What Is PCOS? Symptoms, Causes and Treatment

Polycystic ovary syndrome (PCOS) is one of the most common hormonal conditions affecting women of reproductive age in the UK, estimated to affect around 1 in 10 women. Despite its name, PCOS is far more than a gynaecological issue: it disrupts hormone balance, affects ovulation, and carries long-term implications for metabolic, cardiovascular and mental health. Understanding what PCOS is, how it is diagnosed, and what can be done to manage it is essential for anyone experiencing symptoms or seeking answers about this complex condition.

What exactly is PCOS and how does it affect the body?

PCOS is a hormonal condition causing androgen excess, insulin resistance and disrupted ovulation, with systemic risks including type 2 diabetes, cardiovascular disease and endometrial hyperplasia if anovulation is prolonged.

Polycystic ovary syndrome (PCOS) is a common hormonal condition that affects the ovaries and disrupts the normal balance of reproductive hormones in people assigned female at birth. It is one of the most prevalent endocrine disorders in women of reproductive age, estimated to affect roughly 1 in 10 women in the UK, according to the NHS.^[1][5] Despite its name, not everyone with PCOS has cysts on their ovaries; the term refers to the appearance of multiple small follicles that can be seen on ultrasound.

The condition involves an imbalance in several hormones, including elevated levels of androgens (often called "male hormones", though present in all bodies), disrupted insulin signalling, and irregular production of the hormones that control the menstrual cycle, namely luteinising hormone (LH) and follicle-stimulating hormone (FSH). This hormonal disruption interferes with the normal development and release of eggs from the ovaries, a process known as ovulation.

One important consequence of prolonged or frequent anovulation (absent ovulation) is that the womb lining (endometrium) is not shed regularly. Over time, this can lead to endometrial hyperplasia, a thickening of the womb lining that, if untreated, carries a small but recognised increased risk of endometrial (womb) cancer. This is why ensuring regular withdrawal bleeds, or monitoring the endometrium, is an important part of long-term PCOS management for people who are not ovulating regularly.

Because PCOS affects multiple body systems, its consequences extend beyond reproductive health. People with PCOS have a higher risk of developing type 2 diabetes, high blood pressure, high cholesterol, and cardiovascular disease over time.^[4][7] There is also an association with mental health difficulties, including anxiety and depression, as well as with obstructive sleep apnoea and non-alcoholic fatty liver disease.^[10] Understanding PCOS as a systemic condition, rather than purely a gynaecological one, is important for ensuring that all aspects of a person's health are monitored and supported appropriately.

What are the most common signs and symptoms of PCOS?

The most common symptoms are irregular or absent periods, excess hair growth, acne and fertility difficulties, though presentation varies widely and some people have few obvious signs.

The most common symptoms of PCOS include irregular or absent periods, excess hair growth (hirsutism), acne, and difficulty conceiving. However, PCOS presents very differently from person to person, and some individuals have few or no obvious symptoms, which can make the condition easy to overlook.

The key symptoms to be aware of include:

• Irregular periods: Cycles that are longer than 35 days, fewer than eight periods per year, or periods that stop altogether

• Excess androgen effects: Unwanted hair on the face, chest, back or abdomen; oily skin; and persistent acne, particularly along the jawline

• Polycystic ovaries: Ovaries that appear enlarged on ultrasound, with multiple small follicles surrounding the outer edge

• Weight changes: Many, though not all, people with PCOS carry extra weight, particularly around the abdomen, which can worsen hormonal imbalance

• Thinning hair or hair loss: Some people experience scalp hair thinning, sometimes referred to as female-pattern hair loss

• Fertility difficulties: Irregular ovulation is a leading cause of difficulty conceiving

• Mood changes: Anxiety, low mood and fatigue are frequently reported

• Acanthosis nigricans: Darkened, velvety patches of skin, typically in skin folds such as the neck or armpits, which can be a sign of insulin resistance

It is worth noting that symptoms such as acne or irregular periods are common in adolescence, and normal pubertal variation in cycle length can persist for up to two years after the first period. If symptoms persist beyond this or are significantly affecting quality of life, it is advisable to speak to a GP.

You should seek prompt GP review if you experience very heavy or prolonged periods, bleeding between periods, bleeding after sex, or if your periods stop for three months or more and you are not pregnant. These symptoms require timely assessment to rule out other causes, including endometrial changes associated with prolonged anovulation.

Symptoms can also fluctuate over time, particularly in relation to weight changes or hormonal shifts such as those that occur after stopping hormonal contraception.

How is PCOS diagnosed on the NHS?

PCOS is diagnosed using the Rotterdam criteria, requiring at least two of three features: irregular ovulation, elevated androgens, and polycystic ovaries on ultrasound, supported by blood tests to exclude other conditions.

PCOS is diagnosed on the NHS using the Rotterdam criteria, which require at least two of the following three features to be present: irregular or infrequent ovulation, clinical or biochemical signs of elevated androgens, and polycystic ovaries visible on ultrasound. No single test confirms PCOS on its own; diagnosis involves a combination of clinical assessment, blood tests and, in many cases, a pelvic ultrasound.

A GP will typically begin by taking a detailed history of menstrual patterns, symptoms and family history. Blood tests are used to measure hormone levels, including LH, FSH, testosterone, sex hormone-binding globulin (SHBG), and prolactin. Thyroid function tests and tests for other conditions that can mimic PCOS are usually carried out to rule out alternative diagnoses. These include 17-hydroxyprogesterone (to exclude non-classical congenital adrenal hyperplasia) and tests for hyperprolactinaemia.

Glycaemic assessment is an important part of the workup. Fasting glucose or HbA1c may be used to screen for type 2 diabetes or impaired glucose regulation. In higher-risk groups, such as those with a raised BMI or South Asian ethnicity, an oral glucose tolerance test (OGTT) may be preferred, as it is more sensitive for detecting impaired glucose tolerance.^[12][4] Glycaemic status should be reassessed periodically, particularly if risk factors change.

A pelvic ultrasound, often performed transvaginally for the clearest images, can identify the characteristic appearance of polycystic ovaries. However, NICE guidance notes that ultrasound findings alone are not sufficient for diagnosis, and the presence of polycystic-appearing ovaries on scan is common in people without PCOS. Importantly, in adolescents within approximately two years of their first period, ultrasound morphology is not recommended as a diagnostic criterion, as polycystic-appearing ovaries are common during normal puberty.^[15][16] In younger people, diagnosis should rely on persistent features of ovulatory dysfunction and hyperandrogenism rather than ultrasound appearances.

Diagnosis can sometimes take time, as symptoms overlap with other conditions. If a GP suspects PCOS, they may refer to a gynaecologist or endocrinologist for further assessment. People who are concerned about their symptoms should not hesitate to request a review, as early diagnosis supports better long-term health management.

What causes PCOS and who is most likely to get it?

PCOS results from a combination of genetic predisposition and insulin resistance; risk is higher in those with a family history of PCOS or type 2 diabetes, those who are overweight, and people of South Asian heritage.

The exact cause of PCOS is not fully understood, but the condition is thought to result from a combination of genetic and environmental factors that disrupt normal hormonal regulation. Insulin resistance plays a central role in many cases: when cells do not respond effectively to insulin, the pancreas produces more of it, and elevated insulin levels stimulate the ovaries to produce excess androgens. This androgen excess then interferes with follicle development and ovulation.

Genetics are strongly implicated. PCOS tends to run in families, and people with a mother or sister who has the condition are at increased risk. Research suggests that multiple genes are involved rather than a single inherited mutation, which helps explain the wide variation in how PCOS presents.

Certain groups appear to be at higher risk:

• People with a family history of PCOS or type 2 diabetes

• Those who are overweight or obese, as excess body fat, particularly visceral fat, worsens insulin resistance and androgen excess

• People of South Asian heritage, who have a well-documented higher prevalence of insulin resistance and type 2 diabetes, which can worsen PCOS features; evidence for elevated risk in other ethnic groups, including Black African and Middle Eastern populations, is recognised in some guidelines but is less consistently quantified in UK-specific data^[21][22]

• Adolescents and women of reproductive age, as PCOS most commonly becomes apparent during the teens and twenties

It is important to emphasise that PCOS is not caused by anything a person has done. Lifestyle factors such as diet and physical activity can influence the severity of symptoms, but they do not cause the underlying condition. Understanding the contributing factors helps guide both treatment choices and long-term health monitoring.

What treatments and lifestyle changes can help manage PCOS?

PCOS is managed through lifestyle changes, endometrial protection, and medications such as the combined pill, metformin or ovulation-induction agents, tailored to the individual's symptoms and fertility goals.

PCOS cannot be cured, but its symptoms can be effectively managed through a combination of lifestyle changes, medications and, where needed, specialist support. Treatment is tailored to the individual's most troublesome symptoms and whether they are trying to conceive.

Lifestyle changes are considered a first-line approach by NICE, particularly for people who are overweight. Even a modest reduction in body weight of 5 to 10 per cent can meaningfully improve hormonal balance, restore more regular ovulation and reduce androgen-related symptoms.^[4][8] A balanced diet that supports stable blood glucose levels, combined with regular physical activity, is recommended.

Endometrial protection is an important consideration for people with infrequent or absent periods who are not trying to conceive. Prolonged anovulation means the womb lining is not shed regularly, which increases the risk of endometrial hyperplasia. UK guidance recommends inducing a withdrawal bleed at least every three to four months, typically using combined hormonal contraception or a course of cyclical progestogen. A GP or specialist can advise on the most appropriate approach.

Medications used in PCOS management include:

• Combined oral contraceptive pill: Regulates periods, reduces androgen levels, and improves acne and hirsutism in those not trying to conceive; also provides endometrial protection

• Metformin: An insulin-sensitising medicine that can improve metabolic features of PCOS and, in some cases, support more regular ovulation. Metformin is used off-label for PCOS in the UK. UK guidance (NICE CKS) suggests considering it particularly where there are metabolic features such as impaired glucose regulation, or where the combined pill is unsuitable or contraindicated. The decision to use metformin should be made on an individual basis with a prescriber.

• Letrozole or clomifene: Used to stimulate ovulation in those trying to conceive, under specialist supervision. Letrozole is commonly recommended as first-line treatment for ovulation induction in PCOS in current UK fertility guidance, though it is used off-label for this purpose.^[17][18] Clomifene is also used and is licensed for ovulation induction.

• Eflornithine cream: A topical option for managing unwanted facial hair; laser or light-based hair reduction therapies are also available. Eflornithine must not be used during pregnancy or breastfeeding; a prescriber can advise on suitability.

• Spironolactone: Sometimes used off-label to reduce androgen effects such as hirsutism and acne. Because spironolactone can harm a male fetus, effective contraception is essential throughout treatment and for a period after stopping.^[20] It is not suitable for use in pregnancy. Specialist supervision is required, and monitoring of potassium levels may be needed in some patients.

People trying to conceive who have not done so after 12 months of regular unprotected intercourse (or after 6 months if aged 36 or over, or sooner if there are additional concerns) should be referred for fertility assessment.^[17] Those with anovulation or amenorrhoea may be referred earlier.

Mental health support is an important but sometimes overlooked aspect of PCOS care. Referral to a counsellor or psychologist may be appropriate for those experiencing anxiety or depression.

People with PCOS should have regular reviews with their GP to monitor blood pressure, blood glucose and cholesterol, given the long-term cardiovascular and metabolic risks associated with the condition. If you experience any unexpected or troublesome effects from a medicine prescribed for PCOS, you can report this to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk.

Bolt Pharmacy is a GPhC-registered UK online pharmacy offering online consultations, with prescriber review and pharmacist support, and may be one option for people exploring how to access ongoing care for conditions such as PCOS.

Scientific References

1. Polycystic ovary syndrome (PCOS).
2. Polycystic ovary syndrome: metformin in women not trying to conceive (ESUOM6).
3. NICE PCOS/PMOS guideline consultation document.
4. Polycystic ovary syndrome – Treatment summaries.
5. Rising Incidence, Health Resource Utilization, and Costs of Polycystic Ovary Syndrome.
6. Screening for endometrial hyperplasia and endometrial cancer in premenopausal women with PCOS.
7. Type 2 diabetes and cardiovascular disease in polycystic ovary syndrome.
8. Lifestyle interventions for cardiometabolic health in women with PCOS: a systematic review and network meta-analysis.
9. Association of PCOS with metabolic syndrome and its components in adolescents: a systematic review and meta-analysis.
10. Nonalcoholic fatty liver disease and obstructive sleep apnea in PCOS.
11. Revised 2003 consensus on diagnostic criteria and long-term health risks related to polycystic ovary syndrome (Rotterdam criteria).
12. Screening for dysglycaemia by oral glucose tolerance test in women with PCOS.
13. Insulin signaling in PCOS/PMOS: molecular insights and clinical implications.
14. Physical activity, sedentary behavior, and metabolic-reproductive health in women with PMOS (PCOS): a narrative review.
15. PCOS in Adolescents – Ongoing Riddles in Diagnosis and Treatment.
16. Criteria for Diagnosis of Polycystic Ovary Syndrome during Adolescence: Literature Review.
17. Treatment for infertility.
18. Phenotype-specific efficacy of letrozole versus clomiphene citrate in PCOS: a prospective cohort study.
19. Comparative Outcomes of Letrozole Versus Clomiphene Citrate for Ovulation Induction in PCOS: Systematic Review and Meta-Analysis.
20. Medicines with teratogenic potential: what is effective contraception and how often is pregnancy testing needed?.
21. Clinical manifestations and insulin resistance in South Asian women with PCOS in the UK.
22. Phenotype and genotype of polycystic ovary syndrome in Asia: Ethnic differences.
23. Comparison of live birth rates between calorie-restricted diet and metformin prior to ovulation induction in women with PCOS: a protocol for a multicenter RCT.

Frequently Asked Questions