PCOS symptoms: the signs, how it's diagnosed, and why it's now called PMOS

Polycystic ovary syndrome (PCOS) is a common, long-term hormone condition. The ovaries don't release an egg every month, and the body often makes more male-type hormones (androgens) than usual and responds less well to insulin. That mix explains most of the symptoms.

The World Health Organization estimates it affects 10 to 13% of women of reproductive age, and that up to 70% of them don't know they have it.

In May 2026 an international group of doctors and patients agreed a new name: polyendocrine metabolic ovarian syndrome (PMOS). The old name suggested the problem was cysts on the ovaries, but many women with the condition have no cysts, and it affects hormones, metabolism, skin and mood as well. The NHS and the international guideline now use PMOS; PCOS is still the name most people know.

PCOS or PCOD? "PCOD" (polycystic ovarian disease) is a term used mostly in India. Some websites describe it as a milder, separate condition, but there's no separate internationally agreed diagnosis: doctors' guidelines use PCOS, now PMOS.

Symptoms usually start in the teenage years and vary a lot between women. Some have several; some have very few.

Period and fertility signs:

• Irregular, infrequent or no periods: cycles longer than 35 days, or fewer than 8 periods a year
• Sometimes heavy or long periods when they do come
• Difficulty getting pregnant, because an egg isn't released every month

Signs of higher androgens:

• Extra hair on the face, chest, belly or back (hirsutism)
• Acne that lasts beyond the teens, or oily skin
• Thinning hair on the top of the head

Metabolic signs:

• Weight gain, especially around the belly, and finding it hard to lose
• Dark, thick, velvety patches of skin on the neck, armpits or groin (acanthosis nigricans), a sign of insulin resistance
• Tiredness, and snoring or poor sleep (sleep apnoea)

Mood: depression, anxiety, eating worries and poor body image are more common, partly because of how the symptoms make people feel.

Not everyone has cysts. The "cysts" are small follicles, eggs that didn't mature. You can have PCOS without them, and many women with follicles on a scan don't have PCOS.

The exact cause isn't known. Two things work together:

• Insulin resistance: the body needs more insulin to keep blood sugar normal, and high insulin pushes the ovaries to make more androgens.
• Higher androgens: these stop eggs from maturing and cause the hair and skin signs.

You're more likely to have PCOS if:

• your mother or sister has it, or there's type 2 diabetes in the family
• you're from a south Asian or other Asian background, according to the NHS
• you have overweight, which makes insulin resistance and symptoms stronger, although slim women can have PCOS too

PCOS isn't caused by anything you did, and it isn't a sign of poor health habits.

There's no single test. Under the international guideline (2023), adults are diagnosed when they have at least two of these three, once other causes have been ruled out:

What doctors look for	Counts as a sign when
Irregular periods or no ovulation	More than 3 years after periods started: cycles shorter than 21 or longer than 35 days, or fewer than 8 a year. Any one cycle longer than 90 days
Higher androgens	Extra hair, acne or scalp hair thinning, or a raised testosterone on a blood test
Ovaries	Many small follicles on an ultrasound scan, or a raised AMH blood test (adults only)

In teenagers, irregular periods are normal for the first years, so doctors need both irregular periods and androgen signs, and they don't use an ultrasound or AMH to diagnose PCOS.

Ruling other things out: a pregnancy test, a thyroid test (TSH) and a prolactin test are usual, sometimes with others.

After diagnosis, doctors check for the conditions PCOS can lead to: blood sugar (HbA1c or a glucose test), cholesterol, blood pressure and weight. Our thyroid symptoms guide explains how thyroid problems can look similar.

PCOS is more than a period problem. Over time it raises the risk of:

• Type 2 diabetes, and diabetes in pregnancy (gestational diabetes)
• High blood pressure and high cholesterol, and so heart disease
• Fatty liver disease
• Sleep apnoea
• Cancer of the womb lining (endometrial cancer), when periods are very infrequent for a long time, because the lining isn't shed regularly. Treatment that brings on regular bleeds protects against this.
• Pregnancy complications, such as high blood pressure and miscarriage, so pregnancies are watched more closely
• Depression and anxiety

Regular check-ups catch these early, and the healthy habits that ease symptoms also lower these risks.

There's no cure, but symptoms can be treated well, and the plan depends on what matters most to you: periods, skin and hair, weight or getting pregnant.

• Healthy eating and regular activity help everyone with PCOS, even without weight loss. If you have overweight, losing even a small amount can make periods more regular and improve insulin resistance.
• For irregular periods: the combined pill, a progestogen or a hormonal coil (IUS) can regulate bleeds and protect the womb lining.
• For unwanted hair and acne: the pill, medicines that block androgens, creams, and hair removal such as laser or electrolysis.
• Metformin, a diabetes medicine, is sometimes used for insulin resistance and weight.
• For getting pregnant: medicines that help the ovaries release an egg (such as letrozole or clomifene), and sometimes IVF or a small operation. A gynaecologist or fertility specialist guides this.
• Talking therapy and support for low mood, anxiety or eating worries.

Which medicine, and how much, is your doctor's decision. Some PCOS medicines aren't safe in pregnancy, so tell your doctor if you're trying for a baby or might be pregnant. Be wary of "PCOS cure" diets, teas and supplements sold online: ask a doctor or pharmacist before trying them.