PMOS Explained: Symptoms, Causes, Diagnosis and Treatment

If you’ve recently heard the term PMOS and wondered what it means, or if you’ve had a PCOS diagnosis for years and want to understand what’s changed, this is your complete guide.

PMOS stands for polyendocrine metabolic ovarian syndrome. It’s the new name for what was previously called polycystic ovary syndrome (PCOS). The name has changed, but the condition hasn’t, and understanding it properly has never mattered more.

PMOS affects an estimated 1 in 8 women and people with ovaries worldwide, more than 3.1 million in the UK alone. Despite being one of the most common hormonal conditions, it remains widely misdiagnosed, misunderstood, and undertreated. On average, it takes two years and multiple doctor visits to get a diagnosis.

You deserve better than that. This guide covers everything: what PMOS actually is, what causes it, what it feels like, how it’s diagnosed, and what you can do about it.

Quick facts:

• PMOS is the new name for PCOS, officially adopted in May 2026, it was led by over 22,000 patients, health professionals, and advocacy groups across 195 countries
• According to the World Health Organization, the condition affects an estimated 10% to 13% of women of reproductive age.
• PMOS is a complex hormonal and metabolic condition, not simply a problem with the ovaries.
• To be diagnosed, you need to meet 2 out of 3 Rotterdam criteria: irregular periods, elevated androgens/ symptoms of high androgens, and/or evidence of polycystic ovarian morphology (via AMH blood test or ultrasound).
• There is no cure, but symptoms are highly manageable with the right combination of lifestyle, medication and support.
• Early diagnosis matters, PMOS has long-term health implications that go well beyond fertility.

What is PMOS?

P – Polyendocrine
M – Metabolic
O – Ovarian
S – Syndrome

Let’s break that down:

Polyendocrine means more than one hormone system may be involved. PMOS can affect reproductive hormones such as testosterone, LH and FSH, but it may also affect insulin, thyroid hormones, cortisol and other metabolic pathways.

Metabolic refers to the way your body processes energy, sugar and insulin. Many people with PCOS/PMOS have some degree of insulin resistance, where the body has to produce more insulin to keep blood sugar stable.

Ovarian reflects the fact that the ovaries may be affected, particularly ovulation. However, despite the old name “polycystic ovary syndrome”, you do not need to have cysts on your ovaries to have the condition.

Syndrome means it is a collection of features that can look different from person to person.

PMOS is the most common cause of irregular periods and ovulatory infertility in people with ovaries. It is also linked to an increased risk of developing insulin resistance and longer-term health risks including type 2 diabetes, cardiovascular disease, endometrial cancer, anxiety and depression.

Is PMOS the same as PCOS?

PMOS is just the newer name being used for PCOS.

For years, the condition was called polycystic ovary syndrome (PCOS), but that name has always been a bit misleading. Not everyone with PCOS has polycystic-looking ovaries, and not everyone with polycystic-looking ovaries has PCOS. The condition also affects far more than the ovaries.

The shift towards PMOS aims to better reflect the full-body nature of the condition, including its links with insulin resistance, androgen excess, metabolic health, cardiovascular risk, mental health and fertility.

That said, PCOS is still the most widely recognised search term, and most NHS, NICE and clinical guidance currently still uses PCOS. So, for now, you may see both terms used:

PCOS = the older, widely used name
PMOS = the newer, more accurate name

You can read more about why PCOS was renamed PMOS here.

What causes PMOS?

The exact cause of PMOS isn’t fully understood, but research points to a combination of genetic, hormonal and metabolic factors. It tends to run in families, and if your mother, sister or aunt has PMOS, you might be at a higher risk.

At its core, PMOS involves a dysfunction in the way the body produces and responds to hormones, particularly androgens and insulin.

Androgen excess – the ovaries (and in some cases the adrenal glands) produce higher levels of androgens than normal. Androgens are often called “male hormones,” but they play important roles in everyone’s body. In PMOS, elevated androgens disrupt the normal development of follicles in the ovaries, preventing regular ovulation.

Insulin resistance – the majority of people with PMOS have some degree of insulin resistance, meaning their cells don’t respond efficiently to insulin. This causes the pancreas to produce more insulin to compensate, and elevated insulin in turn stimulates the ovaries to produce more androgens, creating a self-reinforcing cycle.

Disrupted pituitary signalling – the hormonal signals from the brain to the ovaries are altered in PMOS. LH (luteinising hormone) is often disproportionately elevated relative to FSH (follicle-stimulating hormone), which further disrupts follicle development and ovulation.

Genetic factors – PMOS can run in families, suggesting genes play an important role. Researchers are trying to identify which genes are involved, but because it’s a complex condition, it’s not surprising that it’s not a single gene, but that many genes are involved.

What are the symptoms of PMOS?

PMOS presents differently  from person to person. Some people have many symptoms; others have very few. Some symptoms are visible; others are internal. This variability is one of the reasons it takes so long to diagnose.

Irregular or absent periods

Irregular menstrual cycles are one of the hallmark features of PMOS. Because elevated androgens interfere with regular ovulation, periods can arrive unpredictably, sometimes weeks late, sometimes skipped altogether. Some people experience very long cycles (35 days or more); others may go several months without a period.

What counts as irregular? Cycles shorter than 21 days or longer than 35 days, fewer than 8 periods per year, or periods that have no predictable pattern. If your periods have always been irregular  or if they became irregular after stopping the pill, PMOS is one of the first things worth looking into.

Hormonal acne

Hormonal acne is one of the most common and most distressing symptoms of PMOS. PMOS-related acne typically appears along the jawline, chin and lower cheeks.

It may flare around the time of a period, or it may be persistent and seemingly random. It tends to involve deeper, more inflamed spots rather than surface-level break out, and it often doesn’t respond well to standard skincare. If you’ve tried everything on your skin and still can’t get it under control, your hormones are worth investigating.

Unwanted hair growth (hirsutism)

Elevated testosterone stimulates hair growth in areas where most women don’t typically grow coarse hair, the upper lip, chin, jaw, chest, stomach and inner thighs. This is called hirsutism, and it affects a significant proportion of people with PMOS. It can range from fine, barely noticeable hair to coarser growth that feels significant and distressing.

Scalp hair thinning

While PMOS causes excess hair in some places, it can cause thinning in others. Androgenic alopecia, thinning at the temples and crown is a less-talked-about but common feature of the condition. It’s frequently underreported because people assume hair loss is unrelated to their other symptoms, or because it feels too distressing to raise with a doctor. If you’re noticing your parting widening or your hairline receding, it’s worth mentioning alongside your other symptoms.

Weight changes and difficulty managing weight

PMOS doesn’t cause weight gain directly, but insulin resistance makes it significantly harder to manage weight, particularly around the abdomen. Fat distribution in PMOS tends to be central (the stomach and waist), even in people who are not overweight overall.

Weight gain can worsen insulin resistance, which worsens androgen production, which further disrupts ovulation, a cycle that can feel very difficult to break without understanding what’s driving it.

It’s important to be clear that PMOS affects people of all body sizes. You do not need to be overweight to have PMOS, and PMOS is not caused by weight. The metabolic disruption is the cause, not the consequence. Other symptoms of insulin resistance include darkened skin, particularly near neck creases, the groin and under the breasts and skin tags in the armpits or on the neck.

Fatigue and low energy

Persistent fatigue is one of the most commonly reported but least-discussed symptoms of PMOS. It’s driven by a combination of insulin resistance (which affects how well cells use glucose for energy), disrupted sleep (common in PMOS), and the hormonal fluctuations that come with inconsistent ovulation.

If you regularly feel exhausted despite getting enough sleep, or find your energy levels unpredictable and hard to account for, it’s worth including this in any PMOS assessment.

Difficulty conceiving

PMOS is one of the most common causes of ovulatory infertility, difficulty conceiving because ovulation isn’t happening regularly or reliably. This doesn’t mean people with PMOS can’t conceive; many do, often with relatively straightforward support. But understanding PMOS early gives you the best foundation for fertility planning, whether that’s something you’re thinking about now or in the future.

Mood changes and mental health

Anxiety, depression and disordered eating are significantly more common in people with PMOS. Hormonal and metabolic disruptions have real neurological effects, oestrogen, progesterone and androgens all influence mood, and inconsistent ovulation means inconsistent levels of these hormones throughout the cycle. The experience of navigating a frequently misunderstood condition, often without adequate support, compounds this further.

How is PMOS diagnosed?

PMOS is diagnosed based on the Rotterdam Criteria. To be diagnosed with PMOS, you need to meet at least 2 out of 3 of the following criteria. You do not need all three.

Criterion 1: Irregular or absent menstrual cycles

Irregular cycles indicate that ovulation is not occurring regularly, a key feature of PMOS. “Irregular” means cycles consistently shorter than 21 days or longer than 35 days, or fewer than 8 periods per year. Absent periods (amenorrhoea) also meet this criterion.

Criterion 2: Hyperandrogenism (elevated androgens)

This means either:

• Biochemical hyperandrogenism – elevated testosterone and/or DHEAS on a blood test or
• Clinical hyperandrogenism – physical symptoms of elevated androgens: hirsutism, hormonal acne, or scalp hair thinning

The combined pill and other hormonal contraception can mask androgen excess, so if you’re currently on or have recently stopped hormonal contraception, androgen results should be interpreted in that context.

Criterion 3: Polycystic ovarian morphology (PCOM)

This refers to evidence of a high number of small antral follicles in one or both ovaries, which can be assessed in two ways:

• Ultrasound scan – a transvaginal ultrasound showing 20 or more follicles per ovary or increased ovarian volume.
• AMH blood test – an elevated AMH level is now formally accepted as an alternative marker of PCOM, meaning that for many people, a blood test alone can support this criterion without needing a transvaginal ultrasound.

You only need 2 out of 3 criteria. Professor Helena Teede, who led the international PMOS renaming process, has noted that 60% of people with PMOS meet criteria 1 and 2 alone, they don’t need their ovaries assessed at all for a diagnosis.

What else is ruled out?

Before a PMOS diagnosis is confirmed, a doctor should rule out other conditions that can cause similar symptoms, particularly thyroid disorders and high prolactin (hyperprolactinaemia), both of which can cause irregular cycles and are straightforward to test for.

You can read more about how PMOS is diagnosed here.

How is PMOS treated?

There is no one-size-fits-all treatment for PMOS cannot be cured, but symptoms can be managed, and Management depends on your symptoms, your goals, and whether you are trying to conceive.

Lifestyle

For most people with PMOS, lifestyle is the most powerful first-line intervention, particularly for managing insulin resistance, which underpins many of the condition’s wider effects.

Nutrition – a low glycaemic index (low GI) diet reduces the insulin spikes that drive androgen production. This doesn’t mean carbohydrate elimination, it means swapping refined, high-GI carbohydrates (white bread, sugary snacks, processed foods) for slower-releasing alternatives (wholegrains, legumes, vegetables). A balanced diet with adequate protein and healthy fats helps stabilise blood sugar and reduce inflammation.

Exercise – regular physical activity improves insulin sensitivity, independent of weight. Even modest increases in daily movement make a meaningful difference to metabolic health.

Stress management – chronic stress raises cortisol, which worsens insulin resistance and can further disrupt the hormonal axis. Sleep, stress reduction and nervous system support are not optional extras in PMOS management.

Weight – for people with PMOS who wish to lose weight, even a modest reduction (5–10% of body weight) has been shown to improve cycle regularity, reduce androgen levels and improve insulin sensitivity. This should be pursued through sustainable, non-restrictive means, with appropriate nutritional support, crash dieting and extreme restriction worsen the metabolic picture.

Medication

Several medications are used in PMOS management, depending on which symptoms are most prominent:

The combined oral contraceptive pill – regulates cycles, reduces androgen levels (via raised SHBG), and manages acne and hirsutism. It doesn’t treat the underlying condition, but effectively manages symptoms for many people. Not appropriate for everyone, and symptoms typically return when the pill is stopped.

Metformin – an insulin-sensitising medication that directly addresses the underlying insulin resistance of PMOS. Improves cycle regularity in many people, and is particularly useful for those who do not tolerate hormonal contraception or are trying to conceive. May also reduce the risk of long-term metabolic complications.

Anti-androgen therapy – medications such as spironolactone, cyproterone acetate and finasteride block the effect of androgens on the body’s tissues, reducing hirsutism, acne and scalp hair thinning. Usually used alongside hormonal contraception in those not trying to conceive.

Inositol – is one of the most talked-about supplements for PMOS. It may help improve how the body responds to insulin, which can support more regular ovulation, lower androgen-related symptoms and improve cycle regularity. The most studied types are myo-inositol and D-chiro-inositol, often used together in a 40:1 ratio. This ratio is commonly used because it mirrors the balance naturally found in the body, but it’s not a guaranteed fix and the evidence is still developing. It’s best used as part of a wider plan that includes nutrition, lifestyle support and medical guidance where needed.

Fertility treatment

While many people with PMOS can conceive naturally, some people may need some support. For people with PMOS who are trying to conceive, the primary approach is ovulation induction, encouraging regular ovulation through medication like letrozole or clomifene (Clomid). IVF may be recommended for those who don’t respond to oral ovulation induction, IVF is an effective option.

Mental health support

Given the prevalence of anxiety, depression and disordered eating in people with PMOS, mental health support should be considered a core part of management, not an afterthought. This might include talking therapy, CBT, specialist eating disorder support, or peer support through communities like Verity PCOS UK.

PMOS and long-term health

PMOS is not just a reproductive condition and this is perhaps the most important thing the name change helps communicate. If left unmanaged, PMOS carries meaningful long-term health risks across. Understanding these isn’t meant to be frightening, early diagnosis and proactive management significantly reduce these risks.

Type 2 diabetes

People with PMOS have a significantly higher risk of developing type 2 diabetes, driven by the underlying insulin resistance that affects the majority of people with the condition.Regular monitoring of fasting glucose and HbA1c (a marker of blood sugar control over time) is an important part of ongoing PMOS care.

Gestational diabetes

The insulin resistance associated with PMOS increases the risk of gestational diabetes during pregnancy. If you have PMOS and are pregnant or planning to conceive, your midwife or obstetrician should be aware so appropriate monitoring is in place.

Cardiovascular disease

Elevated androgens, insulin resistance, and associated changes to cholesterol and blood pressure all contribute to an increased cardiovascular risk in PMOS. This includes higher rates of high LDL (“bad”) cholesterol, low HDL (“good”) cholesterol, and high blood pressure. Regular monitoring of blood pressure and lipid profiles is recommended as part of longer-term PMOS management.

High blood pressure

Hypertension is more common in people with PMOS, linked to both the metabolic and hormonal aspects of the condition. Blood pressure should be checked regularly.

Sleep apnoea

Sleep apnoea, where breathing repeatedly stops and starts during sleep, is significantly more prevalent in people with PMOS than in the general population, independent of body weight. If you experience poor-quality sleep, loud snoring, morning headaches or significant daytime fatigue despite adequate sleep, it’s worth mentioning to your doctor.

Endometrial health

Infrequent or absent ovulation means the uterine lining isn’t shed regularly. When the endometrium builds up over time, it can thicken abnormally, this condition is called endometrial hyperplasia. Over time and if left unaddressed, this increases the risk of endometrial cancer. Regular periods, whether natural or induced, are important for endometrial protection, and this is one of the reasons managing cycle regularity in PMOS matters beyond fertility.

Mental health

As noted in the symptoms section, anxiety, depression and disordered eating are significantly more prevalent in PMOS. These are not peripheral concerns, they are part of the condition’s long-term health picture and deserve as much clinical attention as the metabolic and reproductive aspects.

When to seek help for PMOS symptoms?

If you recognise yourself in any part of this article, don’t wait. PMOS is diagnosable, manageable and worth understanding early.

See a healthcare professional if:

• Your periods are consistently irregular, very infrequent or absent
• You have persistent hormonal acne, hirsutism or scalp hair thinning
• You’ve been trying to conceive for 6 months (over 35) or 12 months (under 35) without success
• You’ve recently stopped the pill and your periods haven’t returned within 3 months
• You’ve been told you have a “high AMH” without further investigation

What hormones are tested for PMOS?

At Hertility, we help you better understand your hormones, cycles and reproductive health from home.

Our Advanced Hormone & Fertility Test can help identify patterns linked to irregular periods, ovulation issues, androgen excess, thyroid dysfunction, prolactin imbalance and ovarian reserve. Where needed, we can help guide next steps, including whether further testing, ultrasound scanning, GP follow-up or specialist referral may be appropriate.

PMOS can feel confusing, especially if your symptoms have been dismissed before. But you deserve answers that look at the full picture, not just your ovaries, not just your fertility, and not just one test result.

Take the Hertility Health Assessment to get personalised insights into your hormones, symptoms and next steps.

Once you have your results, our clinical team provides a personalised care plan, not a printout of numbers, but an actual interpretation of what your results mean for you, with clear guidance on next steps. If your results suggest PMOS, you can speak with our Private Gynaecologist, Private GP, Nutritionist for further support.

Frequently asked questions

Is PMOS the same as PCOS?

Yes. PMOS (polyendocrine metabolic ovarian syndrome) is the new name for PCOS (polycystic ovary syndrome), officially adopted following an international consensus published in The Lancet in May 2026. The condition is the same, the name has changed to better reflect its true nature as a hormonal and metabolic disorder, rather than a condition defined by ovarian cysts.

What are the main symptoms of PMOS?

The most common symptoms are irregular or absent periods, signs of elevated androgens (acne, hirsutism, scalp hair thinning), difficulty managing weight, fatigue and fertility challenges. Not everyone with PMOS will have all of these, the condition presents differently in different people.

How is PMOS diagnosed?

Diagnosis requires meeting 2 out of 3 criteria: irregular cycles, elevated androgens (on a blood test or as physical symptoms), and/or evidence of polycystic ovarian morphology on ultrasound or via AMH. Other conditions, particularly thyroid dysfunction and elevated prolactin are ruled out first.

Can you have PMOS without irregular periods?

Yes. If you have elevated androgens and polycystic ovarian morphology (on scan or via AMH), you can meet the diagnostic criteria for PMOS even with relatively regular cycles. This is one of the reasons PMOS can be missed, not everyone presents with the “classic” picture of irregular periods.

Can the pill mask PMOS?

Yes. The pill regulates bleeding and suppresses androgens, meaning irregular cycles and acne caused by PMOS can be hidden for as long as hormonal contraception is taken. When the pill is stopped, these symptoms often re-emerge, which is why stopping contraception is frequent when PMOS is first recognised.

References

1. Teede HJ et al. (2026). Polyendocrine metabolic ovarian syndrome, the new name for polycystic ovary syndrome: a multistep global consensus process. The Lancet. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(26)00717-8/fulltext
2. Rotterdam ESHRE/ASRM-Sponsored PCOS Consensus Workshop Group (2004). Revised 2003 consensus on diagnostic criteria and long-term health risks related to PCOS. Human Reproduction, 19(1), 41–47. https://pubmed.ncbi.nlm.nih.gov/14688154/
3. Teede HJ et al. (2023). International Evidence-Based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Monash University. https://www.monash.edu/medicine/sphpm/mchri/pcos/guideline
4. Balen AH et al. (2016). The management of anovulatory infertility in women with polycystic ovary syndrome. Human Reproduction, 31(7), 1438–1447. https://pubmed.ncbi.nlm.nih.gov/27150040/
5. Azziz R et al. (2016). Polycystic ovary syndrome. Nature Reviews Disease Primers, 2, 16057. https://pubmed.ncbi.nlm.nih.gov/27510637/
6. Endocrine Society (2026). Polyendocrine Metabolic Ovarian Syndrome: New name to improve diagnosis and care.https://www.endocrine.org/news-and-advocacy/news-room/2026/pcos-name-change
7. NICE (2023). Polycystic ovary syndrome: identification and management. https://www.nice.org.uk/guidance/ng239
8. Fauser BC et al. (2012). Consensus on women’s health aspects of PCOS: the Amsterdam ESHRE/ASRM-Sponsored 3rd PCOS Consensus Workshop Group. Fertility and Sterility, 97(1), 28–38. https://pubmed.ncbi.nlm.nih.gov/22153789/
9. Dokras A et al. (2011). Depression and anxiety in women with PCOS: a systematic review and meta-analysis. Journal of Clinical Endocrinology & Metabolism, 96(1), 1–12. https://pubmed.ncbi.nlm.nih.gov/20962021/
10. Ding T et al. (2016). Diagnosis and management of PCOS in the UK (2004–2014): a retrospective cohort study. BMJ Open. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4947736/