Hair growth

Most scalp hair grows steadily. After a growth phase that lasts between 2 and 6 years, scalp hair enters a resting phase that lasts 2 to 3 months. Hair is shed at the end of the resting phase.

A person normally sheds from 50 to 100 hairs a day. After a hair is shed, it is replaced by a new hair from the same follicle, and the growing cycle starts again. Scalp hair grows about 0.5 in. (1.3 cm) per month. As people age, their rate of hair growth slows.