Androgenetic alopecia, also known as male pattern baldness (MPB), is the most common cause of hair loss in men. It begins as a receding hairline or bald spot on the top of the head, progressing over time to the sides and rear of the head. The factors that drive this type of hair loss can also cause hair thinning, where hairs grow smaller in diameter, according to the American Academy of Dermatology (AAD).
Male pattern baldness affects males of all ages. Two-thirds of American men will experience some degree of hair loss due to MPB by age 35, and approximately 25% of men begin the process before they reach age 21, according to the American Hair Loss Association (AHLA).
