Open a PDF version to print this topic

HealthInfo Canterbury

Overview of polycystic ovary syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is a very common condition that happens in 5 to 10% of young women. It tends to run in families, but it isn't caused by a single gene.

Women with PCOS may have irregular or no periods, infertility, increased hair growth, acne, and sometimes scalp hair loss. Being overweight is common but it isn't caused by the PCOS.

The name is a bit of a problem. Some women whose ovaries look as if they have a lot of cysts have normal periods and hormones, and some women whose hormones suggest they have PCOS have normal-looking ovaries. When there are cysts, they're small (less than 1 cm) and don't cause pain.

Causes of PCOS

We don't fully understand what causes PCOS, but it seems to involve several things. The pituitary gland, a small gland at the base of the brain that controls many of our hormones, seems to make the ovaries work too hard. The ovaries then make too many androgens (male-type hormones).

These hormones interfere with the woman's periods and can give her acne and make her grow more body hair. Some women also lose hair from their scalp (alopecia). The ovaries tend to be bigger than normal and have small cysts around the outside that are filled with fluid.

Many women with PCOS are overweight, but slim women also get it. Some women with PCOS also have a problem known as insulin resistance.

Insulin is a hormone that controls the level of sugar in our blood. Insulin resistance means the body isn't very sensitive to insulin. It has to make much more to keep the blood sugar normal. This high level of insulin makes the ovaries make more of the male-type hormones. So women with PCOS may have a higher risk of diabetes and heart disease later in life, especially if they're overweight.

If you have problems with hair growth (hirsutism), irregular periods or infertility, your doctor may suggest some tests. These could include blood tests to look for:

Your doctor might also suggest you have an ultrasound examination of your ovaries.

Treatments for PCOS

You can be treated for excessive hair growth and acne, or infertility, but you can't be treated for both at the same time. So you will need to decide which is most important for you.

Hirsutism and acne

If you don't have too much facial and body hair, you may be able to control it with normal cosmetic methods. These include plucking, bleaching, waxing, depilatory creams which dissolve the hair, and shaving. Some people are worried that shaving will make their hair grow more rapidly but this doesn't happen. All these methods are temporary, but they don't cost much. Electrolysis and laser therapy are more permanent but cost more.

If you have quite bad hair growth, you might need medical treatment. The most common medicines are the anti-androgen drugs spironolactone or cyproterone acetate. These slow down hair growth and make the hair finer. They may take up to six months to work, and the effect gradually wears off if you stop taking them.

Another useful treatment is the contraceptive pill, which helps to control the effect your pituitary gland has on your ovaries. One preparation known as Ginet 84 is especially good, because it also controls the effects of the male-type hormones.


Treatment can help if PCOS is making you infertile. If you're overweight, losing weight and keeping more physically active will also improve fertility.

There are also drugs that can stimulate ovulation (releasing an egg).

Clomiphene is the most common one. Women take it for five days, beginning on day two after the start of a period. If you aren't having periods, you can start the tablets any time. It may result in a period about a month later. You'll have a blood test to check for ovulation between days 22 and 24.

If clomiphene doesn't work, then you may try gonadotrophin injections. This is a more powerful treatment and you'll need to be carefully monitored. Talk to your doctor for more details.

Insulin resistance

Metformin has been used for many years to treat diabetes. We also use it to treat PCOS. It probably works by reducing the amount of insulin in your blood, which means your ovaries make less of the male-type hormones. It might also make your periods more regular and increase the chances clomiphene will lead to ovulation.

If you're overweight, losing weight can also improve insulin resistance, make your periods more regular and improve your hormones.

Side effects of treatments

FDP birth control pillsAll medicines have side effects. These are some of the side effects of treatment for PCOS.

Ginet 84


Cyproterone acetate


These side effects are less severe if you start on a low dose and build up gradually. People with severe heart, lung, liver or kidney problems shouldn't take metformin. You shouldn't take it on days when you're sick.

  HealthInfo recommends the following pages

On the next page: Eating well with polycystic ovary syndrome

Written by the Department of Endocrinology, Christchurch Hospital. Adapted by HealthInfo clinical advisers. Last reviewed April 2018.

See also:

About women's bodies

Irregular periods

Birth control images courtesy of BrandonSigma at

Page reference: 70671

Review key: HIPCO-15994