Hirsutism is a condition in which too much hair grows on the face or body. Hirsutism can occur in both men and women, but unlike beard hirsutism in men, which can suggest masculinity and virility, female hirsutism is not seen as a desirable trait and it is considered as a problem.

Women who have hirsutism have dark, thick hair on their face, chest, abdomen and back. This thick, dark hair is different from the fine hair that some women have on their upper lip, chin, breasts or stomach, or the "baby" vellus hair all over their body. Women from certain ethnic groups tend to have more body hair than others. This does not mean that they have hirsutism, rather it may be the normal state for some people depending on their ethnicity. For example, women with a Mediterranean background are more likely to have higher, normal level of body hair. In contrast women of East Asian extraction tend to have much less body hair.

Hirsutism is a condition where the normally small, vellus body hair follicles of an individual respond to hormones by increasing their size and shape and start to produce large, pigmented hair fibers. The vellus hair follicles turn into terminal hair follicles in response to androgen hormones. Because hair follicles that are androgen responsive are only present in a certain pattern over the skin, hirsutism is only seen in certain areas such as the beard and moustache area.

Hirsutism is very common and often improves with medical management. Prompt medical attention is important, because delaying treatment makes successful treatment more difficult and the development of hirsutism may have long-term health consequences depending on what is causing it.