Duac Gel contains clindamycin and benzoyl peroxide, which work together to reduce acne-causing bacteria, unblock pores and calm skin inflammation. Apply a thin layer once daily exactly as prescribed, avoiding the eyes and lips. Common side effects include dryness, redness, peeling and mild skin irritation. Duac may bleach fabrics and hair, so wash your hands after application and avoid contact with clothing or bedding until dry.