Overview - Polycystic ovary syndrome (PCOS)

Polycystic ovary syndrome (PCOS) affects how a woman's ovaries work. It can affect many aspects of your health.

It's a common condition that can affect your:

  • hormones
  • periods
  • fertility

It affects almost 1 in 5 women of childbearing age.

PCOS can cause pregnancy complications. But there are things you can do to reduce your risk of complications.

There is no cure for PCOS. But there are many treatments available.

The treatment you get depends on whether or not you are hoping to become pregnant.

Polycystic ovaries

Polycystic ovaries are bigger than healthy ovaries. They contain a large number of harmless follicles. The follicles are under-developed sacs that release eggs when you ovulate.

Polycystic ovaries have twice the number of follicles than healthy ovaries do. In polycystic ovary syndrome (PCOS), these sacs are often unable to release an egg. This means that ovulation doesn't take place each month.

This can cause you to stop having periods, or to have irregular periods. It can also mean you have difficulty becoming pregnant.

Signs and symptoms

If you have signs and symptoms of PCOS, they'll usually appear during your late teens or early 20s.

They can include:

  • irregular or light period or no periods at all
  • difficulty getting pregnant
  • excessive hair growth (hirsutism)
  • weight gain
  • thinning hair and hair loss from the head
  • oily skin or acne

Read more about symptoms of PCOS

Causes of PCOS

The exact cause of PCOS is unknown. It's thought to be linked to abnormal hormone levels in the body, including high levels of insulin.

Read more about the causes of PCOS

Diagnosing PCOS

The 3 main features of PCOS are:

  • irregular periods
  • excess androgen - high levels of 'male hormones' in your body
  • polycystic ovaries

Irregular periods means that you do not have a period every 3 to 5 weeks. This could be a sign that your ovaries are not producing an egg each month.

Excess androgen may cause physical signs such as excess facial or body hair.

With polycystic ovaries your ovaries become enlarged. They contain many fluid-filled sacs (follicles). These surround the eggs. Despite the name, you do not actually have cysts.

If you have at least 2 of these features, you may be diagnosed with PCOS.

Read more about diagnosing PCOS

Treating PCOS

There's no cure for PCOS. But you can manage the symptoms. You can improve symptoms and long-term health problems by losing excess weight.

Medications are also available to treat symptoms such as:

  • excessive hair growth
  • irregular periods
  • fertility problems

If fertility medications don't work, you might have a simple surgical procedure. With treatment, most women with PCOS are able to get pregnant.

Read more about treatment for PCOS

Risks in later life

Having PCOS increases your chances of developing other health problems in later life.

For example, women with PCOS are at an increased risk of developing:

You may have a higher risk of getting endometrial cancer (cancer of the womb) particularly if you are overweight and have irregular periods.

The risk is very small but may happen if you have:

  • less than 3 or 4 periods per year for many years
  • no periods at all for many years

If you have PCOS and you have fewer than 4 periods per year, talk to your GP.

You can reduce the risk of endometrial cancer by using treatments such as:

  • contraceptive pills to ensure regular periods
  • a short course of a tablet containing progesterone (a hormone normally produced in the female body) ensures bleeds every 2 to 3 months

Risks of complications in pregnancy

PCOS reduces the likelihood of pregnancy. It increases the risk of miscarriage and also the risk of medical complications in pregnancy, diabetes being one. You should maintain a normal weight before becoming pregnant.

To reduce your risk of complications:

  • try and keep your weight healthy - lose weight if you are overweight
  • quit smoking - if you smoke
  • eat a wide variety of healthy foods
  • exercise regularly


Content supplied by the NHS and adapted for Ireland by the HSE

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This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.

Page last reviewed: 23 March 2021
Next review due: 23 March 2024