Do You Get Hot Flashes With COVID?

Hot flashes and episodes of sudden, drenching sweat are among the more disorienting symptoms people report during and after COVID-19 infection. They show up in both the acute illness and, more persistently, in long COVID. In one cross-sectional analysis of post-COVID clinic patients in England, roughly 62% reported hot flushes and 64% reported sweating at night, and those numbers held even among patients aged 18 to 39, well before the age when menopause-related hot flashes would be expected. The mechanisms behind these episodes are more complex than a simple fever, involving autonomic nerve dysfunction, persistent inflammation, mast cell activation, and hormonal disruption.

How Common Are Hot Flashes and Sweats After COVID

The short version is that they are surprisingly common, particularly among people dealing with lingering symptoms. A study across three post-COVID syndrome clinics in England found hot flushes in about 62% of patients and night sweats in about 64%, making vasomotor symptoms (the medical umbrella term for hot flashes and sweats) widespread in that population. What stood out was the age distribution: even in the 18-to-39 age group, about 61% reported hot flushes and night sweats, rates nearly identical to the older cohorts.¹ That finding alone suggests something beyond normal hormonal fluctuations is at play.

A national online survey in the Czech Republic captured a broader picture of post-COVID sleep disruption and found that about 38% of respondents reported night sweats after their infection. That survey also found an association between night sweats and female sex, though men were not immune to the symptom.² Another estimate puts persistent night sweats in long COVID at up to 25% of patients, with most cases going untreated until they eventually resolve on their own.³ Taken together, the evidence makes clear that hot flashes and sweating episodes are not rare oddities but a core part of the post-COVID experience for many people.

Why the Autonomic Nervous System Is Central to This

Your autonomic nervous system manages the involuntary functions you never think about: heart rate, digestion, blood pressure, and body temperature regulation. It has two branches that are supposed to balance each other, one that revs you up and one that calms you down. COVID-19 appears to knock that balance off-kilter, and the consequences include abnormal temperature control.

A study of 202 long COVID patients found measurable imbalances in this system. Heart rate variability, a reliable marker of autonomic function, was significantly altered compared to healthy controls. More directly relevant to hot flashes, patients in the earlier phase of long COVID (within 120 days of infection) had higher body surface temperatures across all regions measured than those further out from their initial illness. The researchers attributed this to reduced parasympathetic (calming branch) activation and sustained inflammatory signaling damaging the blood vessel lining.⁴

When the calming branch of the autonomic nervous system is suppressed, the body’s thermostat essentially becomes unreliable. Blood vessels near the skin dilate and constrict at the wrong times, sweat glands activate when they shouldn’t, and the result is the classic hot flash sensation: a sudden wave of heat, flushing, and perspiration that can hit without warning. This is the same basic mechanism behind menopausal hot flashes, where falling estrogen destabilizes the brain’s thermoregulatory center. In post-COVID patients, the destabilization comes from a different direction, but the subjective experience is strikingly similar.

Research into small nerve fiber damage adds another layer. A histological study of long COVID patients with pain symptoms found that nerve fiber density in the skin was significantly reduced compared to healthy controls, even in patients whose standard nerve tests came back normal.⁵ These small fibers are exactly the ones that regulate sweating and blood vessel tone. When they are damaged or depleted, the body loses fine-grained control over temperature, making hot flashes and excessive sweating more likely.

What Happens Inside the Brain

The autonomic dysfunction story gets more interesting when you look at what COVID does to brain temperature itself. A neuroimaging study measured brain temperature before and after mild COVID-19 infection and found significant increases in specific regions, particularly areas involved in smell processing. The largest increase was in the left olfactory tubercle, where brain temperature rose by an average of 1.75°C. Patients who had lost their sense of smell showed an even more dramatic increase of over 3°C in that same region.⁶

Brain temperature is not the same thing as body temperature measured with a thermometer. It reflects local metabolic activity and inflammation within neural tissue. These findings suggest that even a mild infection can create pockets of neuroinflammation that persist after the virus clears. Whether this directly triggers hot flashes is not yet established, but the brain’s thermoregulatory center (the hypothalamus) sits in the neighborhood of these affected regions. Inflammation nearby could plausibly make it more reactive, lowering the threshold at which it triggers a heat-dissipation response, in other words a hot flash.

Mast Cells and the Allergy-Like Cascade

One of the more compelling explanations for post-COVID hot flashes involves mast cells, the immune cells responsible for allergic reactions. When mast cells activate, they dump histamine and other inflammatory chemicals into surrounding tissue, causing flushing, heat, itching, and sweating. Research has found that long COVID patients show signs of overactive mast cells, with abnormal granulation and excessive release of inflammatory mediators.⁷ The clinical picture in these patients closely resembles a condition called mast cell activation syndrome, where mast cells fire inappropriately and produce waves of symptoms including flushing, sweating, rapid heartbeat, and gastrointestinal distress.

A separate study comparing symptom severity before and after COVID-19 found that sweats, along with fatigue, muscle pain, and chest symptoms, were significantly worse in long COVID participants than they had been before infection.⁸ This is an important detail because it rules out the possibility that these patients simply had pre-existing sweating issues. Their symptoms got measurably worse after COVID.

The mast cell connection helps explain why some post-COVID patients find partial relief from antihistamines. If mast cells are driving periodic histamine surges, blocking histamine receptors can blunt the flushing and sweating. This is not a cure for long COVID by any stretch, but for people whose hot flashes are driven by this mechanism, it can take the edge off.

Night Sweats and the Glucose Hypothesis

Night sweats deserve their own discussion because they disrupt sleep in a way that daytime hot flashes do not, and because an intriguing hypothesis links them to how the body handles energy during sleep. Researchers proposed that because SARS-CoV-2 disrupts glucose metabolism and can impair mitochondrial function, the body burns through its stored glycogen faster during the night. When glycogen runs low, the body releases adrenaline to mobilize alternative fuel sources, and adrenaline triggers sweating. To test this, they had three non-diabetic long COVID patients with persistent night sweats eat carbohydrates before bed. After one week, all three reported their night sweats had completely disappeared.³

Three patients is a tiny sample, and this is a case series rather than a controlled trial. But the underlying logic is plausible: COVID-19 is known to affect insulin signaling and cellular energy production, and adrenaline surges during sleep are a recognized trigger for night sweats in other conditions like hypoglycemia. If your long COVID night sweats have been resistant to other approaches, having a small carbohydrate-containing snack before bed is low-risk enough to try. Think a piece of toast or a banana, not a heavy meal.

The Czech survey mentioned earlier found that women were statistically more likely to report night sweats than men after COVID, with about 39% of women affected compared to roughly 28% of men.² That sex difference could reflect hormonal factors layered on top of the autonomic and metabolic disruption.

Hormonal Disruption in Both Sexes

COVID-19 does not spare the endocrine system. In women, the virus can cause temporary ovarian dysfunction, leading to drops in estrogen that destabilize the hypothalamic thermostat in the same way menopause does. This is why even younger women can experience hot flashes after infection. The English clinic data showing 61% of 18-to-39-year-olds reporting hot flushes is consistent with this: the researchers noted that autonomic dysfunction and hormonal disruption both likely contribute to vasomotor symptoms in this age group, on top of other potential confounders like obesity and medications.¹

Men are not exempt from hormonal fallout. COVID-19 can damage testicular tissue and impair sperm production. Studies have found a decreased ratio of testosterone to other reproductive hormones in men who had COVID compared to age-matched healthy men.⁹ While testosterone drops in men are more commonly associated with fatigue, mood changes, and reduced libido, significant hormonal shifts can also affect thermoregulation. Men undergoing androgen deprivation therapy for prostate cancer, for example, frequently experience hot flashes. A COVID-related dip in testosterone could produce a milder version of the same effect.

The Overlap With Chronic Fatigue Syndrome

The symptom overlap between long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) has been recognized since early in the pandemic. Both conditions feature crushing fatigue, cognitive difficulties, exercise intolerance, and, relevant here, temperature dysregulation. Research has found that a specific temperature-sensing ion channel called TRPM3 is dysfunctional in both conditions. When researchers tested the function of this channel in post-COVID patients, ME/CFS patients, and healthy controls, the post-COVID group and the ME/CFS group showed virtually identical impairment, and both were significantly different from healthy people.¹⁰

TRPM3 channels are involved in calcium signaling and temperature sensing throughout the body. When they don’t work properly, the body’s ability to detect and respond to temperature changes goes haywire. This finding is significant for two reasons. First, it provides a molecular-level explanation for why post-COVID patients experience abnormal heat sensations that don’t correspond to any actual rise in core body temperature. Second, it links post-COVID hot flashes to a broader pattern of channelopathy (ion channel dysfunction) that may underpin many of the condition’s symptoms. For people who have had ME/CFS for years and experienced temperature dysregulation, the post-COVID research is validating: the same biological disruption appears to be at work.

What Actually Helps

Managing post-COVID hot flashes is frustrating because there is no single treatment that targets the root cause, in part because there are multiple root causes operating simultaneously. That said, several approaches have shown promise or at least reasonable rationale:

Antihistamines: If mast cell activation is driving flushing and sweating episodes, over-the-counter H1 and H2 blockers can reduce the intensity. Some long COVID clinics have adopted this as a first-line approach for patients with allergy-like symptoms alongside their hot flashes.
Evening carbohydrates: For night sweats specifically, having a small carbohydrate snack before bed may prevent the glycogen depletion and adrenaline surge cycle described above. The evidence is limited to a few case reports, but the intervention carries essentially no risk for non-diabetic individuals.
Cooling strategies: Layered clothing, fans, cooling pillows, and keeping the bedroom cold are basic but genuinely helpful. Hot flashes peak and resolve faster when you can dump heat quickly.
Autonomic rehabilitation: Gradual exercise programs designed for people with dysautonomia (such as the Levine protocol, originally developed for a related condition called POTS) can slowly retrain the autonomic nervous system. This is a months-long process, not a quick fix.
Hormonal assessment: If you are perimenopausal or menopausal and also dealing with post-COVID symptoms, it is worth having your hormone levels checked. COVID may have accelerated or worsened pre-existing hormonal shifts, and hormone therapy could address that component even if it does not resolve the post-viral autonomic issues.

What does not help much, at least based on the available evidence, is simply waiting it out without any intervention. While most post-COVID hot flashes do eventually diminish, “eventually” can mean months to years, and in the meantime, disrupted sleep from night sweats compounds fatigue, cognitive fog, and overall quality of life. Being proactive about symptom management, even with imperfect tools, tends to produce better outcomes than passive waiting.

When Hot Flashes During Acute COVID Are Just Fever

It is worth distinguishing between genuine hot flashes and the feeling of being hot because you have a fever. During acute COVID-19, the body raises its core temperature as part of the immune response. The chills-then-sweating cycle of a fever can feel a lot like hot flashes, but it is a fundamentally different process. Fever is the thermostat being deliberately turned up; hot flashes are the thermostat malfunctioning. During a fever, your temperature is genuinely elevated and your body alternates between feeling cold (as it tries to generate heat to reach the new set point) and feeling hot (as it overshoots or the set point drops back down). Hot flashes, by contrast, often occur without any measurable change in core temperature. The person feels burning hot and sweats profusely, but a thermometer reads normal.

If you are in the first week or two of a COVID infection and experiencing waves of heat followed by chills, that is most likely fever behavior. If you have recovered from the acute illness and are still getting sudden unprovoked episodes of flushing and sweating weeks or months later, particularly without a corresponding rise in body temperature, that is the post-viral hot flash phenomenon this article is about. Both are unpleasant, but they call for different responses. Fever responds to standard antipyretics and hydration. Post-viral hot flashes require the broader, multi-pronged approach described above.

A Symptom That Crosses Demographic Lines

Perhaps the most striking aspect of COVID-related hot flashes is how they cut across groups that would not normally be expected to experience them. Hot flashes have long been associated almost exclusively with menopause, and to a lesser extent with certain medications and medical treatments. COVID has essentially democratized the experience. Young women in their twenties, men, and people with no hormonal predisposition are reporting classic vasomotor symptoms after infection. The English post-COVID clinic data showing nearly identical hot flash rates across age groups from 18 to 65-plus is hard to explain through hormonal changes alone. The autonomic, inflammatory, and mast cell mechanisms described here account for why the symptom appears so broadly.¹

For clinicians, this means not dismissing hot flash complaints from demographics that don’t “fit the profile.” For patients, it means that if you are a 30-year-old man waking up drenched in sweat three months after COVID and feeling like something is deeply wrong, you are not imagining it, and you are not alone. The same biological disruptions that cause post-COVID fatigue and brain fog are, in many cases, the ones producing your hot flashes. They are part of the same syndrome, not a separate mystery.

1
IJID Regions. Menopause symptom prevalence in three post–COVID-19 syndrome clinics in England: A cross-sectional analysis
2
PubMed Central. Sleep disorders after COVID-19 in Czech population: Post-lockdown national online survey
3
F1000Research. Impact of evening carbohydrate intake on the resolution of persistent night sweats in patients with long COVID: a case series
4
MDPI (Biology). Imbalance of Peripheral Temperature, Sympathovagal, and Cytokine Profile in Long COVID
5
PubMed Central. Autonomic small fiber involvement in painful long COVID: a histological and clinical study
6
Nature / Scientific Reports. Brain temperature and free water increases after mild COVID-19 infection
7
PubMed Central. Immunological dysfunction and mast cell activation syndrome in long COVID
8
International Journal of Infectious Diseases. Mast cell activation symptoms are prevalent in Long-COVID
9
PubMed Central. COVID-19 Infections in Gonads: Consequences on Fertility?
10
PubMed Central. Transient receptor potential melastatin 3 dysfunction in post COVID-19 condition and myalgic encephalomyelitis/chronic fatigue syndrome patients