Benzoyl peroxide and salicylic acid are both recommended topical treatments for the management of acne, but differ in the manner in which they work. Bacteria (P. acnes) on the skin are key factor involved in the development of acne lesions, so reducing the number of bacteria on the skin can help reduce inflammation and clogging of the pores.
Benzoyl peroxide helps to improve acne through two different effects. It is a potent antimicrobial agent that acts on the surface of the skin and in the follicles which become blocked and inflamed, resulting in the development of acne lesions. One advantage of benzoyl peroxide is that it is uncommon for bacteria to become resistant to it, so benzoyl peroxide is effective on an ongoing basis. In addition to its antibacterial effect, benzoyl peroxide also helps to exfoliate the skin and prevent the pores from clogging.
Salicylic acid improves acne by promoting the shedding of the outermost layer of the skin, which helps to unclog pores. It does not have any effect on bacteria or the production of sebum. Thus, while benzoyl peroxide and salicylic acid both promote shedding or removal of the outer layer of the skin to help unclog pores, benzoyl peroxide has the additional benefit of an antibacterial effect.