Androgenetic alopecia is a type of hair loss that is inherited from either or both the mother and the father. Also known as male- or female-pattern hair loss, it is the most common cause of hair loss.

The condition occurs when the growth (anagen) phase of the hair growth cycle becomes shorter and shorter. A genetic sensitivity to androgens, a type of hormone, causes hair follicles—where hair growth begins—to sprout hairs that are thinner than normal. The hairs become thinner and thinner, and eventually the follicles die away.

• In men, hair loss occurs on the front hairline and forehead and on the top of the head. Bald spots are noticeable.
• In women, hair loss occurs as thinning of hair on the top of the head. Women tend to keep their front hairline and do not generally develop bald spots.