First Signs of Perimenopause Starting: What to Expect

Q: What are the very first signs perimenopause is starting?

Changes to your menstrual cycle are often among the earliest signs. Your periods may arrive more or less often than usual, become heavier or lighter, or last a different length of time. You might also notice things like disrupted sleep, hot flushes, or mood changes before your cycle becomes irregular. If you are unsure, tracking your symptoms and speaking to your GP can help make sense of what is happening.

Q: What age does perimenopause typically start?

Perimenopause usually begins around the age of 45, and the average age of reaching menopause in the UK is around 51. It can start earlier than 45 for some. Symptoms that begin before the age of 40 can point to Premature Ovarian Insufficiency (POI), which is a separate condition and needs a GP assessment.

Q: Can perimenopause affect mood and memory?

Yes. Low mood, anxiety, irritability, trouble concentrating, and memory lapses are common during perimenopause and link back to fluctuating oestrogen. If these symptoms stick around or feel severe, it is worth speaking to your GP, as they may benefit from their own assessment and support alongside any perimenopause care.

Q: How long does perimenopause last?

The length of perimenopause varies a lot. It can run anywhere from a few months to around ten years, with an average of roughly four years before your periods stop completely. Because hormone levels swing unpredictably through this time, your symptoms can vary in intensity from week to week.

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Perimenopause is the stretch of time leading up to your final natural period, and it can start earlier than most people expect. The first signs are often easy to miss or put down to something else: a period that's slightly off, sleep that doesn't feel restorative, mood changes that seem to come from nowhere. Understanding what's happening, and why, can make this stage easier to navigate.¹

When does perimenopause typically begin?

Perimenopause usually starts from the age of 45, though it can begin earlier. In the UK, the average age to reach menopause, which is 12 months in a row without a period, is 51. The years leading up to that point can run from a few months to as long as a decade, and they average around four years.⁵

If your symptoms start before the age of 40, this is not typical perimenopause. Onset before 40 can point to Premature Ovarian Insufficiency (POI), a separate condition where the ovaries stop working earlier than usual. If this sounds like you, it is worth speaking to your GP, as POI needs its own assessment and care.²

Why oestrogen fluctuation causes so many symptoms

Some weeks can feel manageable while others are much harder, and that inconsistency is part of how perimenopause works. Most of your symptoms come down to your hormones shifting, especially oestrogen, as your ovaries gradually slow down. These shifts are often erratic and hard to predict rather than a smooth, steady decline. That is why how you feel can swing so much from week to week.⁶

How your cycle changes as the first sign perimenopause is starting

One of the earliest and most common signs that perimenopause has begun is a change in your usual period pattern. Your cycles might arrive more or less often than they used to. Your flow can become heavier or lighter, and your period may last a different length of time. The whole cycle can run shorter or longer than your normal.⁷

It is also worth knowing that other symptoms can turn up before your cycle becomes irregular. Changes to your sleep, mood, or body temperature may come before you notice any shift in your periods.⁸

Physical symptoms to be aware of

Beyond cycle changes, a wide range of physical symptoms can show up during perimenopause. These include:

Hot flushes
Night sweats
Sleep difficulties
Headaches or migraines
Joint aches
Heart palpitations
Vaginal dryness⁹

Psychological and cognitive symptoms

Changes to your mood and thinking are also very common during perimenopause, and they are often the symptoms that cause the most confusion. You might notice low mood, anxiety, or irritability alongside trouble with memory and concentration, sometimes called brain fog. You might also notice a dip in self-confidence.¹⁰

Hormonal changes feed into these experiences. Low mood and anxiety that stick around or feel severe still deserve their own assessment. If you are struggling with your mental health, speaking to your GP is a useful first step. NHS Talking Therapies can also support you with anxiety and low mood, and your GP can refer you, or you can refer yourself in England.

The wide range of individual experience

Symptoms and how strong they feel differ a lot from one person to the next. Perimenopause may have a real impact on your daily life, or your symptoms may be mild and barely noticeable.¹¹

How perimenopause is assessed

If you are over 45, your GP can assess perimenopause based on your symptoms alone. Routine blood tests to check your hormone levels are not usually needed at this age, because hormone levels swing too much during perimenopause to give a reliable result. If you are under 45 and noticing symptoms, your GP may look at blood tests alongside your symptom history.³

What to track and why it helps

Keeping a record of your symptoms over time is a practical, useful step. A symptom diary helps you spot patterns, see how things are changing, and gives your GP a clearer picture when you ask for support. You might note the date and length of your periods, any physical symptoms and when they crop up, and changes to your mood, sleep, or concentration.⁴

If your symptoms are affecting your daily life, or you are unsure whether what you are feeling is linked to perimenopause, booking an appointment with your GP is the most useful next step. You do not need to wait until things become severe.

Frequently Asked Questions

What are the very first signs perimenopause is starting?

What age does perimenopause typically start?

Do you need a blood test to confirm perimenopause?

Can perimenopause affect mood and memory?

How long does perimenopause last?

Sources

[1] Perimenopause and menopause: your questions answered

Perimenopause is the stretch of time leading up to your final period
[2] Early or premature menopause

If your symptoms start before the age of 40, this is not typical perimenopause,
[3] Perimenopause and menopause: your questions answered

For people over 45, a GP can make a clinical assessment based on symptoms alone. Routine blood tests to check hormone levels are not usually necessary in this age group.
[4] Understanding Menopause

Keeping a record of symptoms over time helps you notice patterns, track how things are changing, and gives your GP a clearer picture when you seek support.
[5] lscft.nhs.uk

The perimenopause transition can last from a few months to around ten years, with an average of approximately four years before periods stop completely.
[6] lscft.nhs.uk

The primary driver of perimenopausal symptoms is the fluctuation and eventual decline of hormones, particularly oestrogen, as the ovaries gradually slow down their function. These hormonal shifts are often erratic and unpredictable.
[7] Symptoms of menopause and perimenopause

One of the earliest and most common signs that perimenopause has begun is a change in your normal period pattern, including changes in frequency, flow, and duration. Cycles may become shorter or longer compared to your usual pattern.
[8] Symptoms of menopause and perimenopause

Other symptoms can appear before your cycle becomes irregular. Changes to sleep, mood, or body temperature may predate any noticeable shift in your periods.
[9] Symptoms of menopause and perimenopause

Common physical symptoms of perimenopause include hot flushes, night sweats, sleep difficulties, headaches or migraines, joint aches, heart palpitations, and vaginal dryness.
[10] Symptoms of menopause and perimenopause

Psychological and cognitive changes including low mood, anxiety, irritability, difficulty with memory and concentration (brain fog), and a reduction in self-confidence are common during perimenopause.
[11] Symptoms of menopause and perimenopause

Symptoms and their severity differ considerably from person to person. For some perimenopause has a significant impact on daily life; for others symptoms are mild or barely noticeable.