Perimenopause is one of the most common reasons women present to an endocrinologist, yet it remains poorly understood and inconsistently managed. Symptoms are frequently dismissed, misattributed to thyroid disease or stress, or treated without an accurate understanding of the underlying hormonal shift. This article sets out what perimenopause actually is, how it is diagnosed, and how it is managed under the most current UK (NICE), Irish (HSE/ICGP) and European (European Society of Endocrinology) guidance — including two new non-hormonal treatments licensed in 2023 and 2025, and Ireland's free HRT scheme.
What Is Perimenopause?
Perimenopause is the transitional phase leading up to menopause, during which ovarian function gradually declines and oestrogen and progesterone levels fluctuate — often erratically, rather than falling in a smooth, predictable line. Menopause itself is a single point in time, defined retrospectively as the day marking 12 consecutive months without a menstrual period, with no other cause identified. Everything before that point, once cycle changes or symptoms begin, is perimenopause.
The perimenopausal transition typically lasts 4 to 8 years and most commonly begins in a woman's mid-to-late 40s, though it can start in the late 30s. The average age of natural menopause in Ireland and the UK is 51. Menopause before age 45 is termed early menopause; before age 40 it is termed premature ovarian insufficiency (POI), affecting roughly 1 in 100 women and carrying distinct long-term health implications discussed below.
The internationally recognised Stages of Reproductive Aging Workshop (STRAW+10) framework divides the transition into early and late perimenopause based on cycle length variability, followed by early and late postmenopause. Late perimenopause — marked by cycle gaps of 60 days or more — is when vasomotor symptoms (hot flushes, night sweats) are typically most intense, as oestrogen withdrawal becomes more pronounced.
Recognising the Symptoms
The hallmark early sign of perimenopause is a change in menstrual cycle pattern — cycles becoming shorter, longer, heavier, lighter, or simply less predictable. Beyond cycle changes, perimenopause can produce a wide range of symptoms, driven by fluctuating oestrogen's effects on the brain, blood vessels, bone, connective tissue and urogenital system:
- Vasomotor symptoms: hot flushes and night sweats — the most recognisable symptoms, affecting up to 80% of women during the transition
- Sleep disturbance: difficulty falling or staying asleep, often compounded by night sweats
- Mood changes: low mood, anxiety, irritability and reduced emotional resilience — new-onset or worsening depression/anxiety in the 40s should prompt consideration of perimenopause
- Cognitive symptoms: difficulty concentrating and word-finding, often described as "brain fog"
- Genitourinary symptoms: vaginal dryness, discomfort during intercourse, recurrent urinary tract infections and urinary urgency
- Musculoskeletal symptoms: joint aches and muscle pain, increasingly recognised as an oestrogen-related symptom
- Reduced libido: a combination of hormonal, physical and psychological factors
- Skin and hair changes: reduced skin elasticity, dryness, and hair thinning
Symptom severity varies enormously between women — some pass through perimenopause with minimal disruption, while others experience severe, function-limiting symptoms for years.
Diagnosis: What the Guidelines Actually Say
One of the most consistent messages across NICE, the European Society of Endocrinology (ESE) and Irish guidance is that perimenopause is a clinical diagnosis in the majority of women — hormone blood testing is usually unnecessary and can be misleading.
| Age | Recommended Approach |
|---|---|
| Over 45 | Diagnose on symptoms and menstrual history alone. FSH testing is not required and is discouraged, as levels fluctuate too widely during perimenopause to be reliable. |
| 40–45 with atypical symptoms | FSH may be measured, ideally on day 2–5 of the cycle, or at any point after 40+ days without a period if cycles are very irregular. |
| Under 40 | Biochemical confirmation of premature ovarian insufficiency is required: FSH >25 IU/L on two occasions, 4–6 weeks apart. |
Before attributing symptoms to perimenopause, other explanations should be actively excluded, particularly in women under 45 or with atypical features: thyroid dysfunction (TSH), hyperprolactinaemia, PCOS, and functional hypothalamic amenorrhoea (often related to low energy availability, excessive exercise or significant weight loss). This is a genuinely useful check for an endocrinologist to perform, since thyroid disease in particular produces a very similar symptom picture — fatigue, mood change, cycle disturbance, temperature intolerance — and is easily missed if perimenopause is assumed by default.
Irish Guidance: The ICGP Guide and the Free HRT Scheme
Ireland does not yet have a single comprehensive national clinical guideline for menopause management in the way the UK has NICE NG23, but two developments have substantially improved the landscape for Irish patients.
The ICGP Quick Reference Guide
The Irish College of General Practitioners (ICGP), supported by the Women's Health Fund, has published a Quick Reference Guide on the Diagnosis and Management of Menopause in General Practice, intended to standardise the initial approach to perimenopause and menopause across Irish general practice and reduce variation in care. It broadly aligns with NICE and international guidance on diagnosis, first-line HRT choice, and referral triggers for specialist input.
Free HRT Since June 2025
Since 1 June 2025, the HSE has covered the cost of the great majority of body-identical and combined HRT preparations available in Ireland. To qualify, you need a valid prescription from a GP, registered nurse or midwife, and either a Medical Card or registration for the Drugs Payment Scheme (open to anyone ordinarily resident in Ireland, with no income test). A dispensing fee of up to €5 per item may still apply at the pharmacy. This removed one of the most significant practical barriers to consistent HRT use for Irish women.
UK Guidance: NICE NG23 and the 2024–2026 Updates
NICE guideline NG23, Menopause: identification and management, remains the most detailed and widely referenced clinical guideline on this topic in these islands, and it has been substantially updated across 2024, 2025 and 2026.
| Date | What Changed |
|---|---|
| November 2024 | Major evidence update: new recommendations on cognitive behavioural therapy (CBT) for menopausal symptoms, management of genitourinary symptoms, and a more detailed evidence base on the effects of HRT on specific long-term health outcomes. |
| May 2025 | Clarified rationale sections on combined HRT and breast cancer risk, ovarian cancer risk with combined HRT, and breast cancer risk with oestrogen-only HRT — reflecting updated evidence synthesis. |
| March 2026 | Added a direct link to relevant technology appraisal guidance (including fezolinetant, TA1143) within the symptom management section for people aged 40 and over. |
| April 2026 | New and amended recommendations on unscheduled vaginal bleeding while taking systemic HRT, aligned with NICE's suspected cancer pathway (NG12) — see the safety callout below. |
Some irregular bleeding is expected in the first 3–6 months after starting or changing HRT. However, NICE's April 2026 update makes clear that unscheduled vaginal bleeding persisting beyond 6 months, or new bleeding after a period of no bleeding on HRT, should be assessed using the same urgent pathway as suspected gynaecological cancer. This does not mean cancer is likely — most causes are benign — but it should not be ignored or self-managed.
Testosterone: The BMS Position
The British Menopause Society's most recent Tool for Clinicians on testosterone in menopause (May 2026) reinforces a message that has been consistent since its original 2023 statement: testosterone is not a routine third hormone of HRT. It is licensed nowhere in the UK or Ireland specifically for female use and is prescribed off-label, reserved for persistent low sexual desire (hypoactive sexual desire disorder) once oestrogen-based HRT has been optimised and other contributing factors — relationship, psychological, medication-related — have been considered. When prescribed, dosing targets the normal female physiological range, monitored with blood testing.
The European Perspective: ESE Guideline (2025)
In October 2025, the European Society of Endocrinology (ESE) — the professional body for endocrinologists across Europe — published its own clinical practice guideline for the evaluation and management of menopause and perimenopause in the European Journal of Endocrinology. As an endocrinology-specific guideline, it is particularly relevant to how I approach perimenopause in clinic, and it aligns closely with NICE while adding endocrine-specific nuance.
Key ESE Recommendations
- Diagnosis: No FSH testing needed over 45 with typical symptoms; confirmatory FSH testing for suspected POI under 40; alternative causes (thyroid disease, hyperprolactinaemia, PCOS, functional hypothalamic amenorrhoea) should be excluded in reproductive-age women.
- Who should receive HRT: Women within 10 years of natural menopause, or under 60, with bothersome vasomotor or other climacteric symptoms. All women with POI should receive HRT regardless of whether they have symptoms, given the long-term cardiovascular and bone consequences of untreated early oestrogen deficiency.
- Formulation: Women with a uterus require combined oestrogen-progestogen therapy to protect the endometrium; women without a uterus can use oestrogen alone.
- Route: Transdermal oestrogen is preferred over oral in women with a history of venous thromboembolism, diabetes, hypertension, or migraine with aura, reflecting its more favourable clotting risk profile.
- What HRT is not for: ESE explicitly states MHT should not be used primarily for cardiovascular disease prevention, dementia prevention or treatment, or as a routine treatment for clinical depression — it should be prescribed for its licensed menopausal indications, with other benefits considered secondary.
- Bone protection: HRT prevents bone loss and reduces fracture risk, and this benefit should factor into the decision for symptomatic women under 60, particularly those with additional osteoporosis risk factors.
- Review: Treatment efficacy should be reassessed at 3 months, with dose or formulation adjusted as needed — perimenopause management is rarely a "set and forget" prescription.
The ESE guideline also explicitly frames perimenopause management as requiring a holistic approach — not hormone therapy in isolation, but attention to metabolic health, bone health, mental health and lifestyle factors alongside it. This is consistent with how perimenopause presents in practice: rarely as an isolated set of vasomotor symptoms, and much more often intertwined with weight change, mood, sleep and bone health.
Treatment Options
Hormone Replacement Therapy (HRT)
For most women without contraindications, HRT remains the most effective treatment for vasomotor symptoms and several other perimenopausal symptoms, and current UK/European guidance favours body-identical formulations as first-line:
- Oestrogen: Estradiol, usually delivered transdermally as a patch, gel or spray — preferred over oral tablets for most women because it avoids first-pass liver metabolism and carries a lower venous thromboembolism (VTE) risk.
- Progestogen (for women with a uterus): Micronised progesterone (Utrogestan) is preferred over older synthetic progestogens, with a more favourable VTE and breast cancer risk profile. It can be given cyclically (with a monthly withdrawal bleed) or continuously (aiming for no bleeding) depending on menopausal stage and preference.
- Local (vaginal) oestrogen: Low-dose vaginal oestrogen treats genitourinary symptoms directly and can be used alongside systemic HRT, or alone, and carries negligible systemic absorption — it is not subject to the same duration limits as systemic HRT and can be continued long-term.
Combined HRT is associated with a small increase in breast cancer risk that increases with duration of use; oestrogen-only HRT carries little to no increase. For most women starting HRT in their late 40s or early 50s without additional risk factors, the absolute risk increase is smaller than that associated with common lifestyle factors such as obesity or regular alcohol consumption. Transdermal oestrogen does not appear to increase VTE risk above baseline, unlike oral oestrogen. Risk should always be assessed and discussed individually, particularly for use beyond 5 years or in women with personal or family risk factors.
Non-Hormonal Options
Not everyone can or wants to use HRT. Two neurokinin receptor antagonists have been licensed specifically for moderate-to-severe vasomotor symptoms in recent years, representing the first genuinely new non-hormonal mechanism for hot flushes in decades:
| Drug | Mechanism & Status |
|---|---|
| Fezolinetant (Veozah) | NK3 receptor antagonist. Licensed by the MHRA in the UK in December 2023; recommended by NICE (TA1143) for moderate-to-severe vasomotor symptoms when HRT is unsuitable or not preferred. |
| Elinzanetant (Lynkuet) | Dual NK1/NK3 receptor antagonist. The UK MHRA was the first regulator worldwide to approve it, in July 2025; the EU followed with marketing authorisation in November 2025. It works by blocking the same overactive temperature-regulation pathway in the brain, without hormones. |
Both drugs work by blocking neurokinin B signalling in the hypothalamus, a pathway that becomes overactive as oestrogen falls and directly drives the brain's thermoregulatory hot flush response. Availability and reimbursement status in Ireland can lag behind UK and EU licensing, so confirm current access with your prescriber and pharmacy.
Other established non-hormonal options include certain SSRIs/SNRIs (venlafaxine has the best evidence base), gabapentin, clonidine, and cognitive behavioural therapy (CBT) — now specifically recommended by NICE's November 2024 update as an evidence-based option for managing menopausal symptoms, either alongside or instead of medication.
The Metabolic and Bone Health Dimension
As an endocrinologist, the symptoms I am often asked about last are frequently the ones with the greatest long-term health consequence: metabolic and skeletal changes.
Weight and Insulin Resistance
Falling and fluctuating oestrogen during perimenopause is independently associated with a shift toward central (abdominal) fat distribution, reduced insulin sensitivity, and a lower resting metabolic rate — changes that occur even without any alteration in diet or activity levels. This is why many women notice weight gain, particularly around the abdomen, during perimenopause despite no change in habits, and why generic weight-loss advice often under-delivers during this life stage. Managing this effectively means addressing insulin resistance directly, through a combination of dietary change, resistance exercise (which also protects bone and muscle mass), and, where clinically appropriate, medical therapy.
Bone Health
Oestrogen is one of the principal regulators of bone remodelling, and its decline through perimenopause and early menopause drives the fastest phase of bone loss in a woman's life — up to 20% of bone density can be lost in the first 5 to 7 years following the final menstrual period. HRT started around this time reduces fracture risk. Women with early menopause or POI face a longer cumulative period of oestrogen deficiency and should have their osteoporosis risk formally assessed, including consideration of a DEXA scan where indicated.
When to Seek Specialist Review
- You are under 40 with irregular periods or menopausal symptoms (possible premature ovarian insufficiency)
- Your symptoms remain poorly controlled despite an adequate trial of HRT
- You have a personal or strong family history that complicates the HRT risk-benefit discussion
- You have unscheduled bleeding on HRT persisting beyond 6 months, or new bleeding after a bleed-free period (seek prompt assessment — see safety note above)
- You have coexisting thyroid disease, diabetes, or metabolic concerns alongside perimenopausal symptoms
- You are considering testosterone therapy for persistent low libido after HRT optimisation
- You have osteoporosis risk factors alongside early or premature menopause
Perimenopause sits at an intersection I see constantly in endocrinology practice — hormonal, metabolic and skeletal change arriving together, often while a woman is also managing work, family and, not infrequently, a GP visit that focused on one symptom in isolation. The most common gap I see is not lack of access to HRT itself, but a lack of joined-up assessment: cycle symptoms treated without checking thyroid function, weight change attributed to lifestyle without acknowledging the genuine metabolic shift under way, or bone health left unconsidered until a fracture prompts a DEXA scan years later. My approach is to assess perimenopause as the systemic transition it is — hormonal symptoms, metabolic risk and bone health together — rather than treating it as a single prescription decision.
Frequently Asked Questions About Perimenopause
These are the questions I am asked most often by patients in clinic, answered directly and without jargon.
What is perimenopause and how is it different from menopause?
Perimenopause is the transitional years leading up to menopause, marked by fluctuating oestrogen and progesterone, irregular cycles, and symptoms such as hot flushes, night sweats, mood changes and sleep disturbance. Menopause itself is a single point in time — reached retrospectively once you have gone 12 consecutive months without a period. Perimenopause typically lasts 4–8 years and most commonly begins in the mid-to-late 40s, though it can start earlier.
What are the first signs of perimenopause?
The earliest and most consistent sign is a change in menstrual cycle pattern — cycles becoming shorter, longer, heavier, lighter or less predictable. Other early symptoms include hot flushes, night sweats, disrupted sleep, mood changes, brain fog, joint aches and reduced libido. Symptoms vary widely between women in type, severity and duration.
Do I need a blood test to diagnose perimenopause?
Usually not. Both NICE and the European Society of Endocrinology recommend diagnosing perimenopause on symptoms and cycle history alone in women over 45, without hormone blood tests, because FSH levels fluctuate too much during this transition to be reliable. FSH testing is reserved for women under 40 (to investigate premature ovarian insufficiency) or women aged 40–45 with atypical symptoms.
Is HRT safe for perimenopause?
For most women without specific contraindications (such as active breast cancer or current venous thromboembolism), HRT is considered safe and is the most effective treatment for vasomotor and many other perimenopausal symptoms when started within 10 years of menopause or before age 60. Risk is individualised — transdermal oestrogen carries a lower clot risk than oral, and micronised progesterone has a more favourable safety profile than some older synthetic progestogens. A specialist or GP will assess your personal and family history before prescribing.
What's the difference between body-identical and synthetic HRT?
Body-identical HRT uses hormones structurally identical to those your body produces — estradiol (usually as a patch, gel or spray) and micronised progesterone (Utrogestan). These are now the preferred first-line formulations under UK and European guidance because of their more favourable venous thromboembolism and breast cancer risk profile compared with older synthetic or conjugated equine oestrogens and progestogens.
Does HRT cause breast cancer?
Combined oestrogen-progestogen HRT is associated with a small increase in breast cancer risk that grows with duration of use, while oestrogen-only HRT carries little or no increase in risk. To put this in context, the absolute risk increase is smaller than the risk associated with common lifestyle factors such as obesity or regular alcohol use. This risk should be discussed individually, particularly for use beyond 5 years.
Can I get free HRT in Ireland?
Yes. Since 1 June 2025, the HSE has covered the cost of most body-identical and combined HRT preparations for anyone with a valid prescription who holds a Medical Card or is registered for the Drugs Payment Scheme — there is no income test. A dispensing fee of up to €5 per item may still apply at the pharmacy.
What if HRT isn't suitable for me — are there other options?
Yes. Non-hormonal prescription options now include fezolinetant (Veozah) and, as of 2025, elinzanetant (Lynkuet) — both neurokinin receptor antagonists licensed specifically for moderate-to-severe hot flushes when HRT is unsuitable or not preferred. SSRIs/SNRIs such as venlafaxine, cognitive behavioural therapy (CBT), and lifestyle measures are also evidence-based options.
What is fezolinetant and elinzanetant, and are they available in Ireland?
Both are non-hormonal tablets that block neurokinin B signalling in the brain's temperature-regulation centre, which becomes overactive as oestrogen falls — this reduces hot flushes and night sweats without using hormones. Fezolinetant was licensed by the MHRA in the UK in December 2023 and recommended by NICE (TA1143) for moderate-to-severe vasomotor symptoms when HRT is unsuitable. Elinzanetant (Lynkuet) is newer, receiving UK MHRA approval in July 2025 and EU marketing authorisation in November 2025. Availability and reimbursement in Ireland should be confirmed with your prescriber and pharmacy, as listing can lag behind UK/EU licensing.
Should I consider testosterone for low libido in perimenopause?
The British Menopause Society's 2026 guidance is clear that testosterone is not a routine third component of HRT. It should only be considered for persistent low sexual desire (hypoactive sexual desire disorder) after oestrogen-based HRT has been optimised and other contributing factors addressed. When used, it is prescribed off-label in the UK and Ireland, dosed to stay within the normal female physiological range, and monitored with blood tests.
How does perimenopause affect my weight and metabolism?
Falling and fluctuating oestrogen during perimenopause is associated with a shift toward central (abdominal) fat storage, reduced insulin sensitivity and a lower resting metabolic rate, independent of changes in diet or activity. This is why some women notice weight gain, particularly around the abdomen, even without changing their habits. Addressing insulin resistance directly — through diet, resistance exercise, and medical therapy where indicated — is part of a comprehensive perimenopause management plan.
Does perimenopause affect bone health?
Yes. Oestrogen protects bone density, and the accelerated oestrogen decline through perimenopause and into early menopause is associated with the fastest phase of bone loss in a woman's life — up to 20% of bone density can be lost in the first 5–7 years after the final period. HRT started around this time reduces fracture risk. Women with early or premature menopause face a longer window of bone loss and should be assessed for osteoporosis risk.
I'm under 40 and having menopause-like symptoms — what does that mean?
Menopausal symptoms or irregular cycles before age 40 raise the possibility of premature ovarian insufficiency (POI), affecting around 1 in 100 women. POI requires biochemical confirmation (elevated FSH on two occasions at least 4–6 weeks apart) and should prompt specialist referral, since it carries long-term implications for bone, cardiovascular and reproductive health. Current guidance recommends HRT for all women with POI regardless of whether they have symptoms, continued until at least the average age of natural menopause.
I've started HRT and now have unexpected bleeding — what should I do?
Some irregular bleeding is common in the first 3–6 months of starting or changing HRT and often settles on its own. However, updated 2026 NICE guidance advises that any unscheduled vaginal bleeding while on systemic HRT that persists beyond 6 months, or that starts after a period of no bleeding, should be assessed promptly using the same pathway as suspected gynaecological cancer, to rule out endometrial causes. Contact your GP or prescriber if this happens to you.
References
Primary sources cited in this article, listed in order of appearance.
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1
European Society of Endocrinology. Clinical Practice Guideline for the Evaluation and Management of Menopause and the Perimenopause. Eur J Endocrinol. 2025;193(4):G49.
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2
National Institute for Health and Care Excellence. Menopause: identification and management (NG23). Originally published November 2015; updated November 2024, May 2025, March 2026 and April 2026.
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3
National Institute for Health and Care Excellence. Fezolinetant for treating moderate to severe vasomotor symptoms associated with menopause (TA1143).
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4
Medicines and Healthcare products Regulatory Agency. MHRA approves elinzanetant to treat moderate to severe vasomotor symptoms (hot flushes) caused by menopause. GOV.UK, July 2025.
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5
British Menopause Society. Tool for Clinicians: Testosterone replacement in menopause. May 2026.
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6
Irish College of General Practitioners. Quick Reference Guide on the Diagnosis and Management of Menopause in General Practice (supported by the Women's Health Fund).
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7
Health Service Executive / Citizens Information. Free Hormone Replacement Therapy (HRT) Scheme, effective 1 June 2025.
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