Skin Care: Benzoyl Peroxide

Benzoyl peroxide oxygenates skin. Acne bacteria cannot live in oxygenated environments. Benzoyl peroxide is also a mild drying and peeling agent which is thought to help keep pores from clogging. 2.5% benzoyl peroxide is just as effective as 5% and 10% but much less irritating. Remember, irritation alone can aggravate acne.

Source
Acne.org