Androgenetic alopecia, also called common baldness in men and hereditary loss in women, is the most common cause of hair loss in men and women. A common trait, from the genetic point of view, is that it is produced by androgens in men and sensitivity to them in women.
It can begin during adolescence or early adulthood in both sexes and manifest itself fully at the age of 40.
According to various statistics, it affects about 25% of men between 25 and 35, 40% in their 40s, and 50% over 50, with a rising percentage in groups we consider to be the elderly. In women it can affect as much as about 28%, although there are no detailed studies on the subject.
For proper understanding of alopecia, we must start by saying that hair growth is cyclical and goes through three phases:
1º growth phase (anagen), which lasts from 2 to 6 years, where the hair grows 1cm every month.
2º transistional phase (catagen), lasting about 3 weeks
3º resting phase (telogen), between 80-100 hairs imperceptibly fall a day for about 3 or 4 months.