Polycystic ovary syndrome (PCOS) is a common condition that affects how a woman’s ovaries work.

The three main features of PCOS are:

  • irregular periods – which means your ovaries don't regularly release eggs (ovulation)
  • excess androgen – high levels of "male hormones" in your body, which may cause physical signs such as excess facial or body hair (see signs and symptoms below)
  • polycystic ovaries – your ovaries become enlarged and contain many fluid-filled sacs (follicles) which surround the eggs (it's important to note that, despite the name, if you have PCOS you don't actually have cysts)

If you have at least two of these features you may be diagnosed with PCOS. Read more about diagnosing PCOS.

Polycystic ovaries

Polycystic ovaries contain a large number of harmless follicles that are up to 8mm (approximately 0.3in) in size. The follicles are under-developed sacs in which eggs develop. In PCOS, these sacs are often unable to release an egg, which means that ovulation doesn't take place.

It's difficult to know exactly how many women have PCOS, but it's thought to be very common affecting about one in every five women in the UK. More than half of these women don't have any symptoms.

Signs and symptoms

If you do have signs and symptoms of PCOS, they'll usually become apparent during your late teens or early twenties. They can include:

PCOS is also associated with an increased risk of developing health problems in later life, such as type 2 diabetes and high cholesterol levels.

What causes PCOS?

The exact cause of PCOS is unknown, but it often runs in families. It's related to abnormal hormone levels in the body, including high levels of insulin.

Insulin is a hormone that controls sugar levels in the body. Many women with PCOS are resistant to the action of insulin in their body and produce higher levels of insulin to overcome this.

This contributes to the increased production and activity of hormones such as testosterone. Being overweight or obese also increases the amount of insulin your body produces.

Read more about the causes of PCOS.

Treating PCOS

There's no cure for PCOS, but the symptoms can be treated. Speak to your GP if you think you may have the condition.

If you have PCOS and you're overweight, losing weight and eating a healthy, balanced diet can make some symptoms better.

Medications are also available to treat symptoms such as excessive hair growth, irregular periods and fertility problems.

If fertility medications are ineffective, a simple surgical procedure called laparoscopic ovarian drilling (LOD) may be recommended. This involves using heat or a laser to destroy the tissue in the ovaries that's producing androgens, such as testosterone.

With treatment, most women with PCOS are able to get pregnant.

Read more about treating PCOS.

Page last reviewed: 18/03/2016

Next review due: 18/03/2018