Polycystic Ovary Syndrome (PCOS)

NICE CKS Polycystic ovary syndrome. Last revised: Mar 2025.

NICE Clinical guideline [CG156] Fertility problems: assessment and treatment. Last updated: Sep 2017.

International evidence-based guideline for the assessment and management of polycystic ovary syndrome (PCOS) 2023.

Article Last Updated:26/04/2026

The diagnosis and management sections have been restructured and refined to improve clarity and usability.

Date: 12/12/25

Note on PCOS management guideline change:

Historically, there was no standalone NICE guideline on PCOS. Instead, it was previously covered within the older NICE fertility guideline CG156 (Feb 2013)
In March 2026, NICE updated this guideline as NG257, which updates and replaces CG156. In NG257, the previous recommendations on PCOS have been removed because NICE is developing a dedicated PCOS guideline.
The dedicated NICE PCOS guideline is currently in development, with expected publication on 09 December 2026. The final scope states that NICE proposes to adapt the International Evidence-Based Guideline for the Assessment and Management of Polycystic Ovary Syndrome (2023), produced by Monash University and partners.
Therefore, until the standalone NICE PCOS guideline is published, this section is based primarily on the 2023 International Evidence-Based PCOS Guideline.

Date: 26/04/26

Background Information

Definition

PCOS is a heterogeneous endocrine disorder that appears to emerge at puberty, characterised by 1) hyperandrogenism, 2) ovulation disorder, and 3) polycystic ovarian morphology.

Cause and Pathophysiology

The exact cause is unknown, likely to be multifactorial (both genetic and environmental factors)

The primary driving event is peripheral insulin resistance and subsequent hyperinsulinaemia, which results in:

Hyperandrogenism
↑ LH secretion and disrupted LH/FSH balance

Complications

Main complications:

Pregnancy-related problems
- Infertility – PCOS is the single most common cause of infertility in young women
- Pregnancy complications (miscarriage, gestational diabetes, pregnancy-induced hypertension)
Endometrial cancer (chronic anovulation → absence of progesterone production → unopposed oestrogen effect)
CVD, metabolic syndrome, NAFLD
Obstructive sleep apnoea
Psychological disorders (mainly mood and anxiety disorders)

Diagnosis

Clinical Features

Key clinical features can be grouped as follows:

Category	Features
Disrupted LF/FSH balance	Oligomenorrhoea / amenorrhoea Subfertility / infertility
Hyperandrogenism features	Hirsutism (excessive growth of dark hair in a male pattern) Acne (typically severe and cystic) Female pattern hair loss NB that PCOS does NOT cause features of virilisation (e.g. deep voice, reduced breast size, increased muscle bulk, and clitoral hypertrophy)
Hyperinsulinaemia features	Central obesity Acanthosis nigricans

Diagnostic Criteria

PCOS can be diagnosed if at least 2 out of 3 of the following are present (Rotterdam criteria):

Category	Description
Ovulatory dysfunction	Manifested as oligomenorrhoea / amenorrhoea
Hyperandrogenism (clinical OR biochemical evidence is sufficient)	Clinical evidence: Hirsutism (alone is predictive of biochemical hyperandrogenism) Acne Female pattern hair loss
	Biochemical evidence: ↑ Total testosterone (it should only be moderately raised, if significantly raised → other causes of hyperandrogenism are more likely ↑ Free androgen index ↓ SHBG Androstenedione and DHEAS should only be measured if total testosterone is NOT elevated (both would be ↑ in PCOS) Note that ↑ LH:FSH ratio is supportive of PCOS, but no longer recommended to guide diagnosis
Supportive ultrasound findings	≥20 follicles in at least 1 ovary

NICE CKS notes that in adolescent girls, BOTH irregular menstrual cycles and hyperandrogenism are required to diagnose PCOS.

PCOS is diagnosed using the Rotterdam criteria (2 out of 3).

If both ovulatory dysfunction and hyperandrogenism are present, the diagnosis can be made without pelvic ultrasound.

Excluding Differential Diagnoses

Perform ALL the following tests to exclude other causes of oligomenorrhoea and amenorrhoea in patients with suspected PCOS:

Test	Purpose
LH and FSH	Exclude premature ovarian failure ↑ LH:FSH ratio is supportive of PCOS (but no longer recommended to guide diagnosis, but common in exams). However, note that isolated ↑ FSH suggests ovarian insufficiency
Prolactin	Hyperprolactinaemia can cause subfertility and menstrual disturbances
TSH	Hyperthyroidism and hypothyroidism can cause menstrual disturbances

Test

Purpose

LH and FSH

Exclude premature ovarian failure

↑ LH:FSH ratio is supportive of PCOS (but no longer recommended to guide diagnosis, but common in exams). However, note that isolated ↑ FSH suggests ovarian insufficiency

Prolactin

Hyperprolactinaemia can cause subfertility and menstrual disturbances

TSH

Hyperthyroidism and hypothyroidism can cause menstrual disturbances

Non-PCOS causes of hyperandrogenism (such as late-onset congenital adrenal hyperplasia, Cushing’s syndrome, or androgen-secreting tumours) are more likely if any of the following features are present:

Signs of virilisation (e.g. deep voice, reduced breast size, increased muscle bulk, and clitoral hypertrophy)
Rapidly progressing hirsutism (<1 year between hirsutism being noticed and seeking medical advice)
Significantly elevated total testosterone level (>5 nmol/L or >2x the upper limit of normal)

Management

Approach:

All patients → cardiovascular and metabolic risk management
If patient is NOT trying to conceive → focus on symptom management
If patient IS trying to conceive → focus on infertility management (as most symptom management options are not appropriate in pregnancy)

Cardiovascular and Metabolic Risk Management

Aspect	Tests / management
Encourage a healthy lifestyle	Including healthy eating and regular physical activity
Optimise weight management	Regular monitoring of BMI and waist circumference Advice on weight loss if overweight / obese Also see the Overweight and Obesity article
Smoking cessation	See the Smoking Cessation article for more information
Blood pressure	Offer routine blood pressure checks Optimise hypertension management if appropriate – see the Hypertension (Primary) article
Glycaemic status	Assess glycaemic status (fasting glucose / OGTT / HbA1c) at baseline in ALL patients 2hr OGTT is recommended in high-risk women Annual 2hr OGTT should be offered to women if ANY of the following: Impaired fasting glucose (fasting glucose 6.1-6.9 mmol/L) Impaired glucose tolerance (2h post-OGTT 7.8-11.1 mmol/L)
Lipid status	Perform fasting lipid profile at baseline in ALL patients Use QRISK3 assessment tool (see the Lipid Lowering Therapy and Cardiovascular Risk Reduction article for more information)

PCOS Symptom Management

Treatment is generally tailored to the patient’s most prominent symptoms:

PCOS symptom	Management
Menstrual disturbances (oligomenorrhoea and amenorrhoea)	1st line: COCP 2nd line (if COCP is contraindicated or not tolerated): consider metformin
Hyperandrogenism (hirsutism / acne / female pattern hair loss)	1st line COCP + cosmetic therapies (e.g. laser hair removal) 2nd line: anti-androgen medications (e.g. spironolactone, finasteride) If given, anti-androgen medications must always be prescribed with an effective form of contraception (if pregnancy is possible) as they can cause incomplete development of external genitalia in male fetuses
BMI ≥25 kg/m² (metabolic / hyperinsulinaemia feature)	1st line: consider metformin

COCP is generally considered the 1st line pharmacological treatment for PCOS patients who are NOT trying to conceive. It uniquely provides all the following benefits:

Treats hyperandrogenism (↓ ovarian androgen production, ↑ SHBG)
Regulates menstrual cycles
Provides endometrial protection
Provides effective contraception

If the patient is trying to conceive → most treatment options outlined here are inappropriate:

COCP → contraindicated
Anti-androgens → contraindicated
Acne medications → retinoids are contraindicated (both topical and oral), antibiotics apart from erythromycin are contraindicated (see the Acne Vulgaris article for more information)

The only safe medication for patients who are trying to conceive is metformin.

Infertility Management

Symptom Management

As mentioned above, most standard treatment options to manage PCOS symptoms are NOT appropriate if the patient is trying to conceive:

COCP → contraindicated
Anti-androgens → contraindicated
Acne medications → retinoids are contraindicated (both topical and oral), antibiotics apart from erythromycin are contraindicated (see the Acne Vulgaris article for more information)

The only safe medication for patients who are trying to conceive is metformin.

Interventions to Improve Fertility

Optimise preconception health and lifestyle (to be implemented prior to and alongside medical treatments):

Healthy lifestyle (healthy eating and regular physical activity)
Weight management (aim to maintain 18.5-24.9 kg/m²)
Optimise blood pressure, smoking cessation, alcohol intake, sleep, and mental / emotional health

Interventions:

1st line: ovulation induction with letrozole (aromatase inhibitor)
- Alternative: clomiphene citrate and/or metformin
2nd line: gonadotrophins OR laparoscopic ovarian surgery (ovarian drilling)
3rd line: assisted reproductive technology (IVF +/- ICSI)

For those who take clomiphene citrate:

Offer ultrasound monitoring during at least 1st cycle of treatment to ensure the lowest effective dose (due to risk of multiple pregnancy and ovarian hyperstimulation syndrome)
Do not continue treatment for >6 months

Endometrial Protection

If there is prolonged amenorrhoea (<1 period every 3 months) or abnormal vaginal bleeding → give cyclical progesterone to induce a withdrawal bleed, then refer for TVUS to assess endometrial thickness

If endometrial thickness >10mm / unusual appearance → endometrial sampling
If normal endometrium → offer treatment to prevent endometrial hyperplasia
- Cyclical progestogen (e.g. medroxyprogesterone)
- Low-dose COCP
- LNG-IUD