As surprising as may sound, women experience hair loss almost as often as men, though normally not to the same degree. Excessive hair loss can be brought on by many different factors. The most common is androgenetic alopecia. In men, this is called male pattern baldness. In women, it is called female pattern baldness and follows a very different pattern than in men.

Female pattern baldness can affect as many as 40 percent of all women. The cause is genetic, meaning it is inherited through the family genes. The more direct cause in women can be one of two things. Either a surplus of the male hormone, testosterone, or a shortage of female hormones that put the male hormones out of balance will result in a buildup of the testosterone derivative, DHT. DHT is considered to be the causative factor because it bonds to the hair follicles and chokes the hair off.

One problem that is unique to women that contributes to hair loss is the taking of oral contraceptives. Many of them have a high androgen index, meaning they put male hormones in the ascendancy over the female. Any hormone based birth control has the possibility of causing hair loss.

Some diseases, such as polycystic ovarian syndrome, can throw the hormones out of balance and cause hair loss. It can also be brought on by medical conditions that are transitory, such as child birth. It is believed that these cases are caused by the stress of the condition as much or more than the condition itself.

Some hair loss is caused by habitual behaviors and certain hairstyles. Though it is rare, some women have the habit of pulling their hair when they are nervous or deep in thought. Certain hairstyles can also cause a form of hair loss known as traction alopecia. Corn rows, tight braids, tight ponytails, and other hairstyles that pull on the hair can cause the roots to come loose and the hair to fall out.

One of the most common forms of hair loss in women is an interruption of the normal cycle of hair growth called telogen effluvium. Under normal conditions, as much as 1/3 of the hair is at the end of its growth phase and entering a resting state known as telogen. At the end of this phase, the hair dies and falls out to replaced by a new strand at the beginning of the growth phase.

While this condition is not excessive under normal conditions, certain stressful events, childbirth, surgery, severe illness, depression, or just being under extreme stress can throw the cycle out of balance and cause more hair than normal to enter the telogen phase. When this happens, more than the normal amount of hair, up to half or more, can fall out, leaving an appearance of balding before the new hair begins to grow in.

Another common cause is known as alopecia areata, or losing hair in clumps. While this condition is rare in women, it is also very stressful when a wad of hair falls out leaving a bald spot the size of a quarter or fifty cent piece. Normally, this can be combed over until the hair grows back naturally, but in extreme cases, several clumps can come out at once. Conditions of extreme stress can lead to this more generalized form alopecia areata and lead to a woman needing a wig to cover the patches until her hair can grow back.

Certain medications or combinations of medications, chemotherapy for example, can change the chemistry of the hair and cause it to die prematurely. This is the reason most people who undergo chemotherapy lose their hair within a month of starting the treatment.