Hereditary thinning is a form of hair loss in women. It occurs in all races and can be inherited from either the mother's or father's side of the family, or both. The rate at which the hair loss occurs varies between women.

Hereditary thinning can occur in normal, healthy women. Women with this type of hair loss retain their hairlines and thin diffusely, usually on the top of their heads. They may notice that their parts are wider on the top than on the sides. A normal adult scalp sheds approximately 100 hairs per day. A woman with hereditary thinning will find that, although her hair is thinning, she's not shedding more than normal. This type of hair loss is treatable with twice-daily applications of minoxidil . Such treatments should be discontinued if a woman becomes pregnant. Because of hormonal activity, chances are good that little hair loss will occur during pregnancy and treatments may be resumed after the baby is born.

It's not known precisely why monoxidil works, but one theory is that it works by stimulating hair follicle growth.

While most people are familiar with hair loss resulting from chemotherapy treatments, other medications including certain cardiac medications and antidepressants have also been reported to cause hair thinning. Some androgen-dominant birth control pills can also be a culprit, and elderly women may experience age-related hair thinning. Hair loss can also be a sign of an eating disorder such as anorexia or bulimia.

Normally, a single hair will grow for 2-10 years and then go into a resting phase, with each hair in a different phase at any given time. However, severe emotional distress can send a lot of the hair into a dormant phase resulting in thinning. It is called telogen effluvium.

Inappropriate use or abuse of hair cosmetics can also lead to hair loss. Overusing perms or straighteners, wearing tight pigtails, ponytails, or cornrows, and sleeping with sponge rollers in your hair can all result in hair loss.