the excessive growth of hair on a person’s body where only downy hairs usually grow.

There are several kinds of hypertrichosis. Heterogeneous hypertrichosis occurs in girls and women; it is the appearance of a beard, moustache, or male-type hair growth. (In men, pubic hair grows in a diamond shape; in women, in the form of a triangle with the upper boundary the horizontal side.) Hair growth increases during the period of sexual development and before or during the climacteric. Heterochronous hypertrichosis is the premature appearance of hair as a secondary sex characteristic (the appearance of a beard, moustache, or pubic hair in children). It is caused by a developmental anomaly or a disease of the endocrine glands. Heterotypic hypertrichosis is an increased amount of hair in unusual places, such as the small of the back. Hypertrichosis can be partial, local, or distributed over the whole body. Limited hypertrichosis can be either hereditary or elicited by prolonged mechanical, chemical, thermal, or physical trauma.

In women with excessive growth of downy hairs on the face or extremities, pulling out the hairs, shaving, or applying greasy creams or depilatories can cause significant thickening of the hairs, which become coarse and stiff and begin to grow faster than usual. An application of a 10-15 percent solution of hydrogen peroxide makes the hairs colorless and less noticeable but does not curtail their growth. Depilatories (preparations which dissolve the core of the hair and do not affect the papillae from which they grow) can be applied in extreme cases and only on covered parts of the body. The best treatment consists of electroepilation with the aid of electrolysis, ultrahigh frequency, and diathermy.