Alpecin Caffeine Shampoo (250ml). The shampoo that stimulates hair growth directly at the roots.. stimulates hair growth directly at the roots. weakened hair becomes stronger. by intentionally leaving out conditioning agents your hair is immediately provided with more grip. The shampoo which deliberately avoids silicones.. Since no softeners are used (e.g. silicone), the structure of the hair improves and your hair will have enhanced grip after just a few washes. Fine and weakened hair becomes stronger and easier to style.