Polycystic ovary syndrome (PCOS): causes, symptoms and modern treatment

Author photo
Zappelphilipp Marx•
Ultrasound scan of the ovaries for suspected PCOS

Irregular cycles, persistent acne, increased body hair, weight gain and a desire to have children that just won’t get going: all of these can be caused by polycystic ovary syndrome (PCOS). It is one of the most common hormonal disorders in people of reproductive age worldwide and a major cause of cycle problems and anovulatory infertility. This guide explains clearly what PCOS is, how to recognise common signs, how the diagnosis is made according to current guidelines and which treatment components are considered useful today.

What is PCOS? More than just “cysts on the ovaries”

PCOS is not a single symptom but a syndrome. It describes a recurring pattern of hormonal and metabolic features that can look slightly different in each person. Typical is a combination of:

  • elevated androgens such as testosterone or visible signs of androgen excess like hirsutism and acne
  • disturbances of ovulation and the cycle with infrequent or absent bleeding
  • many small, immature follicles in the ovaries that appear like cysts on ultrasound

It is important to clarify: these follicles are usually not “true” cysts but developing follicles that do not mature to ovulation. PCOS is therefore a chronic dysfunction of hormonal regulation and metabolism, not an irreversible defect of the ovaries.

How common is PCOS worldwide?

Large reviews and international organisations estimate that around 8 to 13 per cent of people with ovaries of reproductive age meet the criteria for PCOS, depending on the definition and the population studied. Many affected people are diagnosed late because cycle irregularities, acne or body hair are often dismissed as “normal” for a long time or attention focuses only on contraception.

Current fact sheets from the World Health Organization, for example the WHO PCOS fact sheet, and international guidelines emphasise that PCOS affects more than fertility: it can affect the whole body, from blood sugar and blood pressure to cardiovascular risk and mental health.

Recognising typical PCOS symptoms early

PCOS usually appears in late puberty or young adulthood, but sometimes only becomes apparent when trying to conceive. Common PCOS symptoms include:

  • irregular menstruation, cycles over 35 days or absence of periods
  • very heavy or very light bleeding without an obvious cause
  • increased hair growth on the face, chin, chest, abdomen or back
  • persistent acne or very oily skin beyond adolescence
  • thinning of scalp hair or hair loss at the forehead or crown
  • weight gain, especially central abdominal weight, often despite unchanged eating habits
  • fatigue, cravings and strong daily fluctuations in energy levels
  • difficulty becoming pregnant because ovulation is absent or hard to predict

No one shows all the features. Even single signs, such as cycles that are regularly longer than 35 days or pronounced hirsutism, are a clear reason to discuss PCOS with a healthcare professional.

Causes and mechanisms – why PCOS develops

The exact cause of PCOS is still not fully understood. Research points to an interaction of genetic predisposition, hormonal feedback systems and environmental factors. Studies from major research centres describe the syndrome as a cluster of symptoms centred on hormonal features of androgen excess and insulin resistance.

  • Genetic predisposition: PCOS occurs more frequently in some families. First-degree relatives have a markedly increased risk of developing PCOS-related features.
  • Insulin resistance: Many affected people are less sensitive to insulin. The body produces more insulin, which stimulates androgen production in the ovaries and disrupts egg maturation.
  • Weight and body composition: Overweight can worsen existing insulin resistance but is not required. Many people with PCOS are lean.
  • Environment and lifestyle: Diet, stress, sleep and physical activity influence how strongly a genetic predisposition becomes apparent, but do not explain PCOS on their own.

An important take-away: PCOS is not a “punishment” for wrong choices but a biological predisposition whose effects you can influence with the right adjustments.

Diagnosis according to guidelines – Rotterdam criteria and more

PCOS is a diagnosis of exclusion. Before making the diagnosis, clinicians check whether other conditions could explain the symptoms, such as thyroid disorders, raised prolactin levels or rare genetic causes. Only when such alternatives are excluded is PCOS considered.

Many professional bodies follow three core criteria often referred to as the Rotterdam criteria:

  • infrequent or absent ovulation with irregular or missing periods
  • clinical signs of androgen excess such as hirsutism or acne, or elevated androgen levels in the blood
  • polycystic ovaries on ultrasound with many small follicles

Typically, at least two of these three features must be present to consider a diagnosis of PCOS. A large international evidence-based guideline on PCOS diagnosis and management, available through organisations such as the Royal College of Obstetricians and Gynaecologists, summarises these criteria and clear diagnostic pathways and emphasises the importance of an informative, shared discussion with the person affected.

Public health resources such as the UK National Health Service NHS and international organisations like the World Health Organization explain in accessible language how the diagnosis is made and which everyday measures can help.

There are special considerations for adolescents: puberty-related symptoms such as acne and irregular cycles are common even without PCOS. Guidelines therefore recommend being cautious with the diagnosis in this age group and often favour watchful waiting rather than labelling too early.

Long-term risks – PCOS affects the whole body

PCOS is not only a fertility issue. Without appropriate management it can increase the risk of several physical conditions:

  • impaired glucose tolerance, prediabetes and type 2 diabetes
  • high blood pressure, unfavourable blood lipids and metabolic syndrome
  • cardiovascular disease later in life
  • sleep apnoea, particularly with higher body weight
  • thickening of the uterine lining with an increased risk of endometrial cancer if periods are very infrequent or absent
  • pregnancy complications such as gestational diabetes or high blood pressure

For this reason, international guidelines recommend regular monitoring of blood pressure, blood glucose, lipids and weight, regardless of whether there is a current desire to conceive. A large review by an endocrinology society highlights the importance of viewing PCOS as a lifelong health factor, not just a problem of people in their twenties and thirties.

Diet and exercise – the foundation of every PCOS treatment

Lifestyle is the first recommendation of almost all PCOS guidelines. It does not replace medical treatment but can substantially enhance its effects. A moderate, sustained weight loss of five to ten per cent can noticeably improve cycle regularity, hormones and metabolism in people who are overweight.

  • Blood-sugar-friendly diet: Plenty of vegetables, pulses, whole grains, nuts and healthy fats help to stabilise blood glucose and insulin. Sugary drinks, sweets and highly processed snacks should be occasional.
  • Regular physical activity: At least 150 minutes of moderate aerobic exercise per week plus one to two sessions of strength training are recommended. This improves insulin sensitivity independent of weight and has positive effects on mood and sleep.
  • Stable routines: Adequate sleep, regular meals and stress-reduction strategies help buffer hormonal fluctuations.
  • Supplements: Substances such as myo-inositol or D-chiro-inositol are under active investigation. Information from the US National Institute of Child Health and Human Development on PCOS shows that they may support cycle regularity and metabolism in some people but should always be part of a comprehensive plan.

More important than the perfect regimen is that the plan fits into your daily life. Crash diets, quick fixes and rigid bans rarely deliver sustainable benefits and can worsen binge eating, weight fluctuations and frustration.

Medical treatment – which options are available

Which medicines are appropriate depends on your goals, lab results and life stage. Modern guidelines stress a stepwise approach with active involvement from you.

  • Hormonal contraception: Combined pills, patches or vaginal rings can regulate cycles and bleeding, reduce menstrual symptoms and improve acne or hirsutism. They are suitable mainly when there is no current desire to conceive.
  • Metformin: This medication improves insulin sensitivity and is often used for insulin resistance, prediabetes or increased diabetes risk. It can have beneficial effects on weight, blood glucose, androgen levels and the cycle.
  • Anti-androgens: Agents such as spironolactone or certain progestogens can reduce excess hair growth and acne. They must always be used with effective contraception as they can harm an unborn baby.
  • Ovulation induction: For those trying to conceive, international guidelines often recommend letrozole as the first-line drug to induce ovulation. Clomiphene is an alternative but is increasingly being replaced by letrozole.
  • Gonadotrophins: Hormone injections are used when oral medications are insufficient. They require close ultrasound monitoring to avoid ovarian hyperstimulation and multiple pregnancies.
  • Weight-management medications: In some countries, medications that reduce weight and improve metabolism are used for people with significant overweight. Their use should always be individualised and evidence-based within specialist teams.

Clear, patient-friendly overviews of diagnosis and treatment can be found, for example, in patient information from the American Society for Reproductive Medicine ASRM and on the PCOS pages of the US National Institute of Child Health and Human Development NICHD, which explain lifestyle, medications and fertility treatments in detail.

PCOS and trying to conceive – systematic approach

1. Optimise the basics

Before any medical fertility treatment it is worth checking the basics. A blood-sugar-friendly diet, weight loss for those who are overweight, stopping smoking, limiting alcohol and increasing physical activity improve spontaneous ovulation rates and the chances of success for any further treatment.

2. Detect ovulation

Many people with PCOS ovulate irregularly or not at all. Cycle tracking with basal body temperature charts, ovulation tests, observing cervical mucus and, if needed, ultrasound helps to better identify ovulation. At the same time, other factors such as sperm quality and fallopian tube patency should be checked.

3. Ovulation induction and insemination

If spontaneous ovulation does not occur, letrozole or clomiphene can be used to stimulate egg maturation. Depending on the situation, intrauterine insemination may also be appropriate, where processed sperm are placed directly into the uterus.

4. IVF and ICSI

If pregnancy does not occur despite ovulation induction or if additional factors are present, procedures such as in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) are considered. People with PCOS have an increased risk of ovarian hyperstimulation syndrome, so stimulation plans and timing of ovulation trigger must be planned carefully.

5. Information from reliable sources

The US National Institute of Child Health and Human Development provides dedicated pages on PCOS and fertility with detailed explanations of hormonal stimulation, ovulation induction, IUI, IVF and ICSI. Such resources are good starting points to prepare for consultations with your healthcare team.

PCOS across the life course – from puberty to the menopause

PCOS accompanies affected people for decades but not always with the same intensity. In adolescence, acne, cycle irregularities and body image are often the main issues. Later, fertility, weight, blood pressure and blood sugar become central concerns. In perimenopause hormones change again; some symptoms ease, while others such as cardiovascular risk may become more prominent.

Good PCOS management is therefore dynamic. The aim is not to follow a rigid protocol for life but to find an appropriate mix of lifestyle measures, medical treatment and psychological support for each life stage.

Mental health – PCOS is also a psychological challenge

PCOS does not end at lab results. Studies show an increased prevalence of depressive symptoms, anxiety disorders, eating disorders and body dissatisfaction. Visible changes such as acne, increased hair growth or weight gain interact with societal ideals and can strongly affect self-esteem and relationships.

It is worthwhile to consider mental health from the outset. Open conversations with family and friends, good clinician–patient communication, psychological support, nutritional counselling, exercise coaching and peer support groups can help to view PCOS not as a personal failure but as a manageable condition. A stable psychological foundation increases the chances of implementing medical and practical measures in the long term.

When should you see a doctor about suspected PCOS?

You should seek medical advice if your cycle is clearly irregular for several months, your period is absent for more than three months or you have very infrequent bleeding. Newly developed hirsutism, persistent acne, unexplained rapid weight gain, severe fatigue or an unfulfilled desire to conceive for twelve months (often six months for people in their mid-30s and over) are also warning signs.

Acute problems such as severe lower abdominal pain, sudden one-sided pain, fever, fainting or very heavy bleeding require immediate medical assessment. PCOS cannot be reliably self-diagnosed. A structured assessment with medical history, blood tests and ultrasound is the most important step to get clarity and develop an appropriate plan.

Conclusion – understand PCOS and manage it with confidence

PCOS is common, complex and still under-recognised, but today there are better data, modern guidelines and more treatment options than ever before. With a combination of blood-sugar-friendly eating, regular exercise, individually chosen medication and long-term follow-up, cycle regularity, skin, metabolism and fertility can be markedly improved for many people. It is important to take time to understand your body, use information from reliable sources and build a care team that listens to you and makes decisions together. PCOS is a chronic but manageable predisposition — the better you understand it and the more closely treatment and daily life fit you, the more control you regain over health, family planning and quality of life.

Disclaimer: Content on RattleStork is provided for general informational and educational purposes only. It does not constitute medical, legal, or other professional advice; no specific outcome is guaranteed. Use of this information is at your own risk. See our full Disclaimer.

Frequently asked questions (FAQ)

PCOS is a hormonal and metabolic predisposition in which the ovaries often do not have regular ovulation, produce more male hormones and show many small follicles on ultrasound, which can affect the cycle, fertility and the risk of certain secondary conditions.

Signs of PCOS include very irregular or absent periods, increased body hair on the face or chest and abdomen, persistent acne, unexplained weight gain, scalp hair loss or an unfulfilled desire to conceive despite a prolonged period without contraception.

PCOS is considered a lifelong predisposition; it usually does not disappear completely but can be influenced so that many symptoms decrease and risks are reduced through a combination of diet, exercise, medication and good medical support.

Yes, many affected people have a normal or low weight, because genetic and hormonal factors play a major role, so a normal body mass index does not rule out PCOS and lean people can also have cycle disturbances and metabolic risks.

Not everyone with PCOS is overweight and not every treatment starts with weight loss, but if weight is significantly increased, a moderate, sustainable weight loss of a few per cent of starting weight can markedly improve metabolism, cycle and hormone levels without extreme diets.

A predominantly plant-focused, fibre-rich diet with plenty of vegetables, pulses, whole grains, nuts and healthy fats is recommended, while sugary drinks, sweets and highly processed convenience foods should be eaten only rarely.

Regular physical activity can improve insulin sensitivity, stabilise weight and blood glucose, lift mood and positively affect the cycle and hormonal balance, which is why it is recommended as a core component of any PCOS treatment, regardless of starting weight.

Many people with PCOS conceive spontaneously or with support, because lifestyle measures, ovulation-inducing medications and, if needed, assisted reproduction techniques can significantly improve the chances of pregnancy in many cases.

Typical medications include hormonal contraception for cycle and symptom control, metformin for insulin resistance, anti-androgens for hirsutism and acne, and letrozole, clomiphene or gonadotrophins to induce ovulation when trying to conceive, each tailored to your situation.

If PCOS is left untreated for a long time, cycle disturbances and visible symptoms may persist and the risk of type 2 diabetes, high blood pressure, lipid disorders, cardiovascular disease and changes to the uterine lining can increase, so regular follow-up is advisable.

Many affected people report mood swings, depressive episodes, anxiety and distress related to body image and fertility, so it is important to take psychological burden seriously and seek help early through counselling, peer support or psychotherapy if needed.

Even though cycles and ovulation no longer occur after the menopause, the predisposition associated with PCOS persists and can influence the risk of cardiovascular disease, blood sugar problems and weight gain, so a healthy lifestyle and regular checks remain important.