PCOS is not one disease: the 4 recognised types
PCOS is not one disease, and in 2026 an international consensus renamed it polyendocrine metabolic ovarian syndrome, or PMOS, to reflect that it affects more than ovarian cysts. NHS pages and many clinic letters will still say PCOS for now, so this guide uses both terms. The clinically useful "4 types" are the four Rotterdam phenotypes: different combinations of androgen excess, ovulatory dysfunction and polycystic ovarian morphology.1
Key facts
- PCOS or PMOS is usually diagnosed when two of three features are present after excluding other causes: irregular or absent ovulation, clinical or biochemical hyperandrogenism, and polycystic ovarian morphology or raised AMH in adults.2
- The four recognised Rotterdam phenotypes are A, B, C and D, not the influencer categories "adrenal", "inflammatory", "post-pill" and "insulin-resistant".5
- Insulin resistance is common and important, but not every person with PCOS has the same metabolic risk.
- Rapidly worsening hair growth, voice deepening, clitoromegaly or very high testosterone needs urgent assessment for causes other than PCOS.
- Treatment should match the main goal: cycle protection, acne or hair symptoms, fertility, weight and metabolic risk, pain, or mental wellbeing.
Why PCOS has been renamed PMOS
The old name, polycystic ovary syndrome, is misleading. The "cysts" are actually small follicles, not dangerous ovarian cysts. Some people with PCOS do not have polycystic ovarian morphology, and some people with polycystic-looking ovaries do not have PCOS. The condition can involve androgens, ovulation, insulin resistance, body weight, pregnancy risk, sleep apnoea, mood, cardiovascular risk and long-term metabolic health.
A 2026 international consensus in The Lancet renamed PCOS as polyendocrine metabolic ovarian syndrome, or PMOS, after a global process involving clinicians, researchers and patient voices. The new name is intended to reduce confusion and stigma and to highlight endocrine and metabolic features beyond the ovary.1
That does not mean every NHS letter will change immediately. The 2023 International Evidence-based Guideline still uses PCOS, and UK NHS patient information still uses PCOS.3 During the transition, the practical question remains the same: which phenotype and risk pattern do you have?
Evidence grade: the four phenotypes are research and diagnostic categories based on Rotterdam criteria. They are useful for understanding patterns, but treatment still has to be individual.
The four recognised phenotypes
The Rotterdam framework combines three features: hyperandrogenism, ovulatory dysfunction and polycystic ovarian morphology. Hyperandrogenism can be clinical, such as hirsutism or acne, or biochemical, such as raised testosterone or free androgen index. Ovulatory dysfunction usually appears as irregular, infrequent or absent periods. Polycystic ovarian morphology means the ovary has a follicle pattern on ultrasound, or in the 2023 guideline for adults, AMH may sometimes be used as an alternative to ultrasound.2
| Phenotype | Features | What it often means clinically |
|---|---|---|
| A, classic full phenotype | Hyperandrogenism, ovulatory dysfunction and polycystic ovarian morphology. | Often the most recognisable pattern, with cycle irregularity, androgen symptoms and higher metabolic concern. |
| B, classic non-PCOM phenotype | Hyperandrogenism plus ovulatory dysfunction, without polycystic ovarian morphology. | Can still carry significant androgen and metabolic risk despite a less typical ultrasound. |
| C, ovulatory phenotype | Hyperandrogenism plus polycystic ovarian morphology, with more regular ovulation. | Periods may be regular, so acne, hair growth or biochemical androgens may drive diagnosis. |
| D, non-hyperandrogenic phenotype | Ovulatory dysfunction plus polycystic ovarian morphology, without androgen excess. | Can be milder metabolically, but other causes of irregular cycles must be considered carefully. |
A 2022 review of PCOS pathophysiology summarised these four phenotypes and explained how different diagnostic systems include or exclude them. NIH criteria mainly capture classic hyperandrogenic anovulatory phenotypes, while Rotterdam criteria include the broader four-phenotype spectrum.5 That is why two people can both be told they have PCOS and look very different.
What online "types" get right and wrong
Online PCOS content often describes insulin-resistant PCOS, adrenal PCOS, inflammatory PCOS and post-pill PCOS. These labels can be useful conversation starters, but they are not formal diagnostic categories in the main guidelines. The risk is that they can make people think they have solved the diagnosis when they have only named a possible driver.
Insulin resistance is the most important of these drivers. The 2023 guideline highlights metabolic risk factors, type 2 diabetes risk, cardiovascular risk factors, sleep apnoea and pregnancy risks as part of broader PCOS care.2 This is why a PCOS assessment should include blood pressure, weight and waist context if appropriate, glucose or HbA1c, lipids, family history and symptoms of sleep apnoea.
"Adrenal PCOS" is more complicated. Some people have higher DHEAS or adrenal androgen contribution, but marked or rapidly progressive androgen symptoms should raise concern for other causes. "Post-pill PCOS" can be misleading too. Coming off hormonal contraception can reveal an existing ovulation or androgen pattern, but the pill does not prove it caused PCOS. If periods do not return or androgen symptoms persist, assess properly.
"Inflammatory PCOS" is the vaguest label. Inflammation, gut symptoms, stress, sleep and body composition may influence symptoms, but they do not replace the diagnostic criteria. If pelvic pain, painful sex, bowel symptoms or severe period pain are present, consider endometriosis or another gynaecological condition alongside PCOS.
Tests and conditions to exclude
The NHS describes PCOS symptoms such as irregular periods, difficulty getting pregnant, excess hair growth, hair thinning, oily skin and acne, and notes that diagnosis may involve hormone blood tests and ultrasound.3 The 2023 international guideline also emphasises excluding other causes before diagnosing PCOS or PMOS.2
Common exclusions include pregnancy, thyroid disease, raised prolactin, non-classic congenital adrenal hyperplasia, hypothalamic amenorrhoea, premature ovarian insufficiency, Cushing's syndrome and androgen-secreting tumours. Which tests are needed depends on the pattern. Very high testosterone, rapid virilisation, new severe symptoms or onset outside the typical reproductive-age pattern need more urgent assessment.
Useful baseline checks often include total testosterone or calculated free androgen index, SHBG, sometimes DHEAS or androstenedione, TSH, prolactin, pregnancy test if relevant, HbA1c or fasting glucose, lipids, blood pressure, weight or waist context, and sometimes ultrasound or AMH in adults. Adolescents need different criteria because irregular cycles and multifollicular ovaries can be normal during puberty.2
Safety point: seek prompt medical advice for rapidly worsening facial or body hair, voice deepening, scalp balding with rapid onset, clitoral enlargement, pelvic mass symptoms, severe pain, very heavy bleeding, or long gaps without periods.
Treatment depends on the phenotype and goal
There is no one PCOS treatment because there is no one PCOS pattern. If the main issue is irregular or absent periods, the priority may be endometrial protection and cycle management. If the main issue is acne or hirsutism, treatment may target androgen effects. If fertility is the goal, ovulation induction may be relevant. If metabolic risk is high, lifestyle, sleep, weight-neutral metabolic support, metformin or other care may be considered.
The Endocrine Society guideline recommends diagnosing PCOS using Rotterdam criteria and screening for metabolic and reproductive issues while excluding mimicking disorders.4 The 2023 international guideline gives more current recommendations, including letrozole as first-line pharmacological ovulation induction in anovulatory infertility where no other infertility factors are present, and emphasises emotional wellbeing, quality of life and weight stigma awareness.2
Supplements should be kept proportionate. Inositol, vitamin D, omega-3, berberine, NAC and spearmint are all discussed online, but they should not replace diagnosis, cycle protection, fertility care or metabolic monitoring. If you use supplements, check interactions, pregnancy plans and duplication with prescribed medicines.
Use the health library to compare PCOS with thyroid, adrenal, pelvic pain and metabolic conditions. The insights section can help you evaluate supplement claims, and the stack builder can help organise supplement and medication questions before review.
What to ask your GP
Bring dates, not just symptoms. Track cycle length, missed periods, acne, hair growth, hair loss, weight change, sleep, fertility goals, pelvic pain, contraception history and family history of diabetes or PCOS. If you need help turning this into an appointment plan, Start here.
- Which Rotterdam features do I actually have: hyperandrogenism, ovulatory dysfunction, polycystic ovarian morphology or raised AMH?
- Which phenotype best fits my pattern, and what does that mean for metabolic risk, fertility and cycle protection?
- Have thyroid disease, raised prolactin, non-classic CAH, Cushing's, hypothalamic amenorrhoea and androgen-secreting tumours been considered where relevant?
- Do I need HbA1c or glucose testing, lipids, blood pressure review, sleep apnoea screening or liver-risk assessment?
- If I am trying to conceive, when should I be referred and what ovulation induction options are appropriate?
The four PCOS or PMOS types are not personality categories. They are ways of mapping which diagnostic features are present. Once you know that, the next step is better care: rule out mimics, protect the endometrium, treat androgen symptoms, address metabolic risk and match fertility treatment to the actual pattern.
References
- Teede HJ, Joham AE, Norman RJ, Piltonen TT, Moran LJ, Laven JS, 2026. International polycystic ovary syndrome guideline name change to polyendocrine metabolic ovarian syndrome. The Lancet. link
- Teede HJ, Tay CT, Laven J, Dokras A, Moran LJ, Piltonen TT, Costello MF, Boivin J, Redman LM, Boyle JA, Norman RJ, Mousa A, Joham AE, International PCOS Network, 2023. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Human Reproduction. link
- NHS, reviewed 2025. Polycystic ovary syndrome. link
- Legro RS, Arslanian SA, Ehrmann DA, Hoeger KM, Murad MH, Pasquali R, Welt CK, Endocrine Society, 2013. Diagnosis and treatment of polycystic ovary syndrome: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology and Metabolism. link
- Azziz R, 2022. Pathophysiology of polycystic ovary syndrome revisited: Current understanding and perspectives regarding future research. Journal of Clinical Endocrinology and Metabolism. link
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This article is educational and does not constitute medical advice, diagnosis, or a treatment recommendation. Medication uses described as “off-label” are not licensed for that purpose in the UK and should only be considered under qualified clinical supervision. Always speak to your GP, pharmacist, or a registered specialist before starting, stopping, or changing any treatment. If you have severe or alarm symptoms - unintentional weight loss, blood in your stool, difficulty swallowing, persistent vomiting, a fever, or severe pain - seek urgent medical care.