Kills the Propionibacterium acnes bacteria that infects blackheads and whiteheads and turns them into pimples. Perrigo Benzoyl Peroxide 2.5 Percent Hydroalcoholic Base Acne Gel For Acne Treatment Indicated for use in the topical treatment of mild to moderate acne vulgaris. Benzoyl Peroxide Gel 2.5% may be used as an adjunct in acne treatment regimens including antibiotics, retinoic acid products, and sulfur/salicylic acid containing preparations. Clinical Pharmacology The exact method of action of benzoyl peroxide in acne vulgaris is not known. Benzoyl peroxide is an antibacterial agent with demonstrated activity against Propionibacterium acnes. This action, combined with the mild keratolytic effect of benzoyl peroxide is believed to be responsible for its usefulness in acne. Benzoyl peroxide is absorbed by the skin where it is metabolized to benzoic acid and excreted as benzoate in the urine. Benzoyl peroxide is known to dermatologists as the gold standard of topical acne treatments. When applied to your acne prone skin, hether as a pimples cream, gel or lotion, it breaks down into hydrogen peroxide and benzoic acid. It is the hydrogen peroxide that is believed to be active in fighting acne. Benzoyl peroxide kills the P.acnes bacteria that infects blackheads and whiteheads and turns them into pimples. One advantage over other antibiotics is that bacteria don't develop a 'resistance' to benzoyl peroxide. It also might have some effect in clearing blocked pores.