What is PCOS?

What is PCOS? The three features providers look for

A diagnosis rests on three features: signs of high androgens (such as acne, extra hair growth or raised testosterone on a blood test), irregular or absent periods, and polycystic ovaries on ultrasound. The WHO describes a diagnosis as needing at least two of them, once other causes have been excluded.

Ovarian cysts are not required, so the name can be misleading. The ultrasound is one piece of the picture rather than the deciding test, and 'polycystic' names one possible feature, not the whole condition.

Where the assessment starts depends on where you live. In the US, a primary care provider or OB-GYN is a good place to start. In the UK, the NHS describes a GP referral, blood tests and an ovary ultrasound, and it offers the scan only to people over 18.

If changing cycles are the main thing you have noticed, our guide to irregular periods covers the other reasons cycles vary.

What does the evidence say about PCOS?

The evidence shows that PCOS is common and often goes unnamed for years. The World Health Organization estimates that 10–13% of women of reproductive age have it, which sits close to the figure in the International PCOS Guideline, 2023.

The WHO also estimates that up to 70% of women with PCOS worldwide do not know they have it, so wondering whether your symptoms add up is a normal place to be.

Because any two of the three features are enough, one woman may mostly notice her cycles, another her skin or hair, another questions about conceiving. Each starting point shapes which options feel most relevant.

PCOS also reaches beyond the menstrual cycle. Blood sugar is the most specific link: the CDC reports that more than half of women with PCOS develop type 2 diabetes by age 40. That figure describes women as a group, not what will happen to you, and it is why a blood sugar test is the check most worth asking about.

The CDC also links PCOS with gestational diabetes, high blood pressure, abnormal cholesterol, heart disease, stroke and sleep apnea. A routine visit can cover much of this: a blood pressure reading, a cholesterol test, a glucose check in pregnancy, and a mention of how you are sleeping.

PCOS treatment and checks: how much, how often?

Treatment eases the features of PCOS rather than removing the condition, so it is matched to what matters most to you: cycles, skin, hair, fertility, or several at once.

For cycles, acne and hair, the WHO lists combined oral birth control pills (the combined contraceptive pill in the UK). Hormonal contraception is safe for most women and can help heavy or painful periods as well as PCOS symptoms. The combined pill slightly raises blood clot risk, so it is not suitable for smokers over 35 or for anyone who has migraine with aura.

For hair growth or acne, the WHO also lists androgen receptor blockers, which dampen the effect of androgens. Lifestyle change, meaning everyday habits such as food and movement, sits alongside both, and the aim is strength and how you feel.

If pregnancy is the goal, the WHO lists medicines that stimulate ovulation, surgery, or IVF.

In the UK, the NHS names more of the specifics: the pill or an IUS (hormonal coil) for periods, clomifene to encourage ovulation, spironolactone or eflornithine for hair, metformin, and laparoscopic ovarian drilling, a minor surgical procedure used for fertility problems.

On checks, the CDC suggests asking about diabetes testing. The usual test is HbA1c, called A1C in the US, and a result under 5.7% (42 mmol/mol, the unit used in the UK) is the level to look for. As for how often: every 1–3 years after gestational diabetes, and otherwise whenever you are at risk, which PCOS counts toward.

What have the studies shown about PCOS, and what is still unclear?

Studies have shown how common PCOS is, which features define it and which health conditions it is linked to. They have not yet shown a single cause: NICHD describes possible genetic subtypes of PCOS, an area that is still developing.

The prevalence and undiagnosed figures are estimates rather than head counts, and they differ a little between sources, so they are best read as a general picture.

Treatment lists differ by source too. The WHO and NHS lists overlap without matching exactly, so what you are offered may depend on where you live.

Next steps

A good place to start is a few notes: your recent period dates and anything you have noticed in your skin, hair, mood or sleep. Those can go with you to a primary care provider (a GP in the UK), along with one thing worth settling beforehand: which matters most to you right now, whether that is cycles, skin, hair or fertility. If your symptoms are getting worse, or you have any bleeding 12 months or more after your last period, it's worth seeing a doctor promptly. From there, the pace and the priorities are yours to set: not one size fits all.