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Polycystic ovary syndrome


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

PCOS affects millions of women in the UK.

There are three features which lead to a woman being diagnosed with PCOS. Even if only two of them are present, this is enough to confirm the diagnosis. The features of PCOS include:

  • a number of cysts that develop around the edge of the ovaries (polycystic ovaries)
  • a failure in the release of eggs from the ovaries (ovulation)
  • a higher level of male hormones than normal, or male hormones that are more active than normal

These can lead to the following symptoms:

Read more about the symptoms of polycystic ovary syndrome.

What are polycystic ovaries?

Polycystic ovaries contain a large number of harmless cysts that are no bigger than 8mm each. Normal ovaries have only about half this number of cysts.

The cysts are under-developed follicles which contain eggs that haven't developed properly. Often in PCOS, these follicles are unable to release an egg, meaning ovulation doesn't take place.

Many women have polycystic ovaries without having the syndrome (without the symptoms). Some women have the syndrome, but have normal-looking ovaries on ultrasound.

Causes of polycystic ovary syndrome

The exact cause of PCOS is unknown, but it often runs in families.

Women who are overweight are more at risk of developing PCOS. Many women with PCOS have a family history of diabetes and high cholesterol.

It's also believed that insulin may play a role. Insulin is a hormone that controls sugar levels in the body. Many women with PCOS have too much insulin in their body, which contributes to the increased production and activity of male hormones. Being overweight increases the amount of insulin that your body produces.

Read more about the causes of polycystic ovary syndrome.

Treating polycystic ovary syndrome

There's no cure for PCOS, but the symptoms can be treated. Specific types of contraceptive pill may be prescribed to help regulate the menstrual cycle and improve hair growth. Lifestyle changes, such as losing weight, may help to control some of the symptoms.

Polycystic ovary syndrome is associated with an increased risk of problems in later life, such as type 2 diabetes and high cholesterol levels.

There are treatment options for infertility caused by PCOS. There's also medication to increase ovulation and, in some cases, surgery.

Many women with fertility problems due to PCOS can still have a baby.

Read more about treating polycystic ovary syndrome.

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The symptoms of PCOS usually become apparent in your late teens or early twenties. In many women, the only symptoms are menstrual problems or a failure to conceive.

Not all women with polycystic ovary syndrome (PCOS) have all of the symptoms. Each symptom can vary from mild to severe.

The classic symptoms of PCOS are:

Fertility problems

Polycystic ovary syndrome is one of the most common causes of female infertility. Many women discover they have PCOS when they're trying to get pregnant and are unsuccessful.

During each menstrual cycle the ovaries release an egg (ovum) into the uterus. This process is called ovulation and usually occurs once a month. Women with PCOS often fail to ovulate or they ovulate infrequently.

Risks in later life

Cardiovascular disease

Having PCOS can lead to an increased risk of:

These conditions can cause stroke or heart disease later in life.

This increased risk is associated with resistance to insulin (a substance released by the pancreas to control blood sugar levels), obesity and hormone imbalances.

Read more about the causes of polycystic ovary syndrome.

Endometrial cancer

Women who have had absent or irregular periods for many years have a higher-than-average risk of developing cancer of the womb lining (endometrial cancer).

However, the chance of getting endometrial cancer is still very rare. This risk can be minimised by certain treatments to regulate periods, such as the contraceptive pill or intrauterine system (IUS).

Read more about how polycystic ovary syndrome is treated.

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The exact cause of polycystic ovary syndrome (PCOS) is unknown, but the following factors often lead to its development.

Resistance to insulin

Insulin is a hormone produced by the pancreas to control the amount of sugar in the blood. It helps to move glucose out of the blood and into cells, where it is broken down to produce energy.

Insulin resistance means that the body's tissues are resistant to the effects of insulin. The body therefore has to produce extra insulin to compensate.

High levels of insulin cause the ovaries to produce too much testosterone (see below), which interferes with the development of the follicles and prevents normal ovulation.

Weight gain

Insulin resistance often makes it more difficult to lose weight, as raised insulin levels can lead to weight gain. Being overweight or obese makes the symptoms of PCOS more pronounced because excess fat causes the body to produce more insulin.

Hormone imbalance

Many women with PCOS are found to have an imbalance in certain hormones:

  • Raised levels of testosterone and other male sex hormones results in many of the symptoms of PCOS (all women produce testosterone, but normally in much lower levels than men).
  • Low levels of sex hormone binding globulin (SHBG), which means that testosterone levels are more active.
  • Raised levels of luteinising hormone (LH), which is created in the pituitary gland to stimulate ovulation and hormone production in the ovaries. This excess is thought to have an abnormal effect on the ovaries.
  • Raised levels of prolactin (only in some women with PCOS). This hormone usually stimulates the breast glands to produce milk in pregnancy.

The exact reason how and why this happens is not known. It's been suggested that the problem may start in the ovary itself, in the pituitary gland and part of the brain that controls it. Or it may be caused by the resistance to insulin.


Polycystic ovary syndrome (PCOS) can sometimes run in families. If any of your relatives, such as your mother, sister or aunt, have PCOS then the risk of you developing it is often increased.

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If you have any of the typical symptoms of polycystic ovary syndrome (PCOS) see your GP.

Your GP will ask you about your symptoms to try and rule out other causes and check your blood pressure.

Your GP or specialist may then request an ultrasound scan, which can show if you have polycystic ovaries (a chain of cysts is often seen, and the ovaries are enlarged). However, the diagnosis can often be confirmed without a scan.

You may also need a blood test to determine levels of:

  • hormones, such as luteinising hormone (LH), oestradiol, prolactin and testosterone
  • glucose and cholesterol, depending on which other features are present

Referral to a specialist

If you are diagnosed with PCOS, you're likely to be referred to a specialist – either a gynaecologist (specialist in treating conditions of the female reproductive system) or an endocrinologist (specialist in treating hormone problems).

Your specialist will discuss with you the best way to manage your symptoms. They will advise you on any lifestyle changes to make, and start you on any necessary medication.


If you have PCOS, you should request annual blood pressure checks checks to detect the possible long-term effects of the condition. If you are resistant to insulin you may also consider having your glucose levels checked annually.

Read more information about how polycystic ovary syndrome (PCOS) is treated.

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Polycystic ovary syndrome (PCOS) can't be cured, but the symptoms can be managed.

Treatment options can vary as someone with polycystic ovary syndrome (PCOS) may experience a range of symptoms, or just one. The treatment options may include:

  • losing weight and adopting a healthy lifestyle
  • hormone treatment, such as specific types of contraceptive pill or anti-androgen drugs which block the effects of male hormones on the body
  • a drug called metformin to improve the body's sensitivity to insulin
  • a fertility drug called clomifene, sometimes leading to more complex treatment such as IVF.
  • Vaniqa cream (eflornithine) to stop excess hair growth (hirsutism)
  • surgery to treat the ovaries known as laparoscopic ovarian drilling (LOD)

These options are discussed in more detail below.

Lifestyle changes

In overweight women, the symptoms and overall risk of developing long-term health problems due to polycystic ovary syndrome (PCOS) can be greatly improved by losing excess weight.

Losing weight will reduce the amount of insulin that your body needs to produce. This reduces testosterone levels and improves the chances of ovulation.

Menstrual and fertility problems will improve, along with a decrease in excessive hair growth and acne.

You can lose weight by following a suitable diet and doing 45-60 minutes of aerobic exercise every day. Your GP can refer you to a dietician, who will offer you advice. Weight loss of just 5% can lead to a significant improvement in PCOS.

Find out if you are a healthy weight.

A normal body mass index (BMI) is 19-25. If you have PCOS and your BMI is:

  • more than 30, you will be especially difficult to treat; in many areas of the UK a BMI above 30 will exclude you from receiving complex fertility treatments
  • more than 35, you're seriously at risk of medical problems
  • more than 40, the risk of medical problems is so high that pregnancy is inadvisable

Read more information and advice on how to lose weight.

Hormone treatment

Some anti-male hormone drugs can be used to block the 'masculine effects' of hormones, such as testosterone, which can cause some of the symptoms of PCOS (particularly excess facial hair and loss of hair from the head). These drugs include:

  • cyproterone acetate
  • spironolactone 
  • flutamide
  • finasteride

Hormone treatment can also control irregular or absent periods. The contraceptive pill may be recommended to induce regular periods. This will also reduce your long-term risk of cancer of the womb lining (endometrial cancer) if you don't have periods.

Gonadotrophins (hormones produced by the body that stimulate the ovaries) may be recommended for some women with PCOS who haven't responded to clomifene (see below). However, there's a risk that gonadotrophins may overstimulate the ovary and lead to multiple pregnancies. An alternative to this treatment is surgery (see below).


If you're trying to conceive but not ovulating, your ovaries can be stimulated with a fertility drug called clomifene.

Clomifene corrects your hormone imbalance and makes you more likely to ovulate, therefore improving your fertility.

Diabetes drugs

A diabetes drug called metformin can increase ovulation in women with PCOS, along with other treatments. It may also reduce health risks from insulin resistance and the effect of abnormal levels of male hormones. It can be taken with clomifene.

However, metformin is not a weight loss drug.

Vaniqa cream

Vaniqa cream blocks the action of an enzyme found in hair follicles that is needed for hair growth. The cream slows down the growth of unwanted facial hair, which may be a symptom of PCOS.

However, it doesn't remove hair or cure unwanted facial hair, so you may wish to use it alongside a hair-removal product.

Improvement may be seen as early as four to eight weeks after treatment.


A minor surgical procedure called laparoscopic ovarian drilling (LOD) may be a treatment option.

Under general anaesthetic, your doctor will make a small cut in your lower abdomen and pass a long telescope called a laparoscope through into your abdomen. The ovaries are then surgically treated using heat or a laser.

The aim is to destroy the tissue that's producing androgens (male hormones).

LOD has been found to lower levels of testosterone and luteinising hormone (LH) and raise levels of follicle-stimulating hormone (FSH). This corrects your hormone imbalance and therefore restores the normal function of your ovaries.

The National Institute for Clinical Excellence (NICE) guidance recommends that women with PCOS who haven't responded to clomifene should be offered LOD because it is as effective as gonadotrophin treatment (see above) and is not associated with multiple pregnancy.

Other medications

  • If you're overweight you may be prescribed a weight-loss drug, such as orlistat.
  • If you have high levels of cholesterol in your blood, you may be prescribed a cholesterol-lowering medication (statin) such as simvastatin. This is unlikely to be prescribed if you're still planning on having a baby.
  • You may also be offered treatment for acne.

Pregnancy risks

If you have PCOS, you have a higher risk of pregnancy complications, such as high blood pressure (hypertension), pre-eclampsiagestational diabetes and miscarriage.

Women with PCOS who are obese have a particularly high risk, especially if they also have high testosterone levels and body hair growth.

The risk of miscarriage can be reduced by losing weight before pregnancy (if you're obese), treating high luteinising hormone (LH) levels and treating insulin resistance.

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