Long COVID and Dysautonomia

John Murphy, M.D., M.P.H., D.P.H., President, The COVID-19 Lonh-haul Foundation

Abstract: Long COVID (post-acute sequelae of SARS-CoV-2 infection, PASC) is increasingly recognized as a heterogeneous syndrome characterized by persistent fatigue, cognitive dysfunction, exercise intolerance, dyspnea, autonomic symptoms, sleep disturbance, pain, and neuropsychiatric manifestations. Dysautonomia has emerged as a major mechanistic and clinical axis within Long COVID, encompassing orthostatic intolerance, postural orthostatic tachycardia syndrome (POTS), inappropriate sinus tachycardia, vasovagal syncope, gastrointestinal dysmotility, sudomotor abnormalities, and impaired heart-rate variability (HRV). Current evidence suggests that autonomic dysfunction arises through a convergence of mechanisms including immune dysregulation, persistent inflammatory signaling, endothelial and microvascular injury, small-fiber neuropathy, baroreflex impairment, autoantibody-mediated receptor dysfunction, central autonomic network disruption, and possible vagus-nerve involvement. The vagus nerve occupies a particularly important position because it links autonomic regulation, inflammation, cardiopulmonary physiology, gastrointestinal function, and neuroendocrine signaling. This review synthesizes contemporary evidence on the etiology, pathology, physiology, history-and-physical (H&P) assessment, clinical manifestations, disease progression, and treatment strategies for Long COVID–associated dysautonomia, with special emphasis on vagal-neuroimmune mechanisms and emerging interventions such as transcutaneous vagus-nerve stimulation (tVNS).

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Introduction

Long COVID refers to persistent or new symptoms occurring after acute SARS-CoV-2 infection, typically lasting at least several weeks to months and not explained by an alternative diagnosis. Population studies have documented substantial long-term morbidity even after non-hospitalized infections, with fatigue, cognitive impairment (“brain fog”), orthostatic symptoms, palpitations, exercise intolerance, dyspnea, and sleep disturbance among the most common complaints. Dysautonomia has emerged as a recurrent phenotype across Long COVID cohorts, overlapping with conditions such as POTS and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

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The autonomic nervous system (ANS) regulates cardiovascular, respiratory, gastrointestinal, thermoregulatory, endocrine, and immune functions. Because autonomic control is distributed across the brainstem, vagus nerve, sympathetic ganglia, enteric nervous system, endocrine axes, and peripheral sensory networks, disruption at multiple levels can produce the diverse symptom spectrum observed in Long COVID.

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Etiology and Pathogenesis

Persistent immune activation and inflammatory signaling

Many patients with Long COVID exhibit evidence of ongoing immune perturbation months after acute infection, including altered cytokine profiles, activated immune-cell subsets, and inflammatory mediators. These signals may affect autonomic control through both central and peripheral pathways. The vagus nerve normally participates in the “cholinergic anti-inflammatory pathway,” in which vagal efferent signaling modulates inflammatory responses. Impairment of this pathway has been proposed as a contributor to persistent symptoms.

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Autoimmunity and receptor-targeting antibodies

Autoantibodies directed against G-protein–coupled receptors (GPCRs), including adrenergic and muscarinic receptors, have been reported in subsets of patients with POTS and Long COVID. These antibodies may alter autonomic signaling, vascular tone, and heart-rate regulation, although causality remains under investigation.

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Small-fiber neuropathy

Small unmyelinated and thinly myelinated fibers carry autonomic as well as sensory signals. Small-fiber injury can produce orthostatic intolerance, abnormal sweating, gastrointestinal dysmotility, neuropathic pain, and temperature dysregulation. Several Long COVID cohorts have demonstrated findings consistent with small-fiber neuropathy in at least a subset of patients.

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Endothelial dysfunction and microvascular injury

SARS-CoV-2 can affect vascular and endothelial pathways during acute infection, and persistent endothelial dysfunction has been proposed as a mechanism for impaired perfusion, exercise intolerance, and autonomic symptoms. Microvascular abnormalities may interact with autonomic dysfunction by impairing cerebral and peripheral blood-flow regulation.

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Central autonomic network involvement

The central autonomic network includes the nucleus tractus solitarius (NTS), dorsal motor nucleus of the vagus, hypothalamus, insula, amygdala, anterior cingulate cortex, and brainstem autonomic nuclei. Neuroinflammation, altered connectivity, or injury within these regions could contribute to dysautonomia, fatigue, cognitive dysfunction, and neuropsychiatric symptoms.

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Vagus Nerve: Anatomy, Physiology, and Long-COVID Implications

The vagus nerve (cranial nerve X) provides extensive parasympathetic innervation to the heart, lungs, gastrointestinal tract, liver, pancreas, and other organs. Approximately 80% of its fibers are afferent, transmitting sensory information from visceral organs to the brainstem. Through the NTS and related circuits, vagal afferents influence autonomic balance, respiration, satiety, inflammation, mood, and neuroendocrine function.

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Potential consequences of vagal dysfunction in Long COVID

Cardiovascular

1. Reduced parasympathetic (vagal) tone
2. Resting tachycardia or exaggerated heart-rate responses
3. Impaired baroreflex sensitivity
4. Orthostatic intolerance and POTS-like syndromes

Respiratory

1. Abnormal respiratory control and dyspnea
2. Hyperventilation tendencies in some patients
3. Reduced heart-rate variability linked to breathing patterns

Gastrointestinal

1. Nausea, early satiety, bloating
2. Altered gastric emptying
3. Constipation or diarrhea
4. Enteric nervous system dysregulation

Neurocognitive & endocrine-immune

1. Impaired cholinergic anti-inflammatory signaling
2. Interaction with the hypothalamic-pituitary-adrenal (HPA) axis
3. Fatigue, cognitive impairment, and stress-response abnormalities

Vagal dysfunction could affect cardiovascular, respiratory, gastrointestinal, neurocognitive, and endocrine-immune domains through reduced parasympathetic tone, impaired baroreflexes, altered respiratory control, enteric dysregulation, and disrupted cholinergic anti-inflammatory signaling.

Vagal dysfunction has been hypothesized to reduce anti-inflammatory signaling and mitochondrial efficiency, potentially amplifying fatigue, cognitive symptoms, and autonomic instability.

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Effects on hormones and neuroendocrine systems

Because vagal afferents communicate with the hypothalamus and brainstem, vagal dysfunction may influence stress-hormone regulation, appetite signaling, glucose homeostasis, and other endocrine processes. Proposed effects include altered cortisol dynamics, disrupted autonomic–immune–endocrine coupling, and changes in satiety and metabolic signaling, although these relationships remain incompletely defined.

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Clinical Phenotypes of Long-COVID Dysautonomia

Common manifestations include:

Typical symptom clusters

Orthostatic symptoms

1. Lightheadedness on standing
2. Palpitations
3. Presyncope or syncope
4. Excessive fatigue after upright posture

Cardiovascular dysautonomia

1. POTS-like tachycardia
2. Inappropriate sinus tachycardia
3. Blood-pressure variability
4. Reduced exercise tolerance

Sudomotor and thermoregulatory

1. Heat intolerance
2. Cold intolerance
3. Excessive sweating
4. Abnormal sweating patterns

Gastrointestinal and neurocognitive

1. Nausea and bloating
2. Constipation or diarrhea
3. Early satiety
4. Brain fog and impaired concentration
5. Sleep disturbance

Long-COVID dysautonomia often presents as overlapping orthostatic, cardiovascular, sudomotor, thermoregulatory, gastrointestinal, and neurocognitive symptom clusters.

Long-COVID dysautonomia frequently overlaps with ME/CFS-like post-exertional malaise and impaired recovery after physical or cognitive exertion.

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History and Physical Examination (H&P) Collection

A structured H&P is essential because symptoms are multisystemic and often fluctuate. Key history elements include:

History

1. COVID timeline
   • Date and severity of acute infection.
   • Hospitalization, oxygen requirement, ICU stay.
   • Vaccination history and timing relative to symptoms.
2. Autonomic symptoms
   • Dizziness, presyncope, syncope.
   • Palpitations and heart-rate awareness.
   • Orthostatic intolerance and inability to stand for prolonged periods.
   • Temperature intolerance and sweating abnormalities.
3. Exercise and recovery
   • Post-exertional symptom exacerbation.
   • Recovery time after activity.
   • Triggers such as heat, dehydration, or prolonged standing.
4. Neurologic and cognitive symptoms
   • Brain fog, memory difficulty, headache.
   • Paresthesias, neuropathic pain, sleep disturbance.
5. Gastrointestinal symptoms
   • Nausea, bloating, early satiety, altered bowel habits.
6. Medications and comorbidities
   • Beta-blockers, stimulants, antidepressants, antihypertensives.
   • Diabetes, autoimmune disease, thyroid disease, prior dysautonomia.

Physical examination

1. Supine and standing heart rate and blood pressure (active stand test).
2. Assessment for orthostatic tachycardia or hypotension.
3. Cardiac and pulmonary examination.
4. Neurologic examination including sensory testing and reflexes.
5. Skin examination for color changes, edema, and sweating abnormalities.
6. Volume status assessment.

Formal autonomic testing may include tilt-table testing, HRV analysis, Valsalva maneuver, deep-breathing tests, sudomotor testing, and quantitative sensory testing. Recent studies have documented abnormalities in standing responses, HRV, and baroreflex-related measures in Long COVID cohorts.

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Pathology and Physiology

Autonomic imbalance

A recurring finding is reduced parasympathetic activity and/or excessive sympathetic activation, reflected by impaired HRV and exaggerated heart-rate responses. Reduced respiratory sinus arrhythmia and abnormal Valsalva responses have been observed in some Long COVID patients.

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Baroreflex impairment

Baroreceptors maintain blood-pressure stability during postural change. Impaired baroreflex sensitivity can contribute to orthostatic tachycardia, dizziness, and exercise intolerance.

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Neuroimmune dysregulation

Vagal afferent signaling normally helps coordinate immune responses. Disruption of vagal pathways may weaken anti-inflammatory regulation, contributing to persistent symptoms.

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Microvascular and mitochondrial considerations

Impaired tissue perfusion, endothelial dysfunction, and altered cellular energy metabolism have been proposed as contributors to fatigue and exercise intolerance, though the relative importance of each mechanism remains under investigation.

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Disease Progression and Prognosis

Long COVID follows heterogeneous trajectories. Some patients improve gradually over months, while others experience persistent or relapsing symptoms. Orthostatic intolerance, fatigue, and cognitive symptoms may fluctuate with activity level, stress, infection, heat exposure, and sleep quality. Longitudinal studies suggest that a substantial proportion of symptomatic individuals remain symptomatic at one year or longer.

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Risk factors for prolonged symptoms are still being clarified but may include greater acute illness burden, female sex, preexisting autonomic vulnerability, autoimmune predisposition, and repeated infections.

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Treatment Strategies

Nonpharmacologic foundations

Volume expansion

1. Adequate hydration
2. Increased dietary sodium when appropriate
3. Monitor contraindications such as heart failure or kidney disease

Compression & orthostatic countermeasures

1. Waist-high compression garments
2. Compression stockings
3. Physical counter-maneuvers during prodromal symptoms

Activity pacing

1. Avoid boom-bust cycles
2. Respect post-exertional malaise
3. Use individualized energy management

Physical rehabilitation

1. Begin with recumbent or semi-recumbent exercise
2. Gradually progress as tolerated
3. Reduce early orthostatic stress

Initial management usually emphasizes hydration, sodium and volume support, compression garments, pacing, and carefully titrated rehabilitation before considering medications.

These approaches are commonly recommended for orthostatic intolerance and POTS-like presentations and should be individualized to symptom pattern and comorbidities.

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Pharmacologic management

Evidence remains limited and largely extrapolated from POTS and dysautonomia literature. Depending on the phenotype, clinicians may consider:

Strategy	Potential role
Beta-blockers	Reduce tachycardia and palpitations.
Ivabradine	Heart-rate control in selected patients.
Fludrocortisone	Volume expansion for orthostatic intolerance.
Midodrine	Increase vascular tone for orthostatic hypotension.
Pyridostigmine	Enhance parasympathetic signaling in some dysautonomia phenotypes.
Neuropathic pain agents	Target small-fiber neuropathy symptoms.

Therapy should be individualized and monitored for adverse effects. Current reviews emphasize that high-quality randomized evidence for Long COVID dysautonomia remains limited.

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Vagus-nerve–targeted interventions

Interest in vagus-nerve stimulation has increased because of its potential effects on autonomic balance, inflammation, pain, mood, and cognition. Non-invasive transcutaneous vagus-nerve stimulation (tVNS) stimulates auricular branches of the vagus nerve through the skin of the ear. Early pilot studies have reported improvements in some Long COVID symptoms, including fatigue and autonomic complaints, but the evidence remains preliminary and requires confirmation in larger randomized trials.

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What is known about vagus-nerve stimulation (VNS)?

Domain	Current evidence
Mechanistic rationale	May increase parasympathetic tone and engage the cholinergic anti-inflammatory pathway. pmc.ncbi.nlm.nih.gov+1
Pilot studies	Small studies have reported symptom improvement in subsets of Long COVID patients. pmc.ncbi.nlm.nih.gov+1
Ongoing trials	Randomized and sham-controlled studies are underway. VNS for Long-COVID-19
Clinical takeaway	Promising but not yet established as standard care; larger trials are needed before routine recommendation. VNS for Long-COVID-19+1

Vagus-nerve stimulation is biologically plausible and under active investigation, but it should currently be viewed as an emerging rather than established therapy.

Because VNS is not yet standard therapy for Long COVID, clinicians should frame it as investigational and consider trial enrollment when appropriate.

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Vagal Dysfunction and Organ-System Effects

Cardiovascular

• Reduced vagal tone can increase resting heart rate and decrease HRV.
• Impaired baroreflexes may contribute to orthostatic tachycardia and blood-pressure instability.
• Patients may experience palpitations, chest discomfort, and exercise intolerance. jacc.org+1

Respiratory

• Vagal pathways influence airway tone, respiratory rhythm, and reflexes.
• Dysregulation may contribute to dyspnea, abnormal breathing patterns, and hyperventilation in some patients. pmc.ncbi.nlm.nih.gov+1

Gastrointestinal

• The vagus nerve coordinates gastric motility, secretion, and gut-brain signaling.
• Symptoms may include nausea, bloating, early satiety, reflux, constipation, or diarrhea. clinicalmicrobiologyandinfection.org+1

Neuroendocrine and immune

• Vagal signaling interacts with the hypothalamus and HPA axis.
• Disruption may alter stress responses, sleep regulation, appetite, and inflammatory control. mdpi.com+1

Diagnostic Challenges

Long COVID lacks a single diagnostic biomarker. Dysautonomia can be intermittent and may not be captured during a brief clinic visit. Symptom overlap with anxiety disorders, deconditioning, cardiac disease, endocrine disorders, and primary autonomic disorders requires careful evaluation. Objective measures such as orthostatic vital signs, tilt-table testing, HRV analysis, and validated symptom questionnaires can improve diagnostic confidence.

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Future Directions

Key research priorities include:

1. Defining biologically distinct Long COVID subtypes.
2. Clarifying the role of viral persistence versus immune dysregulation.
3. Identifying validated biomarkers of autonomic dysfunction.
4. Determining the prevalence and significance of autoantibodies.
5. Establishing evidence-based pharmacologic and rehabilitation protocols.
6. Conducting adequately powered randomized trials of vagus-nerve stimulation and other neuromodulatory therapies. VNS for Long-COVID-19+2

Conclusion

Long COVID–associated dysautonomia represents a clinically significant and mechanistically complex disorder involving autonomic, immune, vascular, neurologic, and endocrine systems. Current evidence supports a multifactorial model that includes autonomic imbalance, baroreflex dysfunction, small-fiber neuropathy, immune dysregulation, and possible vagal-pathway impairment. The vagus nerve occupies a central position linking inflammation, cardiovascular control, respiration, gastrointestinal function, and neuroendocrine signaling, making it an attractive but still investigational therapeutic target. Evaluation requires a structured history, orthostatic assessment, and selective autonomic testing. Management currently relies on symptom-directed strategies—hydration, salt loading when appropriate, compression garments, pacing, tailored rehabilitation, and selected medications—with emerging interest in non-invasive vagus-nerve stimulation. While substantial progress has been made, rigorous mechanistic studies and randomized clinical trials remain essential to define causal pathways and establish effective treatments.

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Selected References

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2. Dani M, et al. Autonomic dysfunction in ‘long COVID’: rationale, physiology and management strategies. Clin Med (Lond). 2021. pmc.ncbi.nlm.nih.gov
3. Davis HE, et al. Long COVID: major findings, mechanisms and recommendations. Nat Rev Microbiol. 2023. nature.com
4. Keller C, et al. Association of Autonomic Dysfunction With Long COVID. J Am Coll Cardiol. 2026. jacc.org
5. Tamariz L, et al. Dysautonomia in Long COVID is Prevalent and Could Explain Many Symptoms. 2026. pmc.ncbi.nlm.nih.gov
6. Barizien N, et al. Clinical characterization of dysautonomia in long COVID-19. Sci Rep. 2021. nature.com
7. Zheng ZS, et al. Transcutaneous vagus nerve stimulation improves Long COVID symptoms. Front Neurol. 2024. pmc.ncbi.nlm.nih.gov+1
8. Khan MWZ, et al. Vagal nerve stimulation for the management of long COVID symptoms. 2024. pmc.ncbi.nlm.nih.gov+1
9. ClinicalTrials.gov. VNS for Long-COVID-19 (NCT05630040). VNS for Long-COVID-19
10. Popa E, et al. Molecular mechanisms of cognitive dysfunction in Long COVID. Int J Mol Sci. 2025. mdpi.com