What is PCOS — and what to do about it

Maybe your periods have never been predictable, or they've quietly drifted further and further apart. Maybe there's acne that no skincare routine seems to touch, or new hair growing where you don't want it, or hair thinning where you do. Maybe the weight won't budge no matter what you try, and somewhere underneath all of it is a worry you haven't said out loud: will I be able to have a baby if I want one?

And maybe — this is the part that stings most — you've raised some of this with a doctor and walked out feeling brushed off. Told to lose weight. Told it's "just stress." Told to come back if it gets worse.

If any of that sounds familiar, you are not imagining it, and you are very much not alone. What you might be describing is PCOS — polycystic ovary syndrome — one of the most common hormonal conditions in women, and one that is far better understood today than the dismissive shrug you may have received suggests. Let's walk through what it actually is, how it's diagnosed, and what genuinely helps.

What PCOS actually is

PCOS is a hormonal and metabolic condition — an endocrine condition, meaning it involves the hormone-producing system of your body. The World Health Organization estimates it affects roughly 10–13% of women of reproductive age, and — this is the staggering part — up to 70% of affected women are undiagnosed (WHO). So if it has taken years and several appointments to be taken seriously, you are in enormous company.

At its core, PCOS involves a hormonal imbalance. Many women with PCOS produce slightly higher levels of androgens — hormones like testosterone that everyone has, but which are typically higher in men (Endocrine Society). That imbalance is what links the seemingly unconnected symptoms together: the irregular cycles, the skin and hair changes, the difficulty with weight, the fertility hurdles.

The name is genuinely misleading

Here's something worth saying plainly, because it confuses almost everyone: despite the name, PCOS is not about cysts. What shows up on an ultrasound isn't a collection of true cysts at all — it's a number of small, underdeveloped follicles, the tiny sacs where eggs grow (NHS). The NIH describes them as "clumps of ovarian follicles that have stopped developing" rather than actual cysts (NICHD). They are harmless in themselves. So if you've been picturing something painful or dangerous growing inside you, you can set that fear down. The name is a holdover from how the condition looked under early ultrasound, not a description of what's wrong.

How PCOS is diagnosed

PCOS is diagnosed using what's known as the Rotterdam criteria. The internationally agreed approach — reaffirmed in the 2023 International Evidence-based Guideline, the most authoritative resource we have — is that a diagnosis requires any two of these three features (2023 Guideline, Human Reproduction; NICHD):

1. Irregular or absent ovulation — periods that are infrequent, unpredictable, or missing.
2. Signs of high androgens — either clinical signs you can see (acne, excess facial or body hair, scalp hair thinning) or biochemical signs measured in a blood test (raised testosterone).
3. Polycystic-appearing ovaries on ultrasound — that picture of many small follicles.

Two crucial points sit alongside this. First, the diagnosis is only made after excluding other causes — there are other conditions that can mimic these symptoms (thyroid problems, raised prolactin, and others), and a careful clinician rules those out first (NICE CKS). Second, because you only need two of the three features, you can have PCOS without polycystic-looking ovaries on a scan — and you can have a few harmless follicles on an ultrasound without having PCOS. The scan alone is never the whole story.

The 2023 guideline also recognises a blood test called AMH (anti-Müllerian hormone) as an alternative to ultrasound for identifying that ovarian feature in adults — though it stresses AMH should never be used as a single test to diagnose PCOS on its own (ASRM).

This is exactly the kind of conversation that goes better when you arrive prepared. If you're reading this and quietly recognising yourself, the free PCOS Self-Screen in Petal is a friendly two-minute pattern check — not a diagnosis, but a way to organise what you're noticing so you can decide whether it's worth raising with your doctor, and walk in with something concrete rather than a vague "something feels off."

The symptoms, and why they cluster together

Once you understand the hormonal picture, the scattered symptoms start to make sense as one story rather than a dozen separate problems:

• Irregular or missing periods — the most common reason women first suspect something. PCOS is the most common cause of irregular or absent ovulation worldwide (WHO).
• Excess hair (hirsutism) and acne — driven by those higher androgen levels, often on the face, chest, or back.
• Hair thinning on the scalp — the same hormonal mechanism, working in the opposite direction.
• Weight that's hard to shift — closely tied to the insulin story below.
• Difficulty conceiving — because ovulation is irregular, eggs aren't released as reliably.

Symptoms often first appear in the late teens or early twenties, though they can show up later, and they vary enormously from one woman to the next (NHS). Some women have barely any symptoms; others feel the condition shaping their daily life. There is no single "PCOS look" — and importantly, you do not have to be in a larger body to have it. Women of every size can and do have PCOS (Endocrine Society).

The insulin connection

This is the piece that ties so much of PCOS together, and it's worth understanding because it changes what helps.

Many women with PCOS have insulin resistance — their bodies don't respond as efficiently to insulin, the hormone that manages blood sugar. To compensate, the body pumps out more insulin. The NIH notes that over half of women with PCOS have insulin resistance (NICHD). And here's the knock-on effect: those higher insulin levels can drive the ovaries to produce more androgens — which feeds straight back into the irregular periods, the skin and hair changes, the difficulty with weight (NHS). It becomes a loop.

Understanding this loop is genuinely empowering, because it explains why approaches that improve insulin sensitivity — the food you eat, movement, and sometimes medication — can ripple outward and ease symptoms that seem, on the surface, to have nothing to do with blood sugar.

If you'd like to see how your own eating and hydration patterns sit against how you feel, Petal's Nutrition Hub (a Petal+ feature) lets you log food and hydration over time. It won't diagnose anything — but given how central insulin is to PCOS, having a real record of your patterns, rather than relying on memory, is a quietly useful thing to bring to your own decisions and to your doctor.

The long-term health picture — calmly

It's important to be honest about long-term health, and equally important not to frighten you. Because PCOS is linked to insulin resistance, it carries an increased risk over time of type 2 diabetes and of cardiometabolic problems such as high blood pressure and unfavourable cholesterol (WHO; NHS). The 2023 international guideline recommends that women with PCOS have their cardiovascular risk factors assessed, with things like blood pressure and blood-sugar checks built into ongoing care (ASRM).

Read that as a reason for steady, informed attention — not alarm. These are risks, not destinies. Knowing about them early is precisely what lets you and your clinician keep an eye on the right things and act long before any of it becomes a problem. Awareness here is a tool, not a verdict.

What actually helps

Here is the genuinely hopeful part. The 2023 International Evidence-based Guideline is clear about where management starts: lifestyle intervention should be recommended for all women with PCOS — a combination of physical activity, eating patterns, and behavioural strategies — either before or alongside any medication (2023 Guideline; Monash University). Notably, the guideline does not anoint one specific "PCOS diet" as superior; what matters is a sustainable pattern that works for your life, supported by things like goal-setting and self-monitoring (ASRM).

Beyond lifestyle, management is tailored to your goals, and the right options depend on what matters most to you right now:

• If your priority is regulating cycles or easing acne and excess hair, hormonal options such as the combined contraceptive pill are commonly used first-line (Endocrine Society).
• If your priority is metabolic health or blood-sugar regulation, your doctor may discuss insulin-sensitising medication (NICHD).
• If your priority is conceiving, there are specific ovulation-supporting treatments — and this is a conversation for a clinician who can match the approach to you.

We're deliberately not going to push any one drug, diet, or supplement at you here. Treatment is individual, it's a decision to make with a clinician, and the headline that matters is this: PCOS is manageable. As the WHO puts it, there's no cure, but lifestyle changes, medications, and fertility treatments can reduce symptoms, improve fertility, and protect your longer-term health (WHO).

And fertility

If the fear underneath all of this is about having children — please hear this clearly. PCOS is a leading cause of difficulty conceiving precisely because it affects ovulation (WHO). But difficulty is not impossibility. The NHS is explicit that, with treatment, the majority of women with PCOS are able to get pregnant (NHS). A PCOS diagnosis is information that helps you plan — not a door closing.

When and how to seek a diagnosis

If you see yourself in this article — irregular or missing periods, unexplained acne or hair changes, weight that resists everything, or worry about fertility — it is worth raising with a doctor. You deserve to be taken seriously, and you deserve more than "lose some weight and come back."

You'll be heard more easily if you arrive with a record. A few months of cycle dates, the symptoms you've noticed and when, and any patterns you've spotted turn a vague worry into something a clinician can work with. That's the whole reason the PCOS Self-Screen exists — to help you decide whether to book the appointment — and if you want to go further, Petal's PCOS Hub lets you track symptoms over time and plan your clinical step, so the conversation starts from evidence rather than from scratch.

You are not being difficult by wanting answers. You're being your own best advocate.

How Petal helps

• PCOS Self-Screen — free. A friendly two-minute pattern check to help you decide whether your experience is worth raising with a doctor. Not a diagnosis — a calm first step.
• PCOS Hub — Petal Pro. Track your symptoms over time, see your patterns emerge, and plan the clinical step that fits your goals.
• Nutrition Hub — Petal+. Log food and hydration and watch how your patterns play out — useful context given how central insulin is to PCOS.

This article is for information and isn't medical advice or a diagnosis. PCOS can only be diagnosed by a clinician, who will also rule out other causes. Please use it to prepare for that conversation, not to replace it.