Alpecin caffeine shampoos, such as Alpecin Coffein Shampoo and Alpecin C1 Caffeine Shampoo, contain caffeine as a key ingredient. Caffeine is known for its potential to stimulate hair growth and has been the subject of research for its effects on hair follicles. In addition to caffeine, these shampoos may also contain other ingredients such as zinc, niacin, menthol, and castor oil. Some of the claimed benefits of these shampoos include maintaining natural hair growth, creating a noticeably thicker appearance, and energizing and strengthening the hair. The shampoos are designed to be used by massaging into the hair and scalp and leaving on for a few minutes before rinsing. The frequency of use is typically recommended for daily use for best results. The main ingredients in these shampoos include water, sodium laureth sulfate, caffeine, panthenol, and other compounds. While the shampoos are generally well-received for their potential benefits, it's important to note that individual experiences with the products may vary.