A daily hair wash with C1 immediately provides the hair with the activating ingredient. The Alpecin Caffeine can be detected after being left on for just 120 seconds. If left on for longer, more caffeine will be absorbed into the scalp.Alpecin's product range has been specifically developed to strengthen hair. With its unique galenic formula and its optimal caffeine dosage it helps to counteract the negative effect of testosterone and supports strong hair. The Alpecin Caffeine Complex contains caffeine, zinc and niacinamide for healthy hair roots.Stimulates hair roots during washing, With patented skin activator, Hair energizer, Recharges your hair during washing