Alpecin Coffein Shampoo C1 has a caffeine-enhanced formula that strengthens weak hair roots, promotes hair growth, and counteracts premature hair loss. Caffeine has been shown to promote hair growth, and this shampoo immediately provides the hair roots with the active ingredients that help stimulate and increase growth. The process becomes apparent when it is left on and absorbed by the hair follicles for as little as 2 minutes. Left on even longer, the stimulating caffeine will even be absorbed into the scalp. Alpecin Coffein Shampoo C1- the Hair Energizer!