Why double effect? Hair loss and dandruff are the two most frequent scalp problems which affect men. Dr. Wolff Research has developed a shampoo that simultaneously helps to counteract both problems: Alpecin Double-Effect Caffeine Shampoo. 1st effect: In the first step, this Double-Effect Caffeine Shampoo loosens scaly, keratinous cells and thoroughly removes dandruff from the scalp. From a dermatological standpoint, the combination of the two effective anti-dandruff substances, salicylic acid and octopirox, is recommendable because it takes into account all dermatologically relevant aspects of cosmetic dandruff: Gentle dandruff removal Supports natural resistance of the scalp Antimicrobial properties 2nd effect: The removal of dandruff from the scalp has prepared the way for the caffeine complex. Alpecin Double-Effect Caffeine Shampoo contains caffeine that stimulates the hair already during hair washing. It can be detected after just 120 seconds of residence time. In the hair, the active ingredient forms a 24-hour depot.