Hard and coarse hair may be caused by both genetic and external factors. 1. Genetic factors: Generally speaking, if the parents have hard and coarse hair, it is more likely that the child will have hard and coarse hair. Generally, it is characterized by low oil and moisture content, dry hair and hard hair. 2. External factors: some men often shave their heads, hair is cut at the root, the cross-cutting area becomes larger, and the newly grown hair becomes coarser and harder. When the hair is coarse and hard, you can choose a more moisturizing and nourishing type of shampoo products, shampooing water temperature should not be too high, shampooing coated with moisturizing effect of hair care products such as essential oils, to maintain the hair has enough moisture, can improve the problem of coarse and hard hair.