Perimenopause is not a switch that flips. It is a multi-year renegotiation of the hormonal signalling between the ovaries and the brain, and it typically starts in the mid-forties - several years before most women connect their symptoms to menopause at all. Understanding the sequence helps you recognise what is happening and decide when treatment is worth discussing.
Early perimenopause: progesterone falls first
The earliest change is usually not estrogen but progesterone. Ovulation becomes less reliable, and cycles without ovulation produce little progesterone. Because progesterone is the calming, sleep-supporting hormone, the first symptoms many women notice are shorter cycles, heavier bleeding, new premenstrual anxiety, and waking at 3am. Estrogen at this stage is often normal or even elevated, which is why blood tests taken early in perimenopause frequently come back "fine."
Mid perimenopause: estrogen becomes erratic
As follicle numbers drop, estrogen stops declining smoothly and starts swinging. Those swings - not low levels - drive the classic instability of this phase: hot flashes that appear without warning, night sweats, migraines, mood swings, and brain fog. Cycles lengthen and become unpredictable. This is the stage when symptom burden is usually highest, and also when hormone therapy tends to make the biggest difference.
Late perimenopause and the transition to menopause
Once you skip periods for 60 days or more, you are in late perimenopause. Estrogen settles at a persistently low level, and tissue-dependent symptoms come to the front: vaginal dryness, urinary urgency, joint pain, and accelerating bone turnover. Vasomotor symptoms often continue for years after the final period.
When to consider treatment
You do not need to wait for confirmed menopause to start hormone therapy. Current guidance from the Menopause Society supports treating symptomatic women during perimenopause, and starting within ten years of the final period is associated with the most favourable risk-benefit profile. If symptoms are disrupting sleep, work, or relationships, that is a sufficient reason to have the conversation. Our perimenopause HRT guide compares the telehealth providers that treat women in active transition rather than only after menopause is confirmed.
Symptoms that are easy to miss
Many women expect hot flashes and irregular periods, and they are surprised by everything else. Heart palpitations, new or worsening migraines, itchy skin, tinnitus, 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, without any change in your circumstances, is one of the most common reasons women are wrongly told that nothing is wrong. None of these symptoms is dangerous on its own, 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, and sometimes from hour to hour. A normal result on a Tuesday says very little about how you will feel on Friday. For women over 45, current guidance is that perimenopause is diagnosed from symptoms and age, not from a hormone test. Blood tests still have a role: a thyroid panel, ferritin, and vitamin D can uncover 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.
Keeping a simple symptom diary
One of the most useful things you can do before a consultation is to track what happens for two to three months. Note the dates of any bleeding, the nights you wake, hot flashes or sweats, mood dips, and anything that seems to trigger them. 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 symptom-tracking 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 daylight in the morning all help sleep. Cognitive behavioural therapy has good evidence for hot flashes, low mood, and insomnia in the transition. If you are not able or do not want to use hormones, non-hormonal medicines such as low-dose antidepressants, gabapentin, or fezolinetant are options worth raising with your clinician.
Frequently asked questions
How long does perimenopause last?
The average is about four years, but it can be as short as a few months or as long as ten years. Menopause itself is confirmed after twelve months without a period.
Can I still get pregnant?
Yes. Ovulation becomes unpredictable but has not stopped, so contraception remains necessary until menopause is confirmed.
Is it normal to feel anxious for no reason?
It is common, and it is hormonally driven for many women. If anxiety is constant or interferes with daily life, speak to a clinician, because it is treatable.