Long COVID, also known as Post-COVID-19 Condition (PCC), is a chronic condition where symptoms persist or new ones develop for weeks, months, or even years after the initial SARS-CoV-2 infection.
As of early 2025, an estimated 6% of people who get COVID-19 develop this condition, affecting millions worldwide with a wide array of debilitating COVID symptoms.
This guide provides a comprehensive overview of Long COVID, from its complex symptoms and potential causes to diagnosis, management and the latest research, offering clarity on this enduring public health challenge.
Living with Long COVID can be an isolating experience, marked by persistent and often fluctuating symptoms.
In This Article
1. What Exactly is Long COVID? Defining the Condition
While the initial phase of COVID-19 is well-understood, its aftermath is proving to be a complex and persistent medical puzzle.
Long COVID is the umbrella term for the wide range of new, returning, or ongoing health problems that people can experience after being infected with the virus that causes COVID-19.
There is no single, universally accepted definition, but leading health organizations have established clinical criteria to help guide diagnosis and research.
- The World Health Organization (WHO) defines Post COVID-19 Condition as symptoms that usually start within 3 months of the initial illness, last for at least 2 months and cannot be explained by an alternative diagnosis. This definition, updated in February 2025, highlights the chronicity of the condition.
- The U.S. Centers for Disease Control and Prevention (CDC) describes Long COVID as a chronic condition occurring after SARS-CoV-2 infection that is present for at least 3 months. The CDC emphasizes that it is an infection-associated chronic condition that can affect one or more organ systems.
- The Mayo Clinic refers to it as post-COVID-19 syndrome, long-haul COVID, or PASC (post-acute sequelae of SARS-CoV-2). They note that while a universal definition is still evolving, it is characterized by symptoms that linger for months after the initial illness.
A key takeaway is that Long COVID is not simply a slow recovery.
It is a distinct clinical entity that can affect anyone who has had COVID-19, regardless of the severity of their initial infection—even those who were asymptomatic can develop it.
2. How Common is Long COVID in 2025?
Determining the exact prevalence of Long COVID is challenging due to evolving definitions, varying study methodologies and under-reporting.
However, data from 2024 and 2025 provide a clearer picture of its significant public health impact.
- Global Prevalence: The World Health Organization (WHO) estimated in early 2025 that approximately 6 in every 100 people (6%) who have had COVID-19 develop Post COVID-19 Condition. While the chance of developing it appears lower than earlier in the pandemic, the continued circulation of the virus means millions are still at risk with every new infection.
- U.S. Statistics: In 2024, about 17 million adults in the United States reported having Long COVID. This represents a significant portion of the population dealing with chronic COVID symptoms that impact their daily lives, including their ability to work.
- Varying Estimates: Some meta-analyses have reported higher figures. One analysis of 144 studies through May 2024 found a global pooled prevalence of 36%, though estimates varied widely. This variation underscores the complexity of capturing the true scope of the problem.
While the risk of developing Long COVID may have declined since the beginning of the pandemic, likely due to vaccination and changes in the virus, it remains a substantial and ongoing health crisis.
3. What Are the Most Common Long COVID Symptoms?
One of the most bewildering aspects of Long COVID is its sheer diversity of symptoms. Researchers have identified over 200 different symptoms affecting nearly every organ system.
These symptoms can be persistent, they can wax and wane, or new ones can appear long after the initial infection has resolved.
The CDC and other health organizations have categorized these lingering COVID symptoms to better understand and manage them.
| Category | Common Symptoms |
|---|---|
| General Symptoms | Overwhelming fatigue that interferes with daily life; Post-Exertional Malaise (PEM) or Post-Exertional Symptom Exacerbation (PESE): symptoms worsen after physical or mental effort; Fever (low-grade, intermittent) |
| Neurological Symptoms | Difficulty thinking or concentrating (“Brain Fog”); Headaches or chronic migraines; Sleep problems (insomnia, unrefreshing sleep); Dizziness or lightheadedness, especially upon standing (POTS); Pins-and-needles feelings (paresthesia); Changes in smell or taste; Depression or anxiety |
| Cardiopulmonary Symptoms | Difficulty breathing or shortness of breath (dyspnea); Persistent cough; Chest pain or tightness; Fast-beating or pounding heart (palpitations) |
| Musculoskeletal Symptoms | Joint pain; Muscle pain or aches (myalgia) |
| Digestive Symptoms | Diarrhea; Constipation; Stomach pain or bloating |
| Other Symptoms | Hair loss; Skin rashes; Changes in menstrual cycles |
Source: Compiled from CDC, WHO, and Mayo Clinic.
4. Why Does COVID-19 Cause Long-Term Symptoms?
The exact mechanisms behind Long COVID are still under intense investigation, but scientists have several leading theories.
It’s likely not one single cause, but a combination of factors that vary from person to person. At a 2025 Stanford Medicine symposium, experts outlined several compelling hypotheses.
Viral Persistence and Gut Reservoirs
One prominent theory is that the SARS-CoV-2 virus isn’t fully cleared from the body. It may hide in “reservoirs”, particularly in the gastrointestinal (GI) tract.
“The GI tract is more than just collateral damage. It may be a viral reservoir.”— Dr. John Gubatan, Gastroenterologist.
The gut’s abundance of ACE2 receptors—the virus’s entry point—may allow it to linger, causing chronic inflammation and disrupting the gut microbiome.
This could explain the high prevalence of GI issues and potentially trigger systemic problems.
Immune Dysregulation and Autoimmunity
The initial infection can throw the immune system into disarray. This can lead to two major problems:
- Autoimmunity: The immune system mistakenly attacks the body’s own tissues. Some Long COVID patients develop antiphospholipid antibodies, proteins that make blood more likely to clot. This suggests an autoimmune reaction, even if it doesn’t fit a classic autoimmune disease profile.
- Chronic Inflammation: The immune response remains “on” long after the virus is gone. A key culprit here are Neutrophil Extracellular Traps (NETs).
“These are sticky webs of DNA released by white blood cells to trap infections… in Long COVID they often stick around too long, clogging tiny blood vessels and causing ongoing inflammation.”— Dr. Beth Martin, Hematologist.
This persistent, low-grade inflammation and micro-clotting could explain symptoms like fatigue, brain fog and organ damage.
Endothelial and Neurological Damage
The virus is known to damage the endothelium, the inner lining of blood vessels.
This can impair blood flow and oxygen delivery throughout the body, affecting the heart, lungs and brain.
Furthermore, the virus can directly or indirectly affect the nervous system, including the vagus nerve, which controls many automatic bodily functions.
This could explain the rise in conditions like POTS and other forms of dysautonomia.
Mitochondrial Dysfunction
Emerging research points to problems with mitochondria, the “powerhouses” of our cells.
A study published in Nature Communications found that patients with Long COVID, especially those with post-exertional malaise, have significant abnormalities in their muscle tissue and impaired mitochondrial function.
This means their cells struggle to produce energy, providing a biological explanation for the profound fatigue they experience.
5. Who is Most at Risk for Developing Long COVID?
Anyone who gets COVID-19 can develop Long COVID, but studies have identified several factors that increase a person’s risk.
- Severity of Initial Illness: People who had severe COVID-19, especially those who were hospitalized or required intensive care, are at higher risk. However, it’s crucial to remember that many people with mild or even asymptomatic initial infections also develop Long COVID.
- Lack of Vaccination: The CDC and WHO both state that COVID-19 vaccination is the best available tool to prevent Long COVID. Studies show that vaccinated individuals who get a breakthrough infection are less likely to report long-term COVID symptoms.
- Demographics: Research consistently shows that women are diagnosed with Long COVID more often than men. The reasons are not fully understood but may relate to differences in immune responses.
- Pre-existing Conditions: Individuals with certain underlying health conditions, such as cardiovascular disease, diabetes, obesity, or autoimmune diseases, may be at higher risk.
- Repeat Infections: Each time a person is reinfected with SARS-CoV-2, they face a renewed risk of developing Long COVID.
6. How is Long COVID Diagnosed?
Diagnosing Long COVID is a significant challenge for both patients and clinicians, primarily because there is no single diagnostic test.
“There’s no confirmatory test, no single fix, and no specialty that fully owns this condition. It’s deeply frustrating for both patients and providers.”— Dr. Lauren Grossman, Integrative Medicine Specialist.
The diagnostic process is one of clinical evaluation and exclusion. A healthcare provider will:
- Take a Detailed Health History: This includes documenting the timing of the initial COVID-19 infection (if known) and the onset, nature, and fluctuation of current symptoms. A positive SARS-CoV-2 test is not required for a diagnosis, as many were infected before testing was widely available or had asymptomatic cases.
- Conduct a Physical Examination: A thorough physical exam helps assess overall health and identify specific signs related to the reported symptoms.
- Rule Out Other Conditions: Because Long COVID symptoms overlap with many other illnesses, providers will often run tests to exclude other potential causes. These may include:
- Routine blood tests (e.g., complete blood count, metabolic panel, thyroid function).
- Chest X-rays or CT scans to evaluate lung function.
- Electrocardiograms (ECGs) to check heart rhythm.
- Assess Functional Impact: A key part of the diagnosis is understanding how the symptoms affect a person’s daily life, including their ability to work, exercise and engage in social activities.
According to CDC guidance for clinicians, objective laboratory or imaging findings should not be the sole measure of a patient’s well-being, as many people with debilitating Long COVID have “normal” test results.
The patient’s reported experience is paramount.
7. What Are the Specific Syndromes Associated with Long COVID?
Within the broad spectrum of Long COVID, several distinct patterns or syndromes have emerged. Understanding these can help tailor management strategies.
Post-Exertional Symptom Exacerbation (PESE)
Also known as Post-Exertional Malaise (PEM), this is a hallmark symptom for many with Long COVID and is also characteristic of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS).
- Definition: PESE is the worsening of symptoms after even minor physical, cognitive, or emotional exertion.
- Triggers: Can be anything from a short walk or a trip to the grocery store to a mentally demanding work task or a stressful conversation.
- Delayed Onset: The “crash” can be delayed by 24-72 hours, making it difficult to connect the trigger with the effect.
- Impact: Recovery from a PESE crash can take days, weeks, or even months, and it can be profoundly disabling. Research has linked PESE to muscle abnormalities and metabolic disturbances, suggesting a clear biological basis.
“Brain Fog” and Cognitive Dysfunction
“Brain fog” is a non-medical term for a range of cognitive impairments that are among the most common and distressing Long COVID symptoms.
- Symptoms: Includes problems with short-term memory, difficulty concentrating, slowed processing speed and word-finding difficulties.
- Prevalence: Studies report that 60% or more of Long COVID patients experience brain fog.
- Impact: It can severely affect a person’s ability to perform at work or school and manage daily tasks. A study in The Lancet confirmed that Long COVID is associated with severe cognitive slowing.
Cardiopulmonary Issues and Dysautonomia
Heart and lung problems are frequent and can be frightening. They often stem from inflammation and dysfunction of the autonomic nervous system (dysautonomia).
- Common Symptoms: Shortness of breath (dyspnea), chest pain, and heart palpitations are widely reported.
- Postural Orthostatic Tachycardia Syndrome (POTS): A common form of dysautonomia seen in Long COVID. It’s characterized by a significant increase in heart rate upon standing, leading to lightheadedness, palpitations and fatigue.
- Underlying Causes: These symptoms can be caused by direct lung damage (fibrosis), inflammation of the heart muscle (myocarditis), or disruption of the nervous system signals that control heart rate and breathing.
8. How is Long COVID Treated and Managed?
Currently, there is no single cure for Long COVID. Treatment focuses on managing symptoms, improving quality of life and preventing symptom exacerbation.
A multidisciplinary, patient-centered approach is essential.
Symptom-Specific Management
- For Fatigue and PESE: The cornerstone of management is pacing. This involves carefully balancing activity and rest to stay within one’s “energy envelope” and avoid triggering a crash. Graded exercise therapy is often harmful and is not recommended for patients with PESE.
- For Brain Fog: Management may involve cognitive rehabilitation with speech therapists, lifestyle adjustments (e.g., using calendars, reducing multitasking), and addressing underlying contributors like poor sleep or nutritional deficiencies.
- For Migraines: Headache specialists may use a combination of lifestyle stabilization (consistent sleep, regular meals), preventive medications (including newer CGRP-targeting drugs), and acute treatments to manage attacks.
- For Smell Loss (Anosmia): Olfactory retraining, a therapy involving structured sniffing of essential oils, has shown promise. In clinical trials, this therapy, especially when combined with other treatments like platelet-rich plasma (PRP) injections, has helped patients regain their sense of smell.
Emerging Pharmaceutical and Holistic Approaches
Clinicians are exploring various medications and supplements to target the underlying mechanisms of Long COVID.
“One pharmaceutical showing real promise? Low-dose naltrexone (LDN). It’s been used in chronic fatigue and fibromyalgia for years, and we’re now finding that some Long COVID patients benefit at even higher doses.”— Dr. Lauren Grossman, Integrative Medicine Specialist.
Other targeted therapies may include magnesium for headaches, CoQ10 for mitochondrial support, and turmeric for inflammation.
However, it is crucial to work with a healthcare provider and avoid the “wild west” of unproven supplements.
A holistic assessment of diet, sleep, stress, and social connection is also a vital part of a comprehensive COVID treatment plan for long-haulers.
9. What Research is Being Done on Long COVID?
The global scientific community has mobilized to understand and combat Long COVID.
A major effort in the United States is the RECOVER Initiative (Researching COVID to Enhance Recovery), funded by the National Institutes of Health (NIH).
- Objective: RECOVER aims to learn about the long-term health effects of COVID by studying a large and diverse population of adults and children.
- Data Sharing: As of 2024, RECOVER has made de-identified data from thousands of participants available to researchers worldwide, accelerating the pace of discovery.
- Clinical Trials: The initiative is running multiple clinical trials to test the safety and effectiveness of potential treatments for Long COVID symptoms, including drugs, medical devices, and other therapies.
Beyond RECOVER, numerous universities and research consortia are investigating the pathophysiology of Long COVID, from immune dysregulation and viral persistence to neurological impacts, with the ultimate goal of developing effective diagnostic tools and targeted treatments.
10. How Do Long COVID Symptoms Compare to Long-Term Flu Effects?
While post-viral syndromes are not new—lingering fatigue and other symptoms can occur after influenza (the flu) or other infections—Long COVID appears to be distinct in its scale, severity and complexity.
- COVID vs Flu – Symptom Diversity: Long COVID is characterized by a much wider range of symptoms (over 200) affecting more organ systems than is typically seen post-flu. Neurological symptoms like severe brain fog, dysautonomia (POTS), and the loss of taste/smell are far more prominent and persistent in Long COVID.
- Prevalence and Duration: The prevalence of long-term symptoms appears to be significantly higher after COVID-19 compared to the flu. While most post-flu fatigue resolves within a few weeks or months, a substantial portion of Long COVID patients have symptoms lasting for years.
- Underlying Mechanisms: The proposed mechanisms for Long COVID, such as widespread micro-clotting, viral persistence in tissues, and significant autoimmune responses, seem more pronounced and complex than what is typically understood about post-influenza syndromes.
In short, while both viruses can cause post-viral issues, the evidence to date suggests that Long COVID represents a more severe, multi-systemic, and enduring public health challenge.
11. Living with Long COVID: Patient Experiences and Support
Beyond the clinical data and scientific theories are the millions of personal stories of lives altered by Long COVID.
Patients often describe a profound sense of loss—of their health, their careers, their social lives and their former selves.
Managing the mental health impact of Long COVID is a critical part of the recovery journey.
Many struggle with not only their physical COVID symptoms but also the emotional toll of a poorly understood illness.
They may face disbelief from family, employers, and even some healthcare professionals, leading to feelings of isolation and frustration.
“Managing the physical symptoms of long COVID is difficult enough, but the mental health impact is just as severe, made even more challenging due to the limited awareness and understanding of the condition.”— Shereen, a patient’s story from the Mental Health Foundation
Finding support is crucial. Connecting with others through patient-led support groups (online or in-person) can provide validation, practical advice and a sense of community.
Organizations like Long COVID Alliance, Body Politic, and Long COVID Europe offer valuable resources and advocacy for those navigating this challenging condition.
Frequently Asked Questions (FAQ)
1. What are the first signs of Long COVID?
There are no specific “first signs”. Long COVID is defined by symptoms that persist or appear weeks after the initial infection. The most commonly reported initial lingering symptoms are profound fatigue, shortness of breath, and cognitive issues like “brain fog”.
2. Can you get Long COVID if you were asymptomatic?
Yes. Anyone who has been infected with SARS-CoV-2 can develop Long COVID, even if they had a very mild case or no symptoms at all during the acute phase of the infection.
3. Is there a test for Long COVID?
No, there is no single diagnostic COVID test for Long COVID. Diagnosis is based on a clinical evaluation of your symptoms, your health history, and ruling out other medical conditions that could be causing your symptoms.
4. Is Long COVID contagious?
No. Long COVID itself is a post-viral condition and is not contagious. You cannot pass Long COVID to another person. However, you can still spread the SARS-CoV-2 virus if you have an active infection.
5. Does vaccination prevent Long COVID?
Vaccination is the most effective tool for preventing Long COVID. While it’s still possible to develop it after a breakthrough infection, studies show that being vaccinated significantly reduces the risk and severity of long-term symptoms.
6. How long does Long COVID last?
The duration varies greatly. For some, symptoms may improve over several months. For others, Long COVID can be a long-term chronic illness lasting for years. Recovery is often non-linear, with periods of improvement and relapse.
7. Can children get Long COVID?
Yes, children and adolescents can develop Long COVID, although it appears to be less common than in adults. Symptoms in children can include fatigue, headaches, and difficulty concentrating, which can impact their schooling and social development.
8. What should I do if I think I have Long COVID?
You should seek care from a healthcare provider. Keep a detailed log of your symptoms, when they started, and what makes them better or worse. This information will be crucial for your provider to make an assessment.
Conclusion
Five years into the pandemic, Long COVID has emerged as a formidable and lasting consequence of COVID-19.
It is a complex, multi-system illness that defies easy explanation and requires a compassionate, individualized approach to care.
While there is no magic bullet, significant progress is being made in understanding its underlying causes, identifying risk factors, and developing effective management strategies for its diverse COVID symptoms.
The most powerful tools we have are prevention through vaccination, listening to patients and supporting robust scientific research.
If you are struggling with lingering symptoms after a COVID-19 infection, know that you are not alone and that help is available.
Take the next step: If this guide has been helpful, please consider sharing it with others who may be seeking answers. If you have personal experience with Long COVID, sharing your story in the comments below (if applicable) can help build a community of support and understanding.
Medical Disclaimer
The information provided in this article is for informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read here.