PCOS, now called PMOS: a clear guide

What is PCOS (PMOS)?

A long-term condition in which the body makes more androgens (male-type hormones that women make too) and often handles insulin less well. This can upset ovulation, so periods become irregular, and it affects skin, hair, weight and long-term health. In May 2026 it was renamed PMOS to show that it involves several hormones and metabolism, not only the ovaries. Read: PCOS is now PMOS →

What are the signs?

Irregular, infrequent or missing periods; thick, dark hair on the face, chest or tummy; acne beyond the teens; thinning scalp hair; weight gain, especially around the waist; dark, velvety skin patches; difficulty getting pregnant; and low mood or anxiety. You don't need all of these, and PCOS happens at every body size. Check your signs →

What causes it?

There's no single cause. It runs in families, and insulin resistance plays a big part: when the body needs more insulin to keep blood sugar steady, the extra insulin pushes the ovaries to make more androgens. Weight gain can make symptoms stronger, but PCOS isn't caused by anything you did.

How do doctors diagnose it?

Under the 2023 international guideline, an adult is diagnosed when she has two of these three, once other causes such as thyroid problems or high prolactin (a hormone that can stop periods) have been ruled out. The three are: irregular or absent ovulation, usually seen as irregular periods; signs of higher androgens, on the skin or in a blood test; and polycystic ovaries on ultrasound or a high AMH (anti-Müllerian hormone) blood test. Teenagers need both irregular periods and signs of higher androgens, because ultrasound and the AMH test aren't reliable in the first eight years after periods start.

How is it managed?

For most women, habits come first: regular meals built on whole foods, daily movement with some strength work, enough sleep and support with stress. These help at any weight. A doctor may add medicines depending on what matters most to you, such as regular periods, skin and hair, blood sugar or pregnancy, and only a registered doctor should prescribe them.

What are the long-term risks?

PCOS raises the chance of type 2 diabetes, high cholesterol, high blood pressure, fatty liver, sleep apnoea (breathing that stops and starts during sleep), anxiety and depression, and diabetes in pregnancy. Long gaps between periods can thicken the lining of the womb, so tell your doctor if you have fewer than four periods a year. Regular checks of blood sugar, blood pressure and cholesterol catch problems early.

When should I see a doctor?

If your periods are often more than 35 days apart or have stopped for three months; if extra hair, acne or hair loss bothers you; if you've been trying to get pregnant for a year, or six months if you're 35 or over; or if you have dark velvety skin patches or a strong family history of diabetes.