Acnestar soap is a deep cleansing bar contains benzoyl peroxide 2.5%. Benzoyl peroxide treats acne in three ways: by killing bacteria, peeling away dead skin cells and drying excess skin oil. Benzoyl peroxide is most effective in getting rid of the dirt accumulated to clear up the pores. Benzoyl peroxide works as a peeling agent. It increases skin turnover, clearing pores and reducing the bacterial count (specifically acnes) as well as acting directly as an antimicrobial.