Yes, shampoos work for thinning hair. There are a few different ways that they can help. First, they can help to cleanse the scalp and hair of build-up from styling products and other debris. This can allow the hair to look its best and can also help to prevent further damage. Second, shampoos can help to nourish the scalp and hair with essential nutrients that may be lacking in the diet. This includes things like biotin, zinc, and omega-3 fatty acids. These nutrients are important for healthy hair growth. Third, shampoos can help to increase blood circulation to the scalp. This helps to deliver more oxygen and nutrients to the follicles which can promote healthy growth. Finally, some shampoos contain ingredients that directly target thinning hair such as ginseng or green tea extract.