Causes of Hair Thinning in Men and Women Hair thinning is one of the most common beauty and health concerns affecting both men and women. While losing 50–100 hairs per day is completely normal, noticeable thinning, widening parts, or receding hairlines may signal underlying causes that deserve attention. Understanding why hair thinning happens is the first step toward choosing the right prevention and support strategies. Below, we explore the most common causes of hair thinning in both men and women. Genetic Hair Loss (Androgenetic Alopecia) The most common cause of hair thinning is androgenetic alopecia, also known as male or female pattern hair loss. In men, it often appears as a receding hairline or thinning at the crown. In women, it usually presents as a gradual thinning along the part line. This condition is influenced by genetics and hormones, particularly sensitivity to dihydrotestosterone (DHT), a derivative of testosterone . Over time, hair follicles shrink, producing ...