Is shampoo necessary? Fewer people are using it. They are changing their habits. A study on shampoo said: "People are working from home…and fewer people are smoking, so [they] are using less shampoo." Shampooing often may be why hair gets greasy. It makes the head dry, so the head makes more oil.
Many people say shampoo is good. They say it is gentle on your head and makes the hair shine. The hair's oil doesn't clean it. A hair loss clinic said we must use shampoo when we sweat after exercise or using a sauna. Shampoo removes bacteria and cleans the extra oil from your head. The clinic said shampoo is good for greasy hair.