Perimenopause

The transition begins years before periods stop, and it is easy to miss because the symptoms are non specific, the cycle is still present, and hormone levels swing rather than simply fall.

What is happening

Ovarian follicle numbers decline steadily throughout life. As they fall, ovulation becomes less regular and the hormonal signalling between the brain and the ovaries becomes erratic. Oestrogen levels do not simply drop; they swing, sometimes reaching levels higher than in a normal cycle and sometimes falling well below. Progesterone falls more consistently because it depends on ovulation having happened.

That pattern explains why perimenopause feels chaotic rather than gradual. It also explains why a single blood test is a poor way to identify it: a level taken on one day may look entirely ordinary and a level taken two weeks later may not.

When it starts

Most commonly in the mid forties, though the range is wide and starting in the late thirties is not rare. The transition typically lasts around four years, but some women pass through it in under a year and others take a decade. Smoking is associated with an earlier menopause. A family pattern is often, though not always, informative.

How periods change

The usual sequence is that cycles first become slightly shorter, so periods arrive more often. Bleeding may become heavier or lighter. Later, cycles lengthen and become irregular, with gaps of several weeks or months. Missed periods followed by a return of bleeding are normal in this phase.

Some patterns are not part of normal perimenopause and should be assessed: bleeding between periods, bleeding after sex, periods that are so heavy that they soak through protection hourly or contain large clots, and any bleeding after twelve months without one.

Symptoms

The commonly recognised ones are hot flushes and night sweats, described together as vasomotor symptoms. They vary from a mild flush to drenching sweats that interrupt sleep repeatedly.

Beyond those, the list is long and the symptoms are individually non specific, which is precisely why perimenopause is missed.

• Sleep that is broken, or waking at three in the morning and staying awake.
• Low mood, irritability, anxiety that feels unfamiliar, or reduced tolerance for stress.
• Difficulty concentrating and word finding, often described as brain fog.
• Joint and muscle aches, and stiffness in the mornings.
• Palpitations, which should be mentioned to a clinician rather than assumed.
• Headaches or a change in migraine pattern, often linked to the cycle.
• Reduced libido, which has hormonal, physical and situational components at once. See low libido.
• Vaginal dryness and urinary changes, which usually begin later but can appear during perimenopause and do not resolve on their own. See genitourinary syndrome of menopause.
• Skin and hair changes, including dryness and thinning.

Individually, each of these has other explanations. Thyroid disease, anaemia, depression, sleep disorders and iron deficiency all overlap. That is a reason to describe the whole pattern at an appointment rather than a single symptom.

Diagnosis

For a woman over forty five with typical symptoms and a changing cycle, current guidance is that no blood test is needed: the diagnosis is clinical. Tests of follicle stimulating hormone are unreliable during perimenopause because levels fluctuate, and they can be misleading in women using hormonal contraception.

Testing is appropriate in specific situations: when symptoms appear before forty five, when menopause is suspected before forty, and sometimes when the picture is unclear or the uterus has been removed. Other conditions may be excluded with blood tests, and that is a different purpose from diagnosing menopause itself.

Treatment

Hormone replacement therapy is effective for vasomotor symptoms and is available in several forms. Whether it is suitable depends on medical history, age, and personal preference after a discussion of the balance of benefits and risks, which differs by age and by the type used. That conversation belongs with a prescriber.

Non hormonal prescription options exist for hot flushes and are worth asking about, particularly where hormones are unsuitable. Cognitive behavioural therapy has reasonable evidence for hot flushes, sleep and mood in this context.

Practical measures help more than they are given credit for: keeping the bedroom cool, layered clothing, identifying personal triggers such as alcohol, caffeine or spicy food, regular exercise including resistance work for bone and muscle, and a consistent approach to sleep. None of these is a cure, and presenting them as one is the reason they are often dismissed.

Contraception

Fertility falls but does not disappear. Pregnancy during perimenopause is uncommon and entirely possible. Standard advice is to continue contraception until twelve months after the last period for women aged fifty and over, and until twenty four months after the last period for women under fifty. Some hormonal methods also help with heavy bleeding during this phase. See the contraception overview.

Keeping a record

Symptoms that fluctuate are hard to report accurately. A few weeks of notes on cycle dates, flushes, sleep and mood turns a vague account into something a clinician can act on, and often reveals a pattern the person had not seen. The menopause symptom record provides a structure, and the question list for a menopause consultation is worth taking along.

Last reviewed: September 2026