Benzoyl peroxide kills acne-causing bacteria, and salicylic acid exfoliates the skin to remove dead skin cells that can blog pores, according to the American Academy of Dermatology. Benzoyl peroxide is very effective for occasional treatment and salicylic acid is often recommended for daily use. The two ingredients often come in washes, creams and cleansing cloths.
Benzoyl peroxide comes in varying concentrations from 2.5 percent and above, although higher concentrations aren't necessarily more effective at controlling acne and can cause skin reactions, according to the American Academy of Dermatology. This ingredient is very fast-acting and can reduce an acne outbreak in as few as five days, notes HowStuffWorks.
Dermatologists sometimes advise benzoyl peroxide for use in conjunction with certain prescription acne medications, notes the American Academy of Dermatology. For example, when used with topical clindamycin the two ingredients kill bacteria and prevent it from growing. Individuals can also pair benzoyl peroxide with salicylic acid, however this sometimes causes dryness and irritation of the skin.
In addition to exfoliating, salicylic acid helps to reduce inflammation, notes Teen Vogue. It dissolves the hardened oils that holds cells together and clog pores. This exfoliation can cause short-term irritation in some people while the skin adjusts the acidic qualities of the ingredient.
Salicylic acid is effective for dermatological conditions such as psoriasis because the salicylic acid softens and removes the outermost layer of skin, including scales, notes HowStuffWorks.