Damages the bacterial cell membrane directly rather than inhibiting an enzyme or a receptor
Benzoyl peroxide releases free radicals that oxidize C. acnes membrane lipids; chlorhexidine is a cation that disrupts the membrane and precipitates cytoplasm
Physicochemical action, so resistance is rare — but selectivity is poor, which is why both are topical only
Drugs with this mechanism (2)
Benzoyl peroxide — Topical antibacterial oxidant for acne; irritates skin and bleaches fabric.
Chlorhexidine — Broad topical antiseptic for skin and oral decontamination; persists on tissue.