Alpecin Caffeine Shampoo C1 Achieve great things with this Caffeine Shampoo C1 from Aplecin. A natural stimulant caffeine penetrates into hair to work directly into follicles to improve structure and stimulate growth. Leave on for 2 minutes to allow for full penetration. If left on for longer the caffeine continues to work into the scalp leaving you with a more intense treatment. Fine weakened hair becomes stronger and easier to style. Directions of use: Distribute shampoo evenly into your hands. Massage into your wet hair. Rinse thoroughly. Repeat if necessary.