A hot flush is a phenomenon as disruptive as it is commonplace. One moment, life proceeds as usual. The next, a wave of heat rises, spreading from the chest to the face - leaving behind flushed skin and beads of sweat. For many, this sudden warmth is accompanied by an accelerated heartbeat and a faint sense of unease . Though brief - typically lasting anywhere from 30 seconds to five minutes - its intensity can be startling and made worse by unpredictable timing.
Author
- Michelle Spear
Professor of Anatomy, University of Bristol
A recent viral video has brought attention to just how intense a hot flush can be. The video depicts a woman named Tracey Monique experiencing a hot flush while at an outdoor event. In the video, her head is literally steaming.
The sight of wisps of vapour escaping her head highlighted the dramatic effects of this common perimenopausal symptom . Often misunderstood or trivialised, the image of a hot flush brings fresh attention to a phenomenon that affects an estimated 75% of people experiencing perimenopause .
The video has also sparked debate on social media - reflecting the complexity of hot flushes themselves. Some argue the steam escaping Monique's head was caused by her removing her hat while being in the cold. But many women have commented, saying the video perfectly encapsulates what a hot flush feels like.
Let's take a look at what's actually happening during a hot flush and why they can feel so severe.
Hormonal instigators
At the heart of a hot flush lies oestrogen - a hormone critical role in regulating body temperature in women. Oestrogen directly influences the hypothalamus , a small but essential structure in the brain often referred to as the body's thermostat . The hypothalamus monitors and adjusts body temperature to maintain balance.
Under normal circumstances, the hypothalamus keeps the body within a narrow temperature range - adjusting blood flow and sweat production as needed. But during perimenopause, oestrogen levels fluctuate unpredictably and eventually decline. These hormonal shifts disrupt the hypothalamus's ability to maintain its usual set temperature.
Declining oestrogen levels also make the hypothalamus overly sensitive to small changes in body temperature - misinterpreting these as signs of overheating . This triggers an exaggerated response aimed at cooling the body down: a hot flush. The result is a sudden dilation of blood vessels, particularly in the skin of the upper body, to allow heat to radiate outward. Simultaneously, sweat glands activate - intensifying the sensation of heat.
Luteinising hormone , which primarily regulates ovulation, also plays a secondary role in hot flushes. As oestrogen levels decline, the pituitary gland (which regulates key hormones that control growth, reproduction and metabolism) releases erratic surges of lutenising hormone. These spikes appear to further heighten the hypothalamus's sensitivity, amplifying its misinterpretation of normal body temperature as overheating.
The cooling response
During a hot flush the hypothalamus sends urgent signals to the autonomic nervous system, which governs involuntary functions such as heart rate, blood pressure and sweating. This prompts blood vessels near the skin to dilate - a process called vasodilation . This allows more blood to flow to the surface to release heat. This is why the face, neck and chest can feel intensely warm and look visibly flushed during a hot flush.
Almost simultaneously, the hypothalamus activates sweat glands in the upper body. Sweating is meant to cool the body through evaporation. In cold environments, this sweat may produce visible steam - as seen in Monique's viral video.
But once the hypothalamus realises the body isn't actually overheated, vasodilation subsides and blood vessels return to their normal state. But the rapid cooling effect from sweating can leave women feeling chilled . This creates a rollercoaster of sensations during and after the hot flush.
This sequence - heat, flush, sweat and chill - reflects the body's struggle to regain equilibrium in response to a misfiring thermostat.
The debate
While the sensation of heat is undeniable, whether hot flushes significantly raise skin temperature remains debated.
Thermographic studies , which use infrared imaging to measure heat patterns and surface temperature, have demonstrated measurable skin temperature rises - particularly in the face, neck and chest.
But other research has found only minor or negligible changes in skin temperature. This raises questions about whether the perception of heat correlates directly with physiological changes.
Critics suggest that the sensation of heat stems more from the brain's altered thermoregulation than from actual warming of the skin. Tools such as thermographic imaging may also miss subtle or transient temperature changes - or these changes may be masked by sweat evaporation.
It may also be the case that skin temperature changes , like other perimenopausal symptoms, vary widely between people. The variability in oestrogen levels contributes significantly - with those experiencing more erratic hormonal changes often reporting more intense or frequent flushes. Factors such as genetics, lifestyle and environmental triggers , all add to the diversity of experiences and how intense symptoms might be.
Hot flushes are a complex interplay of hormonal, neurological and vascular responses. While the scientific debate about skin temperature changes remains unresolved, the lived experience of heat and discomfort is undeniable. For many, these symptoms are disruptive and even debilitating, profoundly affecting daily life.
Monique's viral video, with the striking image of steam rising from her head, has resonated deeply with countless women - offering stark visual evidence of what they've felt but often struggled to articulate. Understanding the anatomy of a hot flush not only sheds light on its mechanisms but also underscores the importance of empathy and tailored approaches to managing this multifaceted symptom.
Michelle Spear does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
