The NIH’s RECOVER study, one of the largest long COVID investigations ever funded, identified 12 signature symptoms that distinguish long COVID from other post-illness conditions. These findings, published in JAMA, form the basis of a scoring system designed to help clinicians diagnose what has been a frustratingly vague condition. Long COVID itself is defined by the World Health Organization as symptoms that develop within three months of a COVID-19 infection and persist for at least two months with no other explanation.
The 12 Symptoms
The RECOVER researchers analyzed thousands of patients to pinpoint which symptoms most reliably signal long COVID. The 12 that emerged are:
- Post-exertional malaise (a crash in energy and function after physical or mental effort)
- Fatigue
- Brain fog
- Dizziness
- Heart palpitations
- Loss of or change in smell
- Loss of or change in taste
- Chronic cough
- Chest pain
- Gastrointestinal symptoms (nausea, diarrhea, bloating, or abdominal pain)
- Thirst
- Abnormal movements (tremors or involuntary muscle activity)
These 12 symptoms feed into a scoring tool called the PASC score. But the researchers behind it stress that you can still have long COVID without fitting neatly into this list. Someone with symptoms not captured by the score still deserves treatment.
Post-Exertional Malaise: The Defining Feature
Of all 12 symptoms, post-exertional malaise (PEM) stands out as the most characteristic. It’s not ordinary tiredness. PEM means that even minor effort, whether that’s walking to the mailbox, attending a meeting, or doing light housework, can trigger a disproportionate crash that lasts hours or days. The WHO describes it as fatigue and worsening of symptoms following even minor physical or mental exertion, and it can impair a person’s ability to exercise, work, or handle daily activities.
PEM is what makes long COVID resemble myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and it’s the reason standard advice like “just push through it” or “exercise more” can backfire. Energy management, often called pacing, is the primary strategy: planning activities around your energy limits rather than trying to power past them.
Brain Fog and Cognitive Problems
Brain fog is one of the most commonly reported and most disruptive long COVID symptoms. It’s a catch-all term for what researchers describe more precisely as deficits in attention, processing speed, memory, learning, and executive function. People with long COVID brain fog often struggle to follow conversations, find the right word, stay focused on tasks, or remember things that would have been automatic before their infection.
The underlying biology involves inflammation in the brain. The virus triggers immune cells in the central nervous system to release inflammatory molecules, which disrupt the blood-brain barrier, the protective lining that normally keeps harmful substances out of brain tissue. Once that barrier is compromised, more inflammatory signals leak in, damaging the neural circuits responsible for thinking clearly. Processing speed, the time it takes your brain to absorb and respond to information, appears to be one of the most consistently affected areas.
For management, the WHO conditionally recommends cognitive exercises and environmental modifications. Practical steps include breaking tasks into smaller pieces, using written reminders and checklists, and practicing diaphragmatic breathing to improve focus.
Heart Palpitations and Dizziness
Palpitations and dizziness often travel together in long COVID, and the connection points to a problem with the autonomic nervous system, the part of your nervous system that controls involuntary functions like heart rate, blood pressure, and digestion. When this system malfunctions, a condition called dysautonomia, your body struggles to regulate itself during ordinary activities like standing up from a chair.
One specific form that frequently appears after COVID is postural orthostatic tachycardia syndrome, or POTS. It’s defined as a heart rate increase of at least 30 beats per minute within 10 minutes of standing, and it can cause palpitations, chest pain, lightheadedness, and exercise intolerance. POTS was already the most common cardiovascular form of dysautonomia in young people before the pandemic, and numerous reports have now linked it directly to long COVID. The proposed mechanisms include low blood volume, inflammation, autoimmunity, and direct effects of the virus on nerves.
If you notice your heart racing or feel faint when you stand up, a simple test is to check your pulse lying down and then again after standing for a few minutes. A large jump is worth mentioning to your doctor.
Loss of Smell and Taste
Changes in smell and taste were among the earliest recognized COVID symptoms, and for some people they never fully return. In a prospective study of 88 patients who lost their sense of smell, about 80% recovered within the first two months. That still leaves roughly one in five dealing with persistent loss or distortion months or even years later.
The most evidence-backed approach to recovery is olfactory training: repeatedly sniffing a set of strong, distinct scents (commonly rose, eucalyptus, lemon, and clove) for 20 seconds each, twice a day. This process is slow, often taking months, but it helps retrain the damaged nerve pathways between your nose and brain.
Respiratory Symptoms
Chronic cough and shortness of breath reflect lingering damage or inflammation in the airways and lungs. For some people, imaging shows no visible lung damage, yet breathing still feels effortful, likely because of ongoing inflammation or dysfunction in the nerves that control breathing patterns.
Breathing exercises and pulmonary rehabilitation are the primary non-drug approaches. Nasal breathing (inhaling through your nose rather than your mouth) and body positioning adjustments can also help. The WHO recommends these techniques for patients who don’t experience worsening symptoms after exertion, since for those with post-exertional malaise, even breathing exercises need to be approached carefully.
Gastrointestinal Symptoms
Nausea, diarrhea, bloating, and abdominal pain appear on the list because the gut plays a surprisingly central role in long COVID. Research has found fragments of viral proteins circulating in the blood of people with ongoing symptoms, and the gut appears to be a key reservoir. Importantly, these are pieces of viral protein rather than active, replicating virus, but they’re enough to keep the immune system on alert.
Biopsy studies have found immune cells concentrated in areas of active intestinal inflammation, suggesting the gut lining remains inflamed long after the acute infection clears. This persistent gut disruption may actually drive symptoms beyond the digestive tract, contributing to the systemic inflammation that affects the brain, heart, and other organs. Dietary adjustments and probiotics are among the self-management strategies that may help, though evidence is still limited.
What Drives These Symptoms
No single mechanism explains all 12 symptoms, but several biological processes overlap. Viral persistence, where leftover viral proteins linger in tissues like the gut and throat, keeps the immune system activated long after the initial infection. This sustained immune response can lead to autoimmunity, where the body starts attacking its own tissues. One pathway involves the virus triggering antibodies that mistakenly target a protein found on the surface of blood vessels, potentially causing inflammation and tiny blood clots in the lungs, heart, and kidneys.
Other proposed drivers include hormonal imbalances, dysfunction in skeletal muscles, and problems with the complement system, a part of the immune response involved in clearing pathogens. These mechanisms aren’t mutually exclusive. A single patient might have viral protein fragments irritating the gut, autoimmune inflammation affecting blood vessels, and neuroinflammation clouding their thinking, all at the same time.
How Common Long COVID Is Now
As of 2023, about 6.4% of U.S. adults reported currently experiencing long COVID when surveyed by the CDC. That translates to roughly 16 million people. Vaccination before infection reduces the risk of developing long COVID by about 27%, based on a systematic review of 12 studies conducted by the European Centre for Disease Prevention and Control.
A 27% reduction is meaningful but far from complete protection. It means vaccination lowers your odds but doesn’t eliminate them, which is why long COVID continues to affect people even with widespread immunity from both vaccines and prior infections.
Managing Symptoms Day to Day
There is no single cure for long COVID, so management centers on addressing each symptom individually. For fatigue and post-exertional malaise, the core strategy is pacing: learning your energy limits and staying within them rather than pushing to the point of crashing. Good sleep hygiene, relaxation techniques, and a balanced diet support this approach.
For pain, standard over-the-counter options like ibuprofen or acetaminophen are generally recommended. Breathing exercises help with both respiratory symptoms and cognitive function. Psychological support and meditation can address the mood disorders that often accompany months of chronic illness. Antioxidant supplements and anti-inflammatory nutrients show some promise for reducing the baseline inflammation that underlies many of these symptoms, though the evidence base is still developing.
The most important principle across all 12 symptoms is avoiding the boom-and-bust cycle: doing too much on a good day, crashing, resting until you feel better, then overdoing it again. Consistent, moderate activity within your limits tends to produce better outcomes than alternating between overexertion and collapse.