Causes of Excess Hair
It's the level of hormones (androgens - mainly testosterone) at puberty which cause the hair follicles to change from producing the fine downy vellus hair of childhood to producing coarser longer and darker terminal hair on certain parts of the body.
The hair that grows at this time is often called androgenic hair because of the particular type of hormones involved. The hair follicles in specific parts of the body and in different sexes and individuals are more sensitive to the effect of the androgens.
Areas on the human body that develop terminal hair growth due to rising androgens in both sexes, men and women, are the underarms and the pubic area. Men also normally have androgenic hair growth in other areas. In particular puberty sees the appearance of facial, chest and abdominal hair.
While females tend to have more vellus hair and males terminal hair on areas such as arms and legs the amount of hair which occurs varies among individuals. The variation is chiefly due to genetics.
In particular, genetic differences affect the level of sensitivity of the hair follicles to the androgens and the level of androgens themselves in different individuals and cause hair to grow thicker more readily and at a more rapid rate.
There are some medical causes (see below) for more extreme cases of excess hair (which is called hirsutism in women when terminal hair grows in areas where it is unexpected or hypertrichosis among the general population in medicine) but excess hair can also simply be seen as any unwanted hair and is reason enough in itself for looking at hair removal methods.
Medical problems aside, unwanted hair is all about cultural and social attitudes and what is acceptable in one culture and era will be seen as undesirable in another (I doubt Charlotte Bronte or Calamity Jane ever shaved their legs or worried about removing hair from their armpits).
Medical Causes of Excess Hair
Extreme cases of excess hair are usually caused by a high level of androgens circulating in the blood stream. Some conditions and medicines in particular cause an increase in the level of male androgen hormones in females (all women normally have some level of male hormones) and may give rise to excess hair. The main conditions which may promote hirsutism are
- Polycystic Ovary Syndrome
- Cushing's disease
- Tumors in the ovaries or adrenal glands
- Congenital adrenal hyperplasia
- Obesity (there is some evidence that high levels of insulin circulating in the bloodstream may lead to an increase in excess hair).
In these cases the treatment of the condition (or a change in medication) may lead to a reduction in the problem of excess hair although the existing hair may have to be removed by normal hair removal methods.
In order to determine if hair is excessive in either males or females, there is a scoring system (the Ferriman-Gallwey score)which doctors may use to assess the problem.