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Health condition

Amenorrhoea, pregnancy first, then a staged workup for the real cause.

Absent periods rarely mean nothing. A short, ordered set of questions and tests almost always finds the reason - and points to a treatment that works.

Jump to treatment
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Why trust this guide

  • 01

    Editorial team

    Written by our editorial team from the UK sources listed on each page.

  • 02

    Sourced from guidance

    Checked against NICE, RCOG, BMS and peer-reviewed sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK gynaecology and endocrinology practice, including RED-S, POI and Asherman pathways.

Key facts

Amenorrhoea at a glance.

The essentials, in plain English - what counts as absent periods, why it happens, and how UK clinicians work it up.

  • What it is

    Absent menstrual periods. Primary means no periods by age 15 with normal secondary sexual characteristics. Secondary means periods have stopped for three cycles or six months in someone who previously menstruated.

  • Rule out pregnancy

    A urine or serum beta-hCG comes first for any woman of reproductive age with absent periods, whatever the suspected cause.

  • Common causes

    Functional hypothalamic amenorrhoea, PCOS, hyperprolactinaemia, thyroid disease, premature ovarian insufficiency, uterine causes such as Asherman, and menopause where age-appropriate.

  • Contraception effect

    Depo-Provera can suppress bleeding for many months after stopping. The combined pill usually returns cycles within three months. The hormonal IUS commonly causes absent periods and this is expected.

  • Why it matters

    Sustained low oestrogen affects bone health and cardiovascular risk. Absent periods can also signal fertility, endocrine or structural disease that benefits from early diagnosis.

  • Framework

    A staged workup - pregnancy test first, then TSH, prolactin, FSH, LH and oestradiol - guides the next step of imaging or specialist referral.

Why this guide matters

A staged workup, not a scattergun of tests.

Amenorrhoea has many causes - hypothalamic, pituitary, ovarian, uterine and systemic - and each has its own pathway. The three ideas below shape everything else on this page.

  • Pregnancy comes first

    Every workup of absent periods starts with a beta-hCG. It is quick, cheap and reframes the whole pathway when positive.

  • Anatomy of the axis

    Hypothalamus, pituitary, ovaries and uterus. A short set of bloods and an ultrasound tells you which level is affected.

  • Underlying cause is the target

    Restoring energy availability, treating thyroid disease or a prolactinoma, or replacing oestrogen in POI does more than any generic fix.

How the diagnosis is made

From first missed period to a clear plan.

The steps a UK GP or gynaecologist will normally follow, in order - so you know what to expect and why each test is being done.

  1. 01

    Assessing

    Pregnancy test first

    A urine or serum beta-hCG is the first investigation for every woman of reproductive age with absent periods, before any hormonal workup.

  2. 02

    Assessing

    History and medication review

    Weight change, exercise load, stress, contraception, antipsychotics, SSRIs, opiates, PPIs, headaches, galactorrhoea, hot flushes and hirsutism all point to a cause.

  3. 03

    Assessing

    Examination

    BMI, blood pressure, secondary sexual characteristics, signs of hyperandrogenism, thyroid, visual fields and Cushingoid features guide the differential.

  4. 04

    Confirming

    Core bloods

    TSH, prolactin, FSH, LH, oestradiol - plus androgens if hyperandrogenic features and a Cushing screen if clinically indicated.

  5. 05

    Confirming

    Pelvic ultrasound

    Assesses ovarian morphology, endometrial thickness and structural causes such as Mullerian anomaly. MRI is added if Asherman or a pituitary lesion is suspected.

  6. 06

    Confirming

    Karyotype and further tests

    Karyotype for primary amenorrhoea or a young woman with raised FSH. Coeliac serology, LFTs and U&Es for systemic causes.

  7. 07

    Protecting

    DEXA and bone health

    A DEXA scan is arranged where hypoestrogenism has been present for many months, to quantify bone loss and guide treatment.

Typical timeline: first visit to a working diagnosis in a few weeks.

Symptoms

What absent periods actually look like.

The patterns of history and examination that shift the differential - and the features that mean an urgent specialist opinion.

  • No period for three cycles

    Three consecutive missed cycles, or six months without a period in someone who previously menstruated, meets the definition of secondary amenorrhoea.

  • Never menstruated by 15

    Primary amenorrhoea - no periods by age 15 with normal secondary sexual characteristics, or by 13 with none - warrants prompt assessment.

  • Hot flushes and night sweats

    Vasomotor symptoms suggest low oestrogen from menopause, premature ovarian insufficiency or long-standing hypothalamic amenorrhoea.

  • Galactorrhoea and headaches

    Milky nipple discharge, headaches or visual disturbance point to hyperprolactinaemia and a possible pituitary lesion.

  • Hirsutism and acne

    Excess terminal hair, acne or scalp thinning suggest hyperandrogenism - most often PCOS, occasionally CAH or an androgen-secreting tumour.

  • Weight and exercise pattern

    Low body weight, restrictive eating or high training volume - especially in endurance sport - point to functional hypothalamic amenorrhoea and RED-S.

  • Recent uterine procedure

    Absent periods after a D&C, endometrial ablation or intrauterine infection raise concern for Asherman syndrome and intrauterine adhesions.

  • Red flag - virilisation or rapid change

    Voice deepening, clitoromegaly or rapid virilisation needs urgent endocrine review to exclude an androgen-secreting tumour.

Treatment

How amenorrhoea is treated in the UK.

Treat the cause first - hormonal, nutritional, structural or systemic - and protect bone and fertility along the way.

  • Treat the underlying cause

    The single most important step. Correcting thyroid disease, coeliac, diabetes or hyperprolactinaemia often restores cycles without hormonal replacement.

  • Dopamine agonist for prolactinoma

    Cabergoline is first line for hyperprolactinaemia and prolactinoma, normalising prolactin and shrinking most tumours over months.

  • Nutritional rehabilitation for FHA

    Restoring energy availability, addressing weight loss, reducing exercise load and psychological support are the foundation of recovery from functional hypothalamic amenorrhoea.

  • HRT for POI

    Women with premature ovarian insufficiency need oestrogen replacement to age 51 for bone, cardiovascular and cognitive protection, alongside fertility counselling.

  • Menopause pathway and HRT

    Where amenorrhoea reflects menopause, a British Menopause Society assessment guides HRT, symptom control and long-term bone and cardiovascular health.

  • PCOS-directed management

    Cycle regulation with combined hormonal contraception or cyclical progestogen, weight and metabolic support, and fertility pathways where relevant.

  • Hysteroscopic adhesiolysis

    Asherman syndrome is treated by hysteroscopic division of adhesions, often followed by an intrauterine device or oestrogen to encourage endometrial regeneration.

  • Bone health and fertility support

    DEXA, calcium and vitamin D, HRT where hypoestrogenic, and fertility counselling with selective referral for ovulation induction or IVF.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP or gynaecologist knows your history and can tell you which parts apply to you. If in doubt, get seen.

  • NICE CKS. Amenorrhoea.

  • Royal College of Obstetricians and Gynaecologists (RCOG). Green-top guidance on premature ovarian insufficiency and reproductive endocrinology.

  • British Menopause Society (BMS). Consensus statements on menopause, POI and HRT.

  • Endocrine Society. Clinical practice guideline: Functional Hypothalamic Amenorrhoea.

Red flags

When absent periods need urgent attention.

Most amenorrhoea is managed in primary care with a gynaecology or endocrinology opinion. These are the situations that need faster action.

  • Positive pregnancy test

    A positive beta-hCG changes the pathway entirely and needs early pregnancy assessment, especially if pain or bleeding is present.

  • Rapid virilisation

    Voice change, clitoromegaly or rapid hirsutism needs urgent endocrine review to exclude an androgen-secreting ovarian or adrenal tumour.

  • Visual field loss or severe headache

    A pituitary macroadenoma can compress the optic chiasm - urgent MRI and endocrinology input are required.

  • Suspected eating disorder

    Amenorrhoea with very low BMI, purging or restrictive eating needs specialist eating disorder services alongside medical assessment.

  • Postpartum shock or heavy bleeding

    Amenorrhoea and failure to lactate after a difficult delivery raise concern for Sheehan syndrome and need urgent endocrine review.

  • Amenorrhoea after uterine surgery

    Absent periods after a D&C, ablation or infection may be Asherman syndrome and warrant hysteroscopic assessment.

  • Premature ovarian insufficiency

    Raised FSH and low oestradiol under age 40 needs confirmatory testing, karyotype where appropriate, and long-term hormone and bone care.

  • Long-standing hypoestrogenism

    Persistent low oestrogen for many months warrants DEXA scanning and a proactive bone-health plan.

  • Systemic illness or weight change

    Unexplained weight loss, night sweats, jaundice or thirst point to systemic disease - coeliac, diabetes, liver or renal disease - that needs its own workup.

Living with it

A treatable pattern, once the cause is clear.

Four things that make the biggest difference - pregnancy first, fuel and rest for the axis, bone protection and thinking about fertility ahead of time.

A quiet reminder

The body speaks in cycles for a reason.

When periods stop, it is usually a signal. Investigate early rather than wait it out.

  1. 01 First

    Rule out pregnancy

    Every workup starts with a pregnancy test. It is quick, cheap and reframes the entire pathway if positive.

  2. 02 Fuel

    Energy availability matters

    Where exercise or restricted eating drives amenorrhoea, restoring energy intake and reducing training load restores cycles more reliably than any medication.

  3. 03 Bone

    Protect the skeleton

    Long-standing low oestrogen weakens bone. Ask about DEXA, vitamin D and whether HRT or the combined pill is right for you.

  4. 04 Fertility

    Plan ahead

    Absent periods do not always mean absent fertility. If you want children now or later, ask for a fertility conversation early.

Frequently asked

Everything we get asked about amenorrhoea.

Quick answers on definitions, first tests, contraception effects, FHA, POI and bone health.

  • What counts as amenorrhoea?

    Primary amenorrhoea means no periods by age 15 with otherwise normal development, or by 13 with no secondary sexual characteristics. Secondary amenorrhoea means periods have stopped for three consecutive cycles or for six months in someone who previously menstruated. Both deserve a structured workup.

  • What is the first test?

    A pregnancy test. Urine or serum beta-hCG is the first investigation for any woman of reproductive age with absent periods, whatever the suspected cause. Only after pregnancy is excluded do the hormonal tests - TSH, prolactin, FSH, LH and oestradiol - come next.

  • Why did my periods stop after coming off contraception?

    It depends on the method. The combined pill usually allows cycles to return within about three months. Depo-Provera can suppress bleeding for many months after the last injection. The hormonal IUS commonly causes absent periods while it is in place, which is expected and not harmful. If cycles have not returned after these normal windows, a full workup is appropriate.

  • What is functional hypothalamic amenorrhoea?

    FHA is a shutdown of the hypothalamic-pituitary-ovarian axis driven by low energy availability, stress, excessive exercise or weight loss - often overlapping with RED-S in athletes. Diagnosis is one of exclusion and treatment is nutritional rehabilitation, reducing training load and psychological support rather than hormones alone.

  • What is premature ovarian insufficiency?

    POI is the loss of ovarian function before age 40, confirmed by raised FSH on two occasions and low oestradiol. It carries implications for bone, cardiovascular and cognitive health and for fertility. HRT to age 51, DEXA and fertility counselling are the mainstay of care.

  • Can absent periods affect my bones?

    Yes. Sustained low oestrogen - from FHA, POI, long-standing hyperprolactinaemia or early menopause - accelerates bone loss. A DEXA scan quantifies the effect and calcium, vitamin D and often HRT protect the skeleton over the long term.

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