After washing with a mild cleanser and water, apply ACNECIDE 5 once or twice a day to the entire affected areas, or as directed by your doctor or pharmacist. Read more at http://www.boots.com/en/Acnecide-5-w-w-Gel-30g_1677168/#GwWCGzUsfIHxarDx.99 Acnecide contains the active substance benzoyl peroxide which attacks the bacteria (germs) known as Propionibacterium acnes, one of the main causes of acne. Your doctor or pharmacist has recommended this medicine to treat your acne. Acne appears as blackheads and whiteheads which people often refer to as pimples or spots. Acne of the face, chest or back may be treated with this medicine.