COVID sweat is the informal name people give to episodes of excessive, unexplained sweating that occur during or after a SARS-CoV-2 infection. It can show up as drenching night sweats, sudden daytime flushing, or a persistent clamminess that lingers for weeks or months after the acute illness has passed. The phenomenon is more common than most people realize, and the reasons behind it extend well beyond the ordinary fever-and-chill cycle of a typical respiratory infection.
How Common Is Sweating During and After COVID
Sweating abnormalities show up frequently in studies of COVID-19 patients. A narrative review of dysautonomia in COVID patients found that roughly 17% of those studied reported sweating abnormalities, alongside other autonomic symptoms like palpitations, temperature intolerance, and labile blood pressure.1Frontiers in Neurology. Dysautonomia in COVID-19 Patients: A Narrative Review on Clinical Course, Diagnostic and Therapeutic Strategies An early autonomic testing study found that 11% of post-COVID patients developed hyperhidrosis (excessive sweating) and that more than a third had abnormal sudomotor function, which is the nerve-driven system that controls your sweat glands.2PubMed Central. Autonomic dysfunction following COVID-19 infection: an early experience
Night sweats specifically appear to be one of the more persistent sleep-related complaints. A large Czech national survey of people who had recovered from COVID-19 found that 38.4% reported night sweats, making it the second most common sleep disorder after insomnia. The survey also found that excessive sweating during sleep was more common in women and in older adults, and that for most people the symptom persisted for three months or longer.3PubMed Central. Sleep disorders after COVID-19 in Czech population: Post-lockdown national online survey Those numbers are striking when you consider that night sweats in the general population are far less frequent and usually linked to specific conditions like menopause or lymphoma.
The Fever Response Is Only Part of the Story
During an acute infection, sweating is a normal part of the body’s thermoregulatory response. When your immune system detects a pathogen, it raises your internal temperature set point, and sweating kicks in as the fever breaks to cool you back down. Most respiratory infections produce this pattern. COVID can too, and in at least one documented case, night sweats appeared as the very first symptom of COVID pneumonia, before cough or fever had developed.4Inflammation and Cell Signaling. COVID-19 pneumonia with night sweat as the first symptom
But the sweating that puzzles both patients and clinicians is the kind that continues long after the virus is gone. In these cases, the problem is not a fever breaking. The body’s sweat-regulation system itself has been disrupted. Understanding how requires looking at the autonomic nervous system, the network that runs sweating, heart rate, blood pressure, digestion, and other functions you never have to think about.
Autonomic Dysfunction After COVID
The autonomic nervous system has two major branches: the sympathetic branch, which ramps the body up (fight-or-flight responses, increased heart rate, sweating), and the parasympathetic branch, which calms things down. After COVID, many patients develop a condition broadly called dysautonomia, where this system stops working in a coordinated way. Symptoms can include dizziness, rapid heart rate, exercise intolerance, gastrointestinal problems, brain fog, and sweating.5PubMed Central. Autonomic Dysfunction Related to Postacute SARS-CoV-2 Syndrome
One well-recognized form of post-COVID dysautonomia is Postural Orthostatic Tachycardia Syndrome, or POTS, where standing up triggers an abnormal spike in heart rate. A prospective study of post-COVID patients found that sudomotor dysfunction was one of the most affected domains on standardized autonomic testing, alongside orthostatic intolerance and gastrointestinal problems.6PubMed Central. Autonomic dysfunction in post-COVID patients with and without neurological symptoms: a prospective multidomain observational study A JAMA review noted that in 30% to 40% of POTS cases, symptoms began within three months of an infection such as COVID, Epstein-Barr virus, or influenza.7JAMA. Postural Orthostatic Tachycardia Syndrome (POTS): A Review
What makes post-COVID sweating different from, say, the sweating you get from nervousness or exercise is that it often comes without an obvious trigger. People report waking up with soaked sheets, or suddenly becoming drenched in the middle of a calm afternoon. The signals that normally tell sweat glands when and how much to activate are misfiring.
How the Virus Gets to the Nerves That Control Sweating
Researchers have proposed several mechanisms for how SARS-CoV-2 disrupts autonomic control. One pathway involves the virus directly invading the hypothalamus or the medulla, two brain regions that serve as central command for autonomic functions. The virus could reach these areas through nerves or through the bloodstream.8PubMed Central. Investigating the possible mechanisms of autonomic dysfunction post-COVID-19 The hypothalamus is the brain’s thermostat. If it gets inflamed or damaged, temperature regulation and sweating can go haywire.
Another pathway works from the outside in. The immune response to the virus triggers a wave of cytokines, signaling molecules that coordinate inflammation. In some people, this inflammatory response does not shut down properly after the infection clears. A review of cytokine-based pathophysiology in Long COVID proposed that this chronic low-grade inflammation activates brain immune cells called microglia, leading to ongoing neuroinflammation that produces fatigue, brain fog, and autonomic instability.9PubMed Central. A review of cytokine-based pathophysiology of Long COVID symptoms
Evidence of sympathetic overdrive has been directly measured. A study tracking electrodermal activity (a proxy for sympathetic nervous system output through the skin) found that Long COVID patients with sympathetic overactivity showed heightened readings, particularly during late nighttime hours.10PubMed Central. Characterization of sympathicotonia in post-covid condition (long covid) and healthy controls using long-term electrodermal activity (EDA) follow-up That timing lines up with what patients describe: being jolted awake by soaking-wet sheets in the middle of the night, with their heart pounding, even though the room is cool.
Small Fiber Neuropathy and Damage to Sweat Glands
The nerves that control sweat glands are small fibers, thin nerve endings distributed throughout the skin. Mounting evidence shows that COVID can damage these fibers directly. A study comparing Long COVID patients to healthy controls found significant reductions in the nerve fiber density around sweat glands, even in patients whose standard nerve fiber tests came back normal.11PubMed Central. Autonomic small fiber involvement in painful long COVID: a histological and clinical study In other words, specialized testing can reveal nerve damage around sweat glands that routine screening misses.
This type of damage, called small fiber neuropathy (SFN), has been confirmed in skin biopsies of Long COVID patients. One study found SFN present in about 63% of Long COVID patients tested, alongside widespread autonomic failure in roughly 89% of the group. The same study noted extensive overlap between Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), with both conditions showing similar rates of autonomic problems and small fiber damage.12PLOS ONE. Shared autonomic phenotype of long COVID and myalgic encephalomyelitis/chronic fatigue syndrome
A separate comparison study also found autonomic dysfunction and SFN in both post-COVID patients and ME/CFS patients, with about a fifth of post-COVID patients showing abnormal sweat gland function on standardized testing.13PubMed Central. Dysautonomia and small fiber neuropathy in post-COVID condition and Chronic Fatigue Syndrome The consistent finding across multiple research groups is clear: COVID can physically damage the tiny nerves responsible for sweat regulation, and this damage may be part of a broader pattern shared with other post-viral conditions.
Perhaps the most striking finding came from a study that compared autonomic testing results before and after COVID-19 infection in the same patients. Every participant in the study showed worsened sudomotor function after their infection, including those who had had normal results previously.14eNeurologicalSci. Demonstrating new-onset or worsened sudomotor function post-COVID-19 on comparative analysis of autonomic function pre-and post-SARS-CoV-2 infection That before-and-after design is valuable because it removes ambiguity about whether the dysfunction existed before the infection.
Mast Cell Activation and the Histamine Connection
Another piece of the puzzle involves mast cells, immune cells that release histamine and other inflammatory chemicals. A study of Long COVID patients found that their symptom scores on a mast cell activation questionnaire rose significantly after COVID-19 and were statistically indistinguishable from scores of patients who had been diagnosed with mast cell activation syndrome (MCAS) before the pandemic. Severity increased for virtually every symptom measured.15PubMed Central. Mast cell activation symptoms are prevalent in Long-COVID
Mast cell activation can cause flushing, hives, and excessive sweating because histamine dilates blood vessels and stimulates sweat glands. For some Long COVID patients, the sweating episodes come paired with skin flushing, itching, or gastrointestinal symptoms, a cluster that points toward mast cells being involved. This has led some clinicians to trial antihistamines and mast cell stabilizers in patients with persistent post-COVID sweating, though large controlled trials are still lacking.
Spike Protein Found in Sweat Glands
One intriguing case report found SARS-CoV-2 spike protein in the eccrine sweat glands and the acrosyringium (the sweat duct opening at the skin surface) of a patient who developed repetitive miliaria-like skin lesions following mRNA vaccination.16PubMed. SARS-CoV-2 spike protein found in the acrosyringium and eccrine gland of repetitive miliaria-like lesions in a woman following mRNA vaccination Miliaria, commonly known as heat rash, occurs when sweat ducts become blocked. This single case does not prove that spike protein routinely lodges in sweat glands and causes widespread sweating problems. But it does suggest that the sweat glands themselves can be a target tissue, not just an innocent bystander being misdirected by faulty nerve signals. Whether viral persistence in or near sweat glands contributes to chronic sweating symptoms in a broader population remains an open question.
Does COVID Actually Change the Composition of Sweat
Beyond producing more sweat, there is evidence that COVID may change what is in the sweat. Researchers analyzing sweat samples from SARS-CoV-2-positive patients using gas chromatography found significant differences in the volatile compounds compared to uninfected people. Certain fatty acids like hexadecanoic acid were elevated in positive patients, while other compounds including squalene (a lipid normally found on skin) and undecanal (an aldehyde) were lower.17Scientific Reports. Solid-phase microextraction of sweat components of patients positive for Sars-Cov-2 for identification of possible biomarkers
A separate analysis identified fourteen metabolites in sweat that differed between positive and negative groups, including compounds like p-cymene and linalool. The researchers hypothesized that SARS-CoV-2 infection disrupts the metabolism of volatile compounds in sweat, or alters the skin microbiome in ways that change the volatile profile.18Journal of Chromatography Open. Identification of coronavirus disease marker compounds in sweat with comprehensive two dimensional gas chromatography using multiloop splitter-based non-cryogenic artificial trapping modulation system This research is driven partly by the idea that sweat could serve as a non-invasive diagnostic tool for COVID detection. But for patients who report that their sweat smells different after COVID, these findings offer a possible biochemical explanation.
What Can Help With Persistent COVID Sweating
Managing post-COVID sweating is tricky because it often sits inside a larger cluster of autonomic symptoms. A multidisciplinary approach tends to work better than targeting sweating alone. Nonpharmacologic strategies include increasing fluid and salt intake (which helps with blood volume and orthostatic stability), wearing moisture-wicking fabrics to bed, keeping bedroom temperatures cool, and avoiding alcohol and spicy foods close to bedtime. Graduated exercise programs, built up very slowly to avoid triggering post-exertional malaise, can help retrain the autonomic nervous system over time.5PubMed Central. Autonomic Dysfunction Related to Postacute SARS-CoV-2 Syndrome
On the pharmacologic side, clinicians sometimes prescribe medications aimed at the underlying autonomic dysfunction, such as beta-blockers for elevated heart rate, fludrocortisone to expand blood volume, or midodrine to stabilize blood pressure. For patients whose sweating appears linked to mast cell activation, antihistamines like cetirizine or famotidine have been tried anecdotally with mixed results. None of these approaches have been tested in large, rigorous trials specifically for post-COVID sweating, so treatment is largely guided by experience with other dysautonomia conditions.
One small case series took a different angle entirely. Three Long COVID patients with persistent night sweats were asked to add an evening carbohydrate meal (gluten-free macaroni) to their dinners instead of skipping or eating a very light evening meal. All three experienced a progressive decline in nighttime sweating, with symptoms resolving completely within about a week.19F1000Research. Impact of evening carbohydrate intake on the resolution of persistent night sweats in patients with long COVID: a case series The logic behind the intervention relates to stabilizing overnight blood sugar, since hypoglycemia is a known trigger for sympathetic nervous system activation and sweating. Three patients is far too few to call this a treatment, but the finding is notable because the intervention is simple and low-risk. For someone soaking through sheets every night and running out of options, eating a reasonable carbohydrate-containing dinner is worth trying.
Why COVID Sweating Gets Overlooked
One reason post-COVID sweating does not get the attention it deserves is that sweating problems are often dismissed as anxiety. A patient who presents with palpitations, dizziness, and sweating after a viral illness can look a lot like a patient with panic attacks, especially if standard blood work and imaging come back normal. The diagnostic tools that can detect sudomotor dysfunction and small fiber neuropathy, such as quantitative sudomotor axon reflex testing, skin biopsies, and electrochemical skin conductance testing, are not available in most primary care offices. Without them, the physical basis for the sweating goes unrecognized.
There is also a tendency to categorize symptoms into neat buckets: respiratory, cardiac, neurological. Sweating falls awkwardly between multiple specialties. Dermatologists see sweat glands as their territory, but the underlying problem is neurological or immunological. Neurologists may test for large fiber neuropathy and miss the small fiber damage. Cardiologists may focus on the tachycardia and dismiss the sweating as incidental. The result is that many patients are told their sweating is “just stress” or “hormonal” without being evaluated for the autonomic dysfunction that the research consistently identifies.
The Overlap With Other Post-Viral Syndromes
Post-COVID sweating is not unique to SARS-CoV-2. Dysautonomia and small fiber neuropathy have been documented after Epstein-Barr virus, influenza, and other infections for decades. The comparison between Long COVID and ME/CFS is particularly telling. Studies have found strikingly similar rates of autonomic failure, small fiber neuropathy, and postural tachycardia syndrome in both populations.12PLOS ONE. Shared autonomic phenotype of long COVID and myalgic encephalomyelitis/chronic fatigue syndrome The sweating abnormalities in Long COVID may represent a well-established post-viral autonomic pattern that is now being studied more intensely because of the sheer number of people affected by SARS-CoV-2.
For patients, the practical takeaway from this overlap is twofold. First, if you developed unexplained sweating after COVID and your doctor is unfamiliar with post-COVID dysautonomia, clinicians who treat ME/CFS or POTS often have relevant experience. Second, the treatments that help with autonomic dysfunction in these other conditions, including salt loading, compression garments, sleep hygiene, and careful reconditioning, are the same ones that tend to help with post-COVID sweating. You do not necessarily need a COVID-specific protocol.
Whether COVID sweating eventually resolves on its own varies widely. Some people see improvement within a few months. Others are still dealing with it a year or more later, particularly those with confirmed small fiber neuropathy, where nerve regrowth is slow and unpredictable. Tracking symptoms with a simple diary, noting when sweating occurs, what time of day, whether it follows meals or exertion, and whether it correlates with other autonomic symptoms, can help both you and your clinician identify patterns and guide treatment decisions.