It is not just estrogen dropping. How estrogen, progesterone and testosterone each change in perimenopause, on different timelines, and why that explains your symptoms.
The Three Hormones of Perimenopause: Estrogen, Progesterone and Testosterone
The short answer: perimenopause is not simply “estrogen dropping”. Three hormones change through the transition, each on its own timeline and with its own effects, and understanding all three makes sense of a symptom picture that otherwise feels bafflingly scattered. Estrogen (oestrogen) is the headline hormone, but its defining feature in perimenopause is erratic fluctuation, not a smooth decline. Progesterone often falls first, and because it feeds the brain’s main calming system, its loss drives early anxiety, poor sleep and heavier periods before anyone mentions menopause. Testosterone, which women very much have, declines gradually and quietly affects libido, energy and motivation. Seeing the interplay of all three, rather than fixating on one, is what turns confusion into a coherent, explicable story.
Most of what women are told about perimenopause begins and ends with “your estrogen is dropping”. That is true as far as it goes, but it is only part of the picture, and the incompleteness matters, because it leaves a whole set of symptoms unexplained and often misattributed to stress or personality. Three hormones shift significantly during the transition, each contributing differently to how you feel, and they do not move in step. Once you understand what each one does and when it changes, the seemingly random collection of symptoms, the anxiety that came years before the hot flashes, the flattened libido, the disrupted sleep, resolves into a pattern that actually makes sense.
Estrogen: the headline hormone, but not a simple decline
Estrogen is the primary female sex hormone and it is central to the menopause story for good reason: it acts almost everywhere. It influences bone density, cardiovascular health, skin collagen, the vaginal and urinary tissues, brain function and mood, sleep, and where the body stores fat. The symptoms most associated with menopause, hot flashes and night sweats, brain fog, vaginal dryness, much of the mood disturbance, are in large part estrogen-related, which is why it dominates the conversation and why hormone therapy centred on estrogen relieves so many symptoms at once.
The crucial and widely misunderstood point is that in perimenopause estrogen does not glide gently downward. It fluctuates, often wildly, surging higher than normal in some cycles and dropping sharply in others, because the ovaries are winding down erratically rather than switching off cleanly. This volatility is precisely what makes perimenopause so destabilising, and it is why “low estrogen” is an inaccurate description of the phase: for much of perimenopause the problem is unpredictable estrogen rather than uniformly low estrogen. The genuinely low, stable level only arrives in postmenopause, which is a different experience, as our guide to the three stages explains.
Progesterone: the calming hormone that often goes first
Progesterone is frequently the first of the three to decline, often several years before estrogen falls meaningfully, and its effects are felt as much in the nervous system as in the body. In the brain it is converted into allopregnanolone, a compound that boosts the activity of GABA, the brain’s main calming, anti-anxiety neurotransmitter, the same system that anti-anxiety medications act on. When progesterone is plentiful this provides a kind of neurological shock absorber; as it declines and fluctuates, that buffer thins and the brain becomes more reactive to stress.
The consequences show up as increased anxiety, disrupted and lighter sleep, heightened emotional reactivity and irritability, and, because progesterone also helps regulate the uterine lining, heavier or more erratic periods. Because these often arrive early, before hot flashes and before anyone is talking about menopause, they are among the most commonly missed and misattributed symptoms of all, frequently blamed on stress or a mood disorder. Recognising progesterone’s role explains a great deal that estrogen alone cannot, and it connects directly to what we cover in perimenopause anxiety and mood swings. The type of progesterone in hormone therapy also matters, since body-identical (micronised) progesterone tends to be better tolerated neurologically than older synthetic progestogens.
Testosterone: the hormone women are not told they have
Women produce testosterone throughout life, from the ovaries and adrenal glands, and it is a human hormone rather than a male one, present in both sexes in different amounts. In women it contributes to libido, energy, motivation and drive, cognitive focus, muscle maintenance and a general sense of vitality and confidence. Its decline is not sudden at menopause; it begins gradually from around the mid-twenties and continues through midlife, so by perimenopause many women are working with substantially less than they had in their twenties.
The symptoms linked to low testosterone in women, reduced libido, fatigue, flattened motivation and drive, diminished muscle tone, and for some a foggy lack of focus, overlap heavily with other perimenopausal symptoms, which is exactly why low testosterone is so easily overlooked and rarely tested for. Testosterone therapy is increasingly discussed by menopause specialists and has the strongest evidence for improving libido specifically; it is not routinely offered everywhere and is usually considered after estrogen has been addressed, but it is worth asking about if low libido, energy or motivation is a significant concern. Our guide to low libido in perimenopause goes deeper on this.
How the three interact
The reason perimenopause feels so chaotic is that these three hormones are not changing neatly or in sequence but shifting on overlapping, individual timelines, and they influence one another and shared systems. Fluctuating estrogen destabilises the brain chemicals serotonin and dopamine; declining progesterone removes calming GABA support; falling testosterone drains energy and drive; and the resulting poor sleep amplifies every other symptom the next day. A single bad stretch might reflect an estrogen surge, a progesterone trough and accumulated sleep debt all at once, which is why symptoms cluster, contradict each other and refuse to map onto a tidy timeline.
This is also why a single blood test is a poor tool for diagnosing perimenopause: levels swing day to day and even within a day, so one snapshot rarely captures the picture, and diagnosis usually rests on symptoms, age and the changing pattern of periods instead, as our guide to testing in perimenopause explains. It also explains why standard hormone therapy helps some symptoms more than others. Because conventional HRT replaces estrogen and progesterone but not testosterone, some women on HRT still notice low libido or energy, which is where a specialist discussion about adding testosterone can come in. Understanding the three-hormone picture is what lets you and your clinician target treatment to what is actually driving your particular symptoms.
Frequently Asked Questions
Do women really have testosterone?
Yes. Women produce testosterone in the ovaries and adrenal glands throughout life, and it plays important roles in libido, energy, motivation, cognitive focus and muscle maintenance. It is not a male hormone but a human one, present in both sexes in different amounts. Women’s levels decline gradually from around the mid-twenties, so by perimenopause many are working with considerably less than in earlier adulthood, which can affect drive and libido.
Why does progesterone matter if estrogen gets most of the attention?
Because progesterone’s effects on the nervous system, on anxiety, sleep and emotional regulation, are significant and often arrive first, sometimes years before estrogen falls meaningfully. Progesterone supports the brain’s calming GABA system, so as it declines, anxiety, poor sleep and irritability can appear early and be misattributed to stress. Understanding its role explains a set of symptoms that estrogen alone does not account for.
Can I get all three hormones tested?
A panel including estrogen, progesterone and testosterone can be requested, but interpreting the results requires context and expertise, because levels fluctuate enormously day to day in perimenopause, so a single snapshot can be misleading. In perimenopause, diagnosis usually rests on symptoms, age and period pattern rather than blood tests. A doctor or menopause specialist can advise what is worth testing, when, and how to interpret it.
Why does standard HRT address some symptoms but not others?
Standard hormone therapy replaces estrogen and progesterone (the latter to protect the womb lining), which is why it relieves estrogen- and progesterone-related symptoms well. It does not include testosterone, so some women on HRT still experience low libido, energy or motivation, and this is where a specialist may discuss adding testosterone. Matching treatment to which hormones are driving your symptoms is the key to getting the most from it.
Which hormone causes hot flashes?
Hot flashes are primarily driven by fluctuating and falling estrogen, which makes the brain’s temperature-regulating thermostat oversensitive. Because it is the fluctuation rather than simply the low level that triggers them, hot flashes commonly begin in perimenopause while estrogen is still swinging, sometimes years before periods stop. Progesterone and testosterone are not the main drivers of hot flashes, though poor sleep and other symptoms can make them feel worse.
Which hormone changes first in perimenopause?
For many women, progesterone declines first, often before estrogen falls significantly, which is why early symptoms are frequently anxiety, disrupted sleep, irritability and heavier periods rather than hot flashes. Estrogen then begins its erratic fluctuation, and testosterone declines gradually across the whole period. The exact order and pace vary between individuals, which is part of why perimenopause is experienced so differently from one woman to another.
Further Reading
- The Menopause Society. Hormonal changes of the menopause transition. https://menopause.org/patient-education/menopause-topics
- American College of Obstetricians and Gynecologists (ACOG). The menopause years. https://www.acog.org/womens-health
- International Menopause Society. Testosterone in women. https://www.imsociety.org/
- Study of Women’s Health Across the Nation (SWAN). Hormone changes across the transition. https://www.swanstudy.org/
- NHS. Menopause: overview. https://www.nhs.uk/conditions/menopause/
This article is for general information and does not constitute medical advice. Hormonal changes and their treatment should be assessed individually. For personalised guidance, please consult a qualified healthcare professional or menopause specialist.
