Written and Medically reviewed by Dr Karen Joash, Consultant Obstetrician and Gynaecologist | Last reviewed: August 2026
The short answer
Polyendocrine metabolic ovarian syndrome (PMOS) is the NHS term for the condition formerly called polycystic ovary syndrome (PCOS). It can affect periods, ovulation, androgen-related symptoms, fertility, mood and metabolic health. Diagnosis requires a clinical assessment; an ultrasound alone cannot confirm or exclude it, and treatment should match the symptoms and health risks that matter to you.
Why has the name changed?
The NHS now uses polyendocrine metabolic ovarian syndrome, or PMOS, and explains that it used to be called PCOS. The new wording reflects that the condition involves hormones and metabolism and is not defined simply by ovarian cysts.
Many people, clinicians and research papers will continue to use PCOS during the transition. Using both terms on a health page helps readers find current guidance without losing access to established evidence.
Common signs and symptoms
PMOS can cause irregular periods or long gaps, difficulty conceiving because ovulation is infrequent, acne, oily skin, excess facial or body hair, scalp hair thinning, fatigue, weight gain or difficulty losing weight, and anxiety or depression.
Symptoms vary widely. Some people have insulin resistance which affects how blood sugar levels are maneged by the body. Insulin resistance s not visible and cannot be diagnosed from appearance.
How is PMOS diagnosed?
There is no single definitive test. Assessment can include menstrual history, signs or blood tests for androgen excess, glucose and metabolic risk, and sometimes ultrasound. Other causes such as thyroid disease, high prolactin or non-classic congenital adrenal hyperplasia may need exclusion.
An ultrasound is not always necessary and may be inappropriate in younger adolescents. Having polycystic-looking ovaries without the wider syndrome does not automatically mean PMOS.
What does insulin resistance mean?
Insulin helps move glucose from blood into cells. With insulin resistance, the body needs more insulin to achieve the same effect to control blood sugar levels. This can contribute to higher androgen production (testosterone) and is associated with increased risk of type 2 diabetes and cardiovascular disease.
Management may include nutrition, activity, sleep, weight-neutral risk reduction or weight management where appropriate, and medicines such as metformin in selected cases. Shame is not a treatment, and meaningful health improvements can occur without a dramatic change on the scale.
Periods, fertility and womb protection
Long gaps between periods can mean the womb lining is not shed regularly. To minimise the risk of abnormalities in the lining of the womb, it is avised that the longest gap between bleeding is 3 months. A clinician may recommend hormonal contraception, intermittent progestogen or another approach to protect the endometrium, depending on your needs.
PMOS can make ovulation less frequent, but pregnancy is still possible. If trying to conceive, treatment can support ovulation; if not, contraception remains important.
Where do inositol and supplements fit?
Inositol is widely marketed for PCOS/PMOS. Research suggests possible effects on some metabolic or reproductive measures. This is because Myo-inositol improves the body's sensitivity to insulin and sugar management is improved. It should be presented as an optional adjunct, not a cure or substitute for investigation.
Frequently asked questions
Is PMOS the same condition as PCOS?
Yes. PMOS is the current NHS term for the condition previously called PCOS.
Do you need ovarian cysts to have PMOS?
No. The syndrome is not defined by true ovarian cysts, and diagnosis considers a wider pattern.
Can someone with regular periods have PMOS?
It is possible, although irregular ovulation is common. A clinician must assess the full diagnostic picture.
A PurerVita note
PurerVita supports evidence-led choices across women's hormonal, metabolic and reproductive health. Supplements can complement food and clinical care; they do not diagnose or treat medical conditions. Seek personalised advice for symptoms, pregnancy plans, medicines or abnormal test results.
Explore PurerVita's evidence-led support for women's health.
Sources
- NHS: Polyendocrine metabolic ovarian syndrome
- NHS: Irregular periods
- NHS Scotland: PMOS, previously PCOS