Health A to Z
Polycystic ovary syndrome (PCOS) is a common condition that affects how a woman’s ovaries work.
The three main features of PCOS are:
If you have at least two of these features you may be diagnosed with PCOS. Read more about diagnosing PCOS.
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.
If you do have signs and symptoms of PCOS, they'll usually become apparent during your late teens or early twenties. They can include:
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.
There's no cure for PCOS, but the symptoms can be treated. Speak to your GP if you think you may have the condition.
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.
If you experience symptoms of polycystic ovary syndrome (PCOS), they'll usually become apparent in your late teens or early twenties.
Not all women with PCOS will have all of the symptoms, and each symptom can vary from mild to severe. Many women only experience menstrual problems and/or are unable to conceive.
Common symptoms of PCOS include:
You should talk to your GP if you have any of these symptoms and think you may have PCOS.
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.
However, 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.
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:
Women who have had absent or very irregular periods (fewer than three or four periods a year) for many years have a higher-than-average risk of developing cancer of the womb lining (endometrial cancer).
The exact cause of polycystic ovary syndrome (PCOS) is unknown, but it's thought to be related to abnormal hormone levels.
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 cause 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, because having excess fat causes the body to produce even more insulin.
Many women with PCOS are found to have an imbalance in certain hormones, including:
The exact reason why these hormonal changes occur isn't 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.
PCOS sometimes runs in families. If any relatives, such as your mother, sister or aunt, have PCOS, then 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 haven't 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 they'll 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.
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 two of the following three criteria:
As only two of these need to be present to diagnose PCOS, you won't necessarily need to have an ultrasound scan before the condition can be confirmed.
If you're diagnosed with PCOS, you may be treated by your GP or 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 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.
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) can't be cured, but the symptoms can be managed.
Treatment options can vary because someone with PCOS may experience a range of symptoms, or just one.
The main treatment options are discussed in more detail below.
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 18.5-24.9. 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 having a healthy, balanced diet. Your diet should include plenty of fruit and vegetables, (at least five 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.
A number of medications are available to treat different symptoms associated with PCOS. These are described below.
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 three to four 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 (IUS) system, will also reduce this risk by keeping the womb lining thin, but they may not cause periods.
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 aren't successful, you may be offered injections or IVF treatment. There's an increased risk of 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 isn't licensed for treating PCOS in the UK, but because many women with PCOS have insulin resistance, it can be used "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 aren't 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 aren't trying to get pregnant, including a summary of the possible benefits and harms.
Letrozole and tamoxifen are sometimes used to stimulate ovulation instead of clomifene. These medications can also be used for treating breast cancer. Use of letrozole for fertility treatment is “off-label”. This means that the medication's manufacturer hasn't applied for a licence for it to be used to treat PCOS.
In other words, although letrozole is licensed for treating breast cancer, it doesn't 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.
Read 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 and there's a higher risk that they may overstimulate your ovaries and lead to multiple pregnancies.
An alternative to gonadotrophins is a surgical procedure called laparoscopic ovarian drilling (see below). This treatment can be as effective as using gonadotrophins, but it doesn't increase your risk of multiple pregnancies.
It's likely that a fertility specialist will check that your fallopian tubes aren't blocked before most of these treatments are used.
Read more about diagnosing PCOS.
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 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 four to eight weeks after treatment with this medication.
However, eflornithine cream isn't 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'll probably also want to use a method of physically removing the excess hair (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.
Medications can also be used to treat some of the other problems associated with PCOS, including:
A minor surgical procedure called laparoscopic ovarian drilling (LOD) may be a treatment option for fertility problems associated with PCOS.
Under general anaesthetic, your doctor will make a small cut in your lower abdomen (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.