There is no single "best" shampoo for hair loss. Different types of shampoo may be more or less effective for different people. Generally, shampoos that contain natural ingredients, such as tea tree oil, biotin, and saw palmetto, are thought to be beneficial for hair loss. It may also be helpful to use a shampoo that is specifically formulated for thinning hair. Additionally, it is important to use a gentle shampoo and avoid over washing the hair.