What is happening
A hot flash is a heat-dumping reflex firing when it should not. Your brain keeps your core temperature inside a narrow comfortable band. As estrogen falls, that band gets narrower — so a small rise in core temperature, one that would have meant nothing at 40, now reads as overheating. Your body responds the way it responds to real overheating: blood vessels near the skin open, you flush, and you sweat. A few minutes later the heat loss overshoots and you feel cold.
That is why hot flashes feel like they come from nowhere. Nothing is wrong with your thermostat’s wiring. The set point it is defending has shifted.
Why menopause causes it
The current understanding centers on a group of nerve cells in the hypothalamus called KNDy neurons. Estrogen normally restrains them. When estrogen falls, these neurons grow larger and signal more, and the neuropeptide they release — neurokinin B — pushes on the temperature control center next door. This is not a side theory. It is the mechanism that fezolinetant and elinzanetant were designed around: both block the neurokinin receptor, and both reduce hot flash frequency and severity in randomized trials without using any hormone.
Roughly three out of four women get vasomotor symptoms during the menopause transition, and about a third describe them as moderate to severe. Symptoms usually begin in perimenopause, while periods are still happening, and often peak in the year or two after the final period.
How we approach it
We start by asking how many flashes you get, how bad they are, and what they cost you — sleep, work, driving, intimacy. That number becomes the thing we measure against, not a lab value. Blood hormone levels bounce around too much during the transition to guide treatment, so we usually do not check them unless there is a specific question, such as symptoms before age 40.
Then we go through your history: mammogram date, any personal history of breast cancer, blood clots, stroke, migraine with aura, or liver disease, and whether you still have a uterus. That conversation decides which options are on the table before we talk about preferences.
If systemic hormone therapy is appropriate, it is the most effective treatment available for these symptoms and it also protects bone. If it is not appropriate, or you would rather not use it, the non-hormonal prescriptions are not a consolation prize — they work, and we use them every day.
Whatever we start, we follow the same symptom score over time in the app, so a dose change is a decision based on your own numbers rather than a guess.