What Causes Hair Loss: Although there are many causes, The most common cause of hair loss is known as androgenetic alopecia, or male pattern baldness (in men), and female pattern baldness (in woman). It is caused by the effects of Dihydrotestostrone (DHT) a hormonal by product of testosterone that has been shown to shorten the growth phase of hair by slowing follicle growth. While DHT is essential for early development, it can attach to hair follicles as men and woman get older, which causes the follicle to get smaller and smaller, and the hairs to get thinner eventually falling out. Male pattern baldness is something that 7 - 15% of American males experience by age 25, and almost 40% by age 35. It is a natural, age-related change in the body, and represents over 95% of all hair loss in men. Female pattern baldness may commonly begin at any age through 50 or later. It affects about 20 million women in the US alone, and is highly correlated to genetics.