Perimenopause is not a switch that flips. It is a multi-year renegotiation of the hormonal conversation between your ovaries and your brain, and it usually begins in the mid-forties, years before most women link their symptoms to menopause. Knowing the sequence helps you recognise what is going on and decide when treatment is worth raising.
Early perimenopause: progesterone drops first
The first change is typically progesterone, not estrogen. Ovulation gets less reliable, and cycles without ovulation make little progesterone. Since progesterone is the calming, sleep-supporting hormone, the earliest signs many women notice are shorter cycles, heavier bleeding, new premenstrual anxiety and waking at 3am. Estrogen at this point is often normal or even high, which is why blood tests taken early in perimenopause so often come back "fine."
Mid perimenopause: estrogen turns erratic
As the number of follicles falls, estrogen stops sliding down smoothly and starts to swing. Those swings, rather than low levels, drive the instability of this phase: hot flashes with no warning, night sweats, migraines, mood swings and brain fog. Cycles lengthen and become unpredictable. This is usually when symptoms are at their heaviest, and also when hormone therapy tends to help most.
Late perimenopause and the move into menopause
Once you skip periods for 60 days or more you are in late perimenopause. Estrogen settles at a persistently low level, and symptoms tied to tissue take centre stage: vaginal dryness, urinary urgency, joint pain and faster bone turnover. Vasomotor symptoms often carry on for years after the final period.
When to think about treatment
You do not have to wait for confirmed menopause to begin hormone therapy. Current Menopause Society guidance supports treating symptomatic women during perimenopause, and starting within ten years of the final period gives the most favourable balance of benefit and risk. If symptoms are disrupting sleep, work or relationships, that alone is reason enough to have the conversation. Our perimenopause HRT guide compares the telehealth providers that treat women in active transition and not only after menopause is confirmed.
Symptoms that are easy to miss
Many women expect hot flashes and irregular periods and are caught off guard by everything else. Heart palpitations, new or worse migraines, itchy skin, ringing in the ears, burning mouth, tingling in the hands and feet, and sudden intolerance to alcohol or caffeine are all reported in the transition. Anxiety that appears for the first time in your mid-forties, with no change in circumstances, is one of the commonest reasons women are wrongly told nothing is wrong. None of these is dangerous alone, but together they form a recognisable pattern, and naming it can be a relief.
Why blood tests often do not help
Hormone levels swing from day to day in perimenopause, sometimes hour to hour. A normal result on Tuesday says little about how you will feel on Friday. For women over 45, current guidance is that perimenopause is diagnosed from symptoms and age, not a hormone test. Blood tests still have a role: a thyroid panel, ferritin and vitamin D can reveal other problems that mimic the transition, and a pregnancy test is worth taking if your periods stop suddenly. Our guide to hormone testing explains what each marker can and cannot tell you.
Keep a simple symptom diary
One of the most useful things you can do before a consultation is track what happens for two to three months. Note any bleeding dates, nights you wake, hot flashes or sweats, mood dips and possible triggers. A diary turns a vague sense of feeling unwell into evidence a clinician can act on, and it makes it much easier to judge whether a treatment is working. A paper calendar is enough, and many free apps do the same job.
What helps besides hormone therapy
Regular strength training protects bone and muscle, which both decline faster as estrogen falls. Eating enough protein, keeping alcohol modest and getting morning daylight all help sleep. Cognitive behavioural therapy has good evidence for hot flashes, low mood and insomnia in the transition. If you cannot or prefer not to use hormones, non-hormonal medicines such as low-dose antidepressants, gabapentin or fezolinetant are worth raising with your clinician.
Frequently asked questions
How long does perimenopause last?
On average about four years, but anywhere from a few months to ten. Menopause itself is confirmed after twelve months without a period.
Can I still get pregnant?
Yes. Ovulation becomes unpredictable but has not stopped, so you need contraception until menopause is confirmed.
Is it normal to feel anxious for no reason?
It is common, and for many women it is hormone-driven. If anxiety is constant or gets in the way of daily life, talk to a clinician, because it is treatable.