Widely available OTC bactericidal products containing benzoyl
peroxide may be used in mild to moderate acne. The
gel or cream containing
benzoyl peroxide is rubbed, twice daily, into the pores over the affected region. Bar soaps or washes may also be used and vary from 2 to 10% in strength.
Externally applied antibiotics such as erythromycin, clindamycin, Stievamycin, or tetracycline aim to kill the bacteria that are harbored in the blocked follicles.
ref:http://en.wikipedia.