Hairy body or face - Causes of hirsutism

Hirsutism is caused by an increase in male sex hormones called androgens, or an increased sensitivity to them.

There are several different types of androgens. The most well known is testosterone.

In men, testosterone is involved in making sperm and in the development of male sexual characteristics, such as the voice getting deeper. Testosterone is also found in small amounts in women, where it may:

increase your sex drive
affect your periods (menstrual cycle)
affect your fertility

Testosterone levels may be normal in around half of all women with hirsutism.

Other androgens include:

dehydroepiandrosterone
androstenedione

These are precursors of testosterone, which means they will go on to become testosterone.

Premenopausal women

There are a number of different causes that may explain hirsutism in women who have not yet started the menopause (when a woman’s periods stop).

However, in around 23% of hirsutism cases, there are no obvious causes. This is known as idiopathic hirsutism.

Polycystic ovary syndrome (PCOS)

Most of the excess androgen activity in premenopausal women is due to an underlying condition known as polycystic ovary syndrome (PCOS).

PCOS is thought to be the cause of hirsutism in around 72% of cases.

PCOS is a condition in which women have a number of small, fluid-filled sacs (cysts) around the edge of their ovaries (the pair of reproductive organs that produce eggs and sex hormones in women).

As well as causing excessive hair growth, PCOS can also cause:

irregular periods
weight gain
acne

Many women with PCOS have an imbalance of male sex hormones, which can include high levels of testosterone.

Increased sensitivity

Just under a quarter of premenopausal women with hirsutism have normal androgen levels. It is thought that if your androgen levels are normal, your body may be more sensitive to them, meaning they have a greater effect on your body.

Other causes

In a small number of cases, hirsutism in premenopausal women may be caused by:

Cushing’s syndrome – a rare hormonal disorder that causes sudden weight gain and bloating around the chest and stomach
congenital adrenal hyperplasia – an inherited condition that affects the adrenal glands (two glands above the kidneys that produce steroid hormones, and male and female sex hormones)
a tumour (growth) that produces androgens
medicines – such as anabolic steroids (drugs that are often used illegally to build muscle and improve athletic performance)
acromegaly – a hormonal disorder that causes the body to produce too much growth hormone, causing abnormal growth of the hands and feet
being overweight or obese – you will be advised to lose weight

Menopausal women

Menopausal women are those who have started the menopause (when a woman’s periods stop) and have not had a period for a year. During the menopause, several of your body's hormones change, which can cause symptoms such as hot flushes.

For some women, as hormone levels change, there will be a high amount of testosterone (an androgen) left in the body, which can cause hirsutism. Hirsutism in post-menopausal women is also known as ovarian hyperthecosis.