What is perimenopause? Symptoms, age and how to know if you’re in it

Perimenopause is the time leading up to menopause, when your hormone levels start to change and your periods become less regular. It usually starts in your 40s and lasts several years, ending once you’ve gone 12 months without a period. During this time, many people notice symptoms such as hot flushes, sleep problems and mood changes.

Perimenopause can creep up on you. Your periods might change, you might start waking at 3am, or you might feel more anxious than usual, without realising your hormones could be behind it. This guide explains what perimenopause is, when it starts, how long it lasts, how to tell if you’re in it and what can help.

Quick facts:

• Perimenopause is the transition to menopause. It ends 12 months after your last period.
• It most often starts in your mid-40s. Menopause happens at an average age of 51 in the UK.
• Perimenopause usually lasts several years, and some symptoms can carry on after your periods stop.
• Changes to your periods are often the first sign, alongside symptoms such as hot flushes, night sweats, poor sleep and mood changes.
• If you’re 45 or over, perimenopause can usually be diagnosed from your symptoms, without a blood test.
• You can still get pregnant during perimenopause, so you’ll need contraception if you don’t want to conceive.
• Treatments, including HRT, can help, and you don’t need to wait until your periods stop to start them.

What is perimenopause?

Perimenopause is the stage before menopause, when your ovaries gradually stop working as they used to. Your hormone levels start to change, your periods become less predictable, and you may notice new physical and emotional symptoms.

What is the difference between perimenopause and menopause?

Perimenopause, menopause and postmenopause are often used interchangeably, but they mean different things:

• Perimenopause is the transition, from your first symptoms or changes to your periods up to your last period.
• Menopause is a single point in time, the moment defined as 12 consecutive months without a period. In the UK, the average age for reaching menopause is 51, though it varies.
• Postmenopause is the time after menopause, for the rest of your life.

Many people say “menopause” when they mean perimenopause. That’s understandable, but the difference matters. Perimenopause is usually when symptoms are most noticeable, and when you can still get pregnant.

What age does perimenopause start?

Perimenopause most often starts in your mid-40s, but everyone is different. Some people notice changes in their late 30s or early 40s, and others not until their late 40s. Menopause usually happens between 45 and 55.

Under 45. If your periods stop before you’re 45, this is known as early menopause.

Under 40. If your periods stop before you’re 40, it’s called premature menopause or premature ovarian insufficiency (POI). It affects around 1 in 100 women under 40. If you’re under 40 and your periods have become irregular or stopped, see your GP. POI needs proper assessment and treatment.

Your genes, lifestyle habits like smoking, some medical treatments and surgery on your ovaries can all affect when perimenopause starts. Find out more in our guide to whether you can predict when menopause will happen.

How long does perimenopause last?

Perimenopause usually lasts several years, and the length varies a lot from person to person. For most, perimenopause will last about 4 to 8 years, but it can be longer (or shorter!). It ends once you’ve gone 12 months without a period.

Symptoms don’t always stop when your periods do. Hot flushes and night sweats often carry on into postmenopause. In one large study, hot flushes and night sweats lasted more than seven years overall for around half of the women.

What causes perimenopause?

Perimenopause happens because your ovaries gradually run out of eggs and stop responding to the hormones that control your cycle.

• Oestrogen doesn’t simply fall steadily. It rises and falls unpredictably, sometimes higher than usual and sometimes lower. This variability is largely responsible for the unpredictability of perimenopausal symptoms.
• Progesterone tends to decline earlier and more steadily than oestrogen. Because progesterone is produced after ovulation, as ovulations become less frequent, progesterone production falls. This relative drop is associated with worsening PMS and sleep disruption in the early perimenopausal years.
• FSH (follicle-stimulating hormone) rises as your brain works harder to stimulate your ovaries.
• Testosterone also declines gradually through perimenopause, which can contribute to reduced libido, fatigue and changes in mood and motivation.

This is why symptoms can come and go, and why they can be so unpredictable. It’s also why a single blood test often can’t confirm perimenopause: your hormones can look normal one day and very different the next.

What are the first signs of perimenopause?

For many people, the first sign is a change to their periods. Your cycle might get shorter or longer, your periods might become heavier or lighter, or you might skip periods altogether.

Other common early signs include:

Period and cycle changes

Often the earliest and most recognisable sign of perimenopause is a change in your menstrual cycle. This can include shorter cycles (less than 21 days), longer cycles or skipped periods, heavier or lighter periods than before, spotting between periods or more intense PMS symptoms.

Hot flushes and night sweats

Hot flushes are sudden feelings of heat, usually in your face, neck and chest, which can make your skin red and flushed. They can happen at any time, often with no obvious trigger. Falling oestrogen affects the part of your brain that controls body temperature, making it more sensitive to small changes. Night sweats are hot flushes that happen while you sleep. They can be heavy enough to soak your nightwear and bedding, and wake you up.

Sleep disturbance

Poor sleep is one of the most common and most underestimated symptoms. Night sweats can wake you, but falling progesterone and changing oestrogen levels can also affect your sleep directly. Many people find they wake in the early hours and can’t get back to sleep.

Mood changes – anxiety, low mood and irritability

Changing oestrogen levels can affect the brain chemicals involved in mood, such as serotonin. You might notice:

• new or worse anxiety, sometimes a low-level sense of dread with no clear cause
• irritability, which may be worse before a period
• low mood or tearfulness that doesn’t fit your circumstances
• a feeling of not being yourself

These are some of the most often missed perimenopause symptoms, because they’re so easily put down to stress, relationship problems or a mental health condition.

Brain fog and cognitive changes

Many people notice difficulty concentrating, forgetfulness or a feeling of mental “fuzziness”, often called brain fog. Oestrogen plays a role in memory, attention and processing speed, so changing levels can affect how sharp you feel. Brain fog can be worrying, but it’s a common, recognised symptom of perimenopause, not a sign of something more serious.

Vaginal and bladder changes

Falling oestrogen can make the tissues of your vagina, vulva and urethra drier, thinner and less elastic. This is known as genitourinary syndrome of menopause (GSM), and it can cause vaginal dryness or discomfort, pain during sex, increased susceptibility to thrush or bacterial vaginosis, urinary urgency or frequency and recurrent urinary tract infections

Low libido

Changes in libido during perimenopause are driven by a combination of declining testosterone, vaginal discomfort, disrupted sleep and mood changes. 

Skin, hair and body changes

Decreased oestrogen reduces collagen production, causing skin to feel drier, thinner, and less elastic. Some people also notice increased sensitivity or new adult acne.

Falling oestrogen alongside declining progesterone and testosterone changes the hair growth cycle, and many perimenopausal people notice hair thinning at the temples or crown.

Hormone changes can affect where your body stores fat, with more weight gathering around your middle, even if your diet hasn’t changed.

Joint pain and muscle aches

Aching joints and muscles, especially stiffness in the morning, are a recognised symptom of perimenopause.

Heart palpitations

Some people notice their heart racing, fluttering or skipping a beat. These palpitations are usually harmless. But see a doctor if they happen often, come with chest pain, breathlessness or dizziness, or if you or your family have a history of heart problems.

Other commonly reported symptoms

• Headaches or worsening migraines
• Fatigue and low energy
• Dry eyes
• Tinnitus (ringing in the ears)
• Digestive changes and bloating
• Sensitive teeth, painful gums or other mouth problems
• Changes in body odour

Hertility’s Advanced Hormone and Fertility Test can help you understand what’s behind your symptoms, including checking your thyroid and other markers that can cause similar symptoms. Our clinicians interpret your results alongside your symptoms, cycle and health history.

How do I know if it’s perimenopause?

You’re likely to be in perimenopause if you’re in your 40s, your periods are changing and you’ve noticed symptoms such as hot flushes, night sweats, poor sleep or mood changes. If you’re 45 or over, a GP can usually diagnose perimenopause from your symptoms alone, without a blood test.

NICE guidance says that if you’re 45 or over and have typical symptoms, perimenopause can usually be diagnosed from your symptoms alone, without a blood test. But that doesn’t mean testing has no value. Many perimenopause symptoms, such as tiredness, brain fog, mood changes and irregular periods, can also be caused by other conditions, including thyroid problems, iron deficiency and vitamin deficiencies. Testing can help rule these out, give you a clearer picture of your overall hormone health, and make sure nothing else is being missed.

Many perimenopause symptoms can also be caused by other conditions, such as thyroid problems, iron deficiency, depression or stress. That’s why it’s worth talking to a doctor rather than assuming. Read our guide to how perimenopause is diagnosed in the UK for more on tests and diagnosis.

When and how to test your hormones for perimenopause?

Hormone tests are most useful if you’re under 45, if your symptoms are unusual, or if your doctor wants to rule out other causes. Because hormones change so much from day to day in perimenopause, results always need to be read alongside your symptoms and cycle.

• FSH. A raised FSH can suggest your ovaries are responding less well, but levels go up and down between cycles, so one result can’t confirm perimenopause. If POI is suspected in someone under 40, NICE recommends two FSH tests, four to six weeks apart.
• Oestradiol. Low or changing oestradiol can support the picture of perimenopause, but it needs to be read alongside the day of your cycle and your symptoms.
• Progesterone. A low progesterone result about a week before your period is due can show you’re not ovulating every cycle.
• Thyroid hormones (TSH and FT4). Thyroid problems can cause similar symptoms, such as tiredness, brain fog, weight changes and mood changes. They’re also more common in your 40s and 50s, so testing your thyroid helps rule them out.
• AMH. AMH declines progressively as ovarian reserve diminishes , more steadily than FSH or oestradiol. While it doesn’t diagnose perimenopause directly, it can help if you want to understand your ovarian reserve, for example if you’re thinking about your fertility.

Whatever your age, Hertility’s Advanced Hormone and Fertility Test can help you understand what’s behind your symptoms, including checking your thyroid and other markers that can cause similar symptoms. Our clinicians interpret your results alongside your symptoms, cycle and health history.

Can you get pregnant during perimenopause?

Yes. Your fertility falls during perimenopause, but you can still ovulate some months, even if your periods are irregular. So it’s still possible to get pregnant until you’ve reached menopause.

When it’s safe to stop contraception. If you don’t want to get pregnant, guidance from the Faculty of Sexual and Reproductive Healthcare is to keep using contraception until:

• you’re 55, or
• you’ve gone two years without a period, if you’re under 50, or
• you’ve gone one year without a period, if you’re 50 or over

Some hormonal contraception can stop your periods or hide perimenopause symptoms, so speak to your GP or a sexual health clinic about the right time to stop.

If you’re hoping to get pregnant. If you’re in your 40s and hoping to conceive, it’s worth getting advice sooner rather than later, because fertility falls more quickly at this stage. A Fertility Advisor Call can help you understand your options.

How can I prepare for perimenopause?

You can’t stop perimenopause from happening, but preparing for it can make the transition easier and help you spot changes early. These steps are worth taking in your late 30s and 40s, before symptoms start.

Find out about your family history. The age your mother or sisters went through menopause can give you a rough idea of when it might happen for you. It’s not a guarantee, but it can help you plan. Find out more about whether you can predict when menopause will happen.

Get to know your normal. Tracking your cycle and how you feel, in an app or a diary, makes it much easier to notice when something changes. If you do see a doctor, a record of your periods, sleep, mood and other symptoms over a few months gives them a much clearer picture.

Look after your bones and heart now. Your risk of osteoporosis and heart disease rises as oestrogen falls, so the habits you build now really matter. Regular exercise, including strength and weight-bearing activity, helps protect your bones and muscles. The NHS also recommends a daily 10 microgram vitamin D supplement, particularly in autumn and winter.

Build healthy habits. Habits that are easier to start before symptoms begin make a real difference once they do:

• eating a balanced diet
• keeping to a healthy weight
• cutting down on alcohol
• stopping smoking
• having a regular sleep routine
• finding ways to manage stress

Keep up with your health checks. If you live in England and you’re 40 or over, you’re entitled to a free NHS Health Check every five years. It checks your blood pressure, cholesterol and risk of conditions such as diabetes and heart disease. Keep up with cervical screening too, and breast screening once you’re invited.

Think about your fertility plans. If you’d still like to have children, don’t wait for perimenopause to start before thinking about your options, because fertility falls more quickly in your late 30s and 40s. Hertility’s Advanced Hormone and Fertility Test can show your ovarian reserve. A Fertility Advisor Call can help you weigh up options such as trying sooner or egg freezing.

Have a plan for contraception. You’ll still need contraception during perimenopause if you don’t want to get pregnant, so think about which method suits you as you get older. Some methods can also help with symptoms. For example, a hormonal coil can ease heavy periods, and it can also be used as part of HRT later on.

Learn about your treatment options. Knowing what HRT and other treatments involve before you need them makes it easier to ask for help when symptoms start. A Menopause Consultation gives you time to ask questions, even before you have symptoms.

Talk about it. Talking to your partner, friends, family or employer about perimenopause can make it easier to ask for support when you need it. Many workplaces now offer menopause support or adjustments.

What treatments are there for perimenopause symptoms?

You don’t need to wait until your periods stop to get help with perimenopause symptoms. The right treatment depends on which symptoms affect you most, your health and medical history, and whether you need contraception. A GP or menopause specialist can help you weigh up your options.

Hormone replacement therapy (HRT)

HRT replaces the hormones your body is making less of, and it’s the most effective treatment for many perimenopause symptoms.

HRT usually contains oestrogen, which comes as tablets, patches, gels or a spray. If you have a womb, you’ll also need a progestogen. Taking oestrogen on its own can make your womb lining thicken, which raises the risk of womb cancer, and the progestogen protects against this. You can take it as tablets or through a hormonal coil, such as the Mirena.

Changes to your periods and heavy bleeding

Before you start any treatment for bleeding problems, it’s important to have a proper check-up. Perimenopause is a common cause of irregular or heavy bleeding, but it isn’t the only one. Your doctor may suggest tests to rule out other causes, such as fibroids, polyps or changes to your womb lining. These tests could include a blood test for anaemia, a pelvic ultrasound scan or a biopsy of your womb lining.

If the bleeding is caused by perimenopause, treatment options include:

• A hormonal coil, such as the Mirena. It can make periods much lighter, it works as contraception, and it can later provide the progestogen part of HRT.
• The combined contraceptive pill. It can make bleeding lighter and more regular. It’s only suitable for some people in their 40s, depending on things such as your blood pressure and whether you smoke.
• Progestogen tablets. These can help control irregular or heavy bleeding.
• Non-hormonal medicines. Tranexamic acid or anti-inflammatory painkillers, such as mefenamic acid, can reduce heavy bleeding when you take them during your period.

Your doctor can help you decide which suits you best, depending on whether you also need contraception or help with other symptoms. A Private Gynaecologist Consultation can also help if your bleeding is heavy or hard to manage.

Hot flushes and night sweats

HRT. HRT is the most effective treatment for hot flushes and night sweats.

Non-hormonal medicines. If you can’t or would rather not take HRT, other medicines may help. These include some antidepressants and medicines such as clonidine or gabapentin. Some of these are mainly used for other conditions, but they can reduce hot flushes, and some may also help with sleep or mood. Your doctor can explain the side effects of each.

Talking therapy. Cognitive behavioural therapy (CBT) can help you cope with hot flushes and night sweats, as well as low mood and anxiety.

Everyday changes. Simple changes can make hot flushes easier to manage:

• keep your bedroom cool and use a fan
• wear light layers you can take off easily
• notice and cut down on your triggers, such as caffeine, alcohol and spicy food
• stop smoking
• exercise regularly

Vaginal dryness and urinary symptoms

Vaginal and urinary symptoms are among the easiest perimenopause symptoms to treat, and treatment has very few side effects. So don’t put up with them. Talk to your GP or a menopause specialist.

Vaginal oestrogen. Low-dose oestrogen that you put directly into your vagina, as a cream, gel, pessary (small tablet) or ring, can treat dryness, discomfort and urinary symptoms such as needing to wee more often or recurrent urinary infections. Very little is absorbed into the rest of your body, so it’s suitable for most people. It can be used for as long as you need it, and alongside HRT if you’re taking it.

Vaginal moisturisers. You use these regularly, a few times a week, to help keep the tissues in your vagina moist and comfortable day to day. You can buy them from pharmacies without a prescription, or get them prescribed.

Lubricants. Use a lubricant during sex to reduce dryness and discomfort. Water-based lubricants are safe to use with condoms. Oil-based ones can damage latex condoms, so avoid them if you’re using condoms for contraception.

Moisturisers and lubricants can be used on their own or alongside vaginal oestrogen. Some products can irritate sensitive skin, so it’s worth choosing fragrance-free options.

Mood, anxiety and sleep

HRT. HRT can help with low mood, anxiety and sleep problems linked to perimenopause, particularly if night sweats are waking you up.

CBT. CBT is also effective for low mood and anxiety during perimenopause.

If your mood is affecting your daily life, speak to your GP, or talk to one of our counsellors.

Low libido

If perimenopause has lowered your libido. HRT and treatment for vaginal dryness often help. If they don’t, your doctor may consider testosterone alongside HRT.

For more ways to manage your symptoms day to day, read our 8 ways to help with perimenopause symptoms, and find out more about menopause stages, symptoms and treatments.

Why perimenopause matters for your long-term health

As your oestrogen levels fall, your risk of some conditions starts to rise. Lower oestrogen can weaken your bones, increasing the risk of osteoporosis, and it can also affect your heart health. Staying active, including strength and weight-bearing exercise, eating a balanced diet with enough calcium and vitamin D, and not smoking all help protect your long-term health. For some people, HRT can help too.

When should you see a doctor about perimenopause?

Speak to your GP or a menopause specialist if:

• your symptoms are affecting your daily life, work, relationships or wellbeing
• you’re under 45 and think you might be in perimenopause
• you’re under 40 and your periods have become irregular or stopped
• you’d like to talk about HRT or other treatments
• you’re not sure whether your symptoms are caused by perimenopause or something else

See your GP promptly if you have:

• very heavy periods, or periods that last much longer than usual
• bleeding between periods or after sex
• any bleeding after you’ve gone 12 months without a period
  

How Hertility can help with perimenopause

Whether you’re trying to work out what’s going on or you know it’s perimenopause and want help with your symptoms, Hertility can support you:

• A Menopause Counsultation gives you time with a menopause specialist to talk through your symptoms and treatment options, including HRT prescriptions where appropriate.
• Whatever your age, Hertility’s Advanced Hormone and Fertility Test can help you understand what’s behind your symptoms, including checking your thyroid and other markers that can cause similar symptoms. Our clinicians interpret your results alongside your symptoms, cycle and health history.
• Counselling can support you if perimenopause is affecting your mental health.

Not sure where to start? Take the Online Health Assessment and we’ll build a personalised plan around your symptoms and goals.

Frequently asked questions

References:

1. British Menopause Society (2026). BMS Tool for Clinicians: What is the menopause? https://thebms.org.uk/wp-content/uploads/2026/01/17-NEW-BMS-TfC-What-is-the-menopause-JAN2026-A.pdf
2. NHS. Menopause. https://www.nhs.uk/conditions/menopause/
3. NHS. Menopause: symptoms. https://www.nhs.uk/conditions/menopause/symptoms/
4. NHS. Early menopause. https://www.nhs.uk/conditions/early-menopause/
5. National Institute for Health and Care Excellence (NICE). Menopause: identification and management (NG23). https://www.nice.org.uk/guidance/ng23
6. NHS Scotland / Right Decisions (2026). Menopause and HRT Guidelines.https://www.rightdecisions.scot.nhs.uk/tam-treatments-and-medicines-nhs-highland/adult-therapeutic-guidelines/sexual-health/menopause-guidelines/menopause-and-hrt-guidelines/ 
7. Avis NE, Crawford SL, Greendale G, et al. Duration of menopausal vasomotor symptoms over the menopause transition. JAMA Internal Medicine. 2015;175(4):531–539. https://doi.org/10.1001/jamainternmed.2014.8063
8. Faculty of Sexual and Reproductive Healthcare (FSRH). Contraception for women aged over 40 years. https://www.fsrh.org/Public/Documents/fsrh-guideline-contraception-for-women-aged-over-40-years-2017.aspx
9. NHS. Hormone replacement therapy (HRT). https://www.nhs.uk/medicines/hormone-replacement-therapy-hrt/
10. NHS. Osteoporosis. https://www.nhs.uk/conditions/osteoporosis/
11. NICE. Heavy menstrual bleeding: assessment and management (NG88). https://www.nice.org.uk/guidance/ng88