If you experience symptoms of polycystic ovary syndrome (PCOS), they'll usually become apparent in your late teens or early 20s.

Not all women with PCOS will have all of the symptoms, and each symptom can vary from mild to severe.

Some women only experience menstrual problems or are unable to conceive, or both.

Common symptoms of PCOS include:

• irregular periods or no periods at all
• difficulty getting pregnant (because of irregular ovulation or failure to ovulate)
• excessive hair growth (hirsutism) – usually on the face, chest, back or buttocks
• weight gain
• thinning hair and hair loss from the head
• oily skin or acne

You should talk to your GP if you have any of these symptoms and think you may have PCOS.

Fertility problems

PCOS 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 (womb). This process is called ovulation and usually occurs once a month.

But women with PCOS often fail to ovulate or ovulate infrequently, which means they have irregular or absent periods and find it difficult to get pregnant.

Risks in later life

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

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

• type 2 diabetes – a lifelong condition that causes a person's blood sugar level to become too high
• depression and mood swings – because the symptoms of PCOS can affect your confidence and self-esteem
• high blood pressure and high cholesterol – which can lead to heart disease and stroke
• sleep apnoea – overweight women may also develop sleep apnoea, a condition that causes interrupted breathing during sleep

Women who have had absent or very irregular periods (fewer than 3 or 4 periods a year) for many years have a higher than average risk of developing cancer of the womb lining (endometrial cancer).

But the chance of getting endometrial cancer is still small and can be minimised using treatments to regulate periods, such as the contraceptive pill or an intrauterine system (IUS).

The exact cause of polycystic ovary syndrome (PCOS) is unknown, but it's thought to be related to abnormal hormone levels.

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 from blood into cells, where it's broken down to produce energy.

Insulin resistance means 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 causes the ovaries to produce too much testosterone, which interferes with the development of the follicles (the sacs in the ovaries where eggs develop) and prevents normal ovulation.

Insulin resistance can also lead to weight gain, which can make PCOS symptoms worse, as having excess fat causes the body to produce even more insulin.

Hormone imbalance

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

• raised levels of testosterone – a hormone often thought of as a male hormone, although all women usually produce small amounts of it
• raised levels of luteinising hormone (LH) – this stimulates ovulation, but may have an abnormal effect on the ovaries if levels are too high
• low levels of sex hormone-binding globulin (SHBG) – a protein in the blood, which binds to testosterone and reduces its effect
• raised levels of prolactin (only in some women with PCOS) – a hormone that stimulates the breast glands to produce milk in pregnancy

The exact reason why these hormonal changes occur is not known.

It's been suggested that the problem may start in the ovary itself, in other glands that produce these hormones, or in the part of the brain that controls their production. 

The changes may also be caused by the resistance to insulin.

Genetics

PCOS sometimes runs in families. If any relatives, such as your mother, sister or aunt, have PCOS, the risk of you developing it is often increased.

This suggests there may be a genetic link to PCOS, although specific genes associated with the condition have not yet been identified.

See your GP if you have any typical symptoms of polycystic ovary syndrome (PCOS).

Your GP will ask about your symptoms to help rule out other possible causes, and check your blood pressure.

They'll also arrange for you to have a number of hormone tests to find out whether the excess hormone production is caused by PCOS or another hormone-related condition.

You may also need an ultrasound scan, which can show whether you have a high number of follicles in your ovaries (polycystic ovaries). The follicles are fluid-filled sacs in which eggs develop. 

You may also need a blood test to measure your hormone levels and screen for diabetes or high cholesterol.

Diagnosis criteria

A diagnosis of PCOS can usually be made if other rare causes of the same symptoms have been ruled out and you meet at least 2 of the following 3 criteria:

• you have irregular periods or infrequent periods – this indicates that your ovaries do not regularly release eggs (ovulate) 
• blood tests showing you have high levels of "male hormones", such as testosterone (or sometimes just the signs of excess male hormones, even if the blood test is normal)
• scans showing you have polycystic ovaries

As only 2 of these need to be present to diagnose PCOS, you will not necessarily need to have an ultrasound scan before the condition can be confirmed.

Referral to a specialist

If you're diagnosed with PCOS, you may be treated by your GP or referred to a specialist, either a gynaecologist (a specialist in treating conditions of the female reproductive system) or an endocrinologist (a specialist in treating hormone problems).

Your GP or specialist will discuss with you the best way to manage your symptoms. They'll recommend lifestyle changes and start you on any necessary medication.

Follow-up

Depending on factors like your age and weight, you may be offered annual checks of your blood pressure and screening for diabetes if you're diagnosed with PCOS.

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

Treatment options can vary because someone with PCOS may experience a range of symptoms, or just 1.

The main treatment options are discussed in more detail below.

Lifestyle changes

In overweight women, the symptoms and overall risk of developing long-term health problems from PCOS can be greatly improved by losing excess weight.

Weight loss of just 5% can lead to a significant improvement in PCOS.

You can find out whether you're a healthy weight by calculating your body mass index (BMI), which is a measurement of your weight in relation to your height.

A normal BMI is between 18.5 and 24.9. Use the BMI healthy weight calculator to work out whether your BMI is in the healthy range.

You can lose weight by exercising regularly and eating a healthy, balanced diet.

Your diet should include plenty of fruit and vegetables, (at least 5 portions a day), whole foods (such as wholemeal bread, wholegrain cereals and brown rice), lean meats, fish and chicken.

Your GP may be able to refer you to a dietitian if you need specific dietary advice.

Read more about losing weight, healthy eating and exercise.

Medications

A number of medications are available to treat different symptoms associated with PCOS.

These are described below.

Irregular or absent periods

The contraceptive pill may be recommended to induce regular periods, or periods may be induced using an intermittent course of progestogen tablets (which are usually given every 3 to 4 months, but can be given monthly).

This will also reduce the long-term risk of developing cancer of the womb lining (endometrial cancer) associated with not having regular periods.

Other hormonal methods of contraception, such as an intrauterine system (IUS), will also reduce this risk by keeping the womb lining thin, but they may not cause periods.

Fertility problems

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

The majority of women can be successfully treated with a short course of tablets taken at the beginning of each cycle for several cycles.

If these are not successful, you may be offered injections or IVF treatment. There's an increased risk of a multiple pregnancy (rarely more than twins) with these treatments.

A medication called clomifene is usually the first treatment recommended for women with PCOS who are trying to get pregnant.

Clomifene encourages the monthly release of an egg from the ovaries (ovulation).

If clomifene is unsuccessful in encouraging ovulation, another medication called metformin may be recommended. 

Metformin is often used to treat type 2 diabetes, but it can also lower insulin and blood sugar levels in women with PCOS.

As well as stimulating ovulation, encouraging regular monthly periods and lowering the risk of miscarriage, metformin can also have other long-term health benefits, such as lowering high cholesterol levels and reducing the risk of heart disease.

Metformin is not licensed for treating PCOS in the UK, but because many women with PCOS have insulin resistance, it can be used "off-label" in certain circumstances to encourage fertility and control the symptoms of PCOS.

Possible side effects of metformin include nausea, vomiting, stomach pain, diarrhoea and loss of appetite.

As metformin can stimulate fertility, if you're considering using it for PCOS and not trying to get pregnant, make sure you use suitable contraception if you're sexually active.

The National Institute for Health and Care and Excellence (NICE) has more information about the use of metformin for treating PCOS in women who are not trying to get pregnant, including a summary of the possible benefits and harms.

Letrozole is sometimes used to stimulate ovulation instead of clomifene. This medication can also be used for treating breast cancer.

Use of letrozole for fertility treatment is "off-label". This means that the medication's manufacturer has not applied for a licence for it to be used to treat PCOS.

In other words, although letrozole is licensed for treating breast cancer, it does not have a license for treating PCOS.

Doctors sometimes use an unlicensed medication if they think it's likely to be effective and the benefits of treatment outweigh any associated risks.

Find out more about unlicensed and off-label use of medications

If you're unable to get pregnant despite taking oral medications, a different type of medication called gonadotrophins may be recommended.

These are given by injection. There's a higher risk that they may overstimulate your ovaries and lead to multiple pregnancies.

Unwanted hair growth and hair loss

Medications to control excessive hair growth (hirsutism) and hair loss (alopecia) include:

• particular types of combined oral contraceptive tablets (such as co-cyprindiol, Dianette, Marvelon and Yasmin)
• cyproterone acetate
• spironolactone
• flutamide
• finasteride

These medications work by blocking the effects of "male hormones", such as testosterone, and some also suppress production of these hormones by the ovaries.

A cream called eflornithine can also be used to slow down the growth of unwanted facial hair.

This cream does not remove hair or cure unwanted facial hair, so you may wish to use it alongside a hair removal product.

Improvement may be seen 4 to 8 weeks after treatment with this medication.

But eflornithine cream is not always available on the NHS because some local NHS authorities have decided it's not effective enough to justify NHS prescription.

If you have unwanted hair growth, you may also want to remove the excess hair by using methods such as plucking, shaving, threading, creams or laser removal. 

Laser removal of facial hair may be available on the NHS in some parts of the UK.

Other symptoms

Medications can also be used to treat some of the other problems associated with PCOS, including:

• weight-loss medication, such as orlistat, if you're overweight
• cholesterol-lowering medication (statins) if you have high levels of cholesterol in your blood
• acne treatments

Surgery

A minor surgical procedure called laparoscopic ovarian drilling (LOD) may be a treatment option for fertility problems associated with PCOS that do not respond to medication.

Under general anaesthetic, your doctor will make a small cut in your lower tummy and pass a long, thin microscope called a laparoscope through into your abdomen.

The ovaries will then be surgically treated using heat or a laser 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 can restore the normal function of your ovaries.

Pregnancy risks

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

These risks are particularly high if you're obese. If you're overweight or obese, you can lower your risk by losing weight before trying for a baby.