because the attack is chemical and multi-target rather than a single enzyme interaction, bacteria do not develop resistance to it — a property that has held true across decades of use. It also has mild comedolytic action, helping clear the follicular plugging that starts a lesion.

The modern role

Current guidance places benzoyl peroxide at the centre of mild-to-moderate acne care — used alone for milder disease and, crucially, combined with topical retinoids or antibiotics where those are indicated, because it suppresses the emergence of resistance in the companion drug. The trade-offs are modest: transient dryness and the well-known tendency to bleach fabric. Improvement is visible by around four weeks and optimal at eight to twelve. It is inexpensive, off-patent and unglamorous — and, on the evidence, one of the most sensible things we can still put on inflamed skin.