Alpecin Double Effect Shampoo with caffeine complex against dandruff & hair loss. Stage One: The Double Effect Shampoo loosens scaly, keratinous cells and helps remove dandruff from the scalp. Stage Two: With the scalp cleared of dandruff, the caffeine complex can penetrate into the hair root and help strengthen it against hair loss. Recommendation: massage into the scalp and leave for 2 minutes - from application to rinse. Information for competitive athletes: Alpecin caffeine can be detected in hair follicles.