A shampoo alone cannot usually prevent hair loss. Shampoos are used to clean hair and scalp. They can be very effective in relieving certain conditions like dandruff, itching, irritations and other disorders of the scalp. As hair loss is usually of genetic or hormonal origin, it is necessary to target the problem further.  Shampoos are very necessary in the treatment of hair loss becasue they must be used before any effective treatment to ensure the penetration of active ingredients into the surface of the scalp. Rinse-free lotions are preferred when looking for an effective anti-hair loss product. These products are applied to the scalp and should not be rinsed in order to allow them to penetrate. Some shampoos are formulated specifically to ensure better penetration of lotions without rinsing.