Each hair depends on a sebaceous gland which secretes sebum to hydrate it. Certain factors mean that, sometimes, it produces too much:hormonal disorders, very long hair (they are heavier so they "pull" more on the sebaceous glands), an unsuitable shampoo...
To counter the problem, we tend to use drying products that irritate the scalp, which leads to itching, dandruff, and... hair that re-greases even faster. Yes, to respond to irritation, the sebaceous glands produce even more sebum. A real vicious circle!
It is therefore recommended to use mild or treating shampoos, which purify the scalp. Sebum is then regulated naturally and the hair is less greasy.
