Hi. Both Benzoyl peroxide and Retinoic Acid are good molecules for Acne. While Retinoic Acid derivatives have to be only applied at night over the affected lesions for 30 mins to 1 hour,Benzoyl peroxide (2.5,4,5%) can be applied during the day over the acne lesions for 30 mins to 1 hour.Both may cause stinging,irritation or dryness but if used carefully, they their benefits outweigh the side effects. Regards, Dr.Sanchit Talwar, MD (Skin & VD), Consultant Dermatologist, Dr Talwar's Skin, Laser and Cosmetic Clinic CHANDIGARH.