Long COVID can produce symptoms across nearly every organ system, from persistent fatigue and brain fog to heart palpitations and shortness of breath. The condition is defined as symptoms lasting at least three months after a COVID-19 infection, and it affects an estimated 10% to 26% of adults who had COVID-19. Most people recover from acute COVID within four weeks, and many continue improving between weeks four and twelve, but for a significant minority, symptoms linger far longer.
Brain Fog and Cognitive Symptoms
Difficulty thinking clearly is one of the most reported long COVID symptoms, commonly called “brain fog.” This isn’t just occasional forgetfulness. Studies show that people with long COVID demonstrate measurable deficits in sustained attention, cognitive flexibility, and memory. In one large multicenter study, nearly 70% of long COVID patients reported concentration difficulty.
A particularly well-documented problem is slowed processing speed, meaning it takes longer to absorb information and respond to it. This can make conversations feel harder to follow, work tasks take longer, and reading feel unusually taxing. These cognitive changes correlate with structural and functional brain changes visible on imaging, which means the symptoms reflect real physiological disruption, not just stress or poor sleep.
Fatigue and Post-Exertional Malaise
Crushing fatigue is the single most common long COVID symptom, and it behaves differently from ordinary tiredness. Many people experience what’s called post-exertional malaise: a disproportionate worsening of symptoms after physical or mental effort that would have been manageable before. A short walk or a busy afternoon at work can trigger a “crash” lasting hours or days. This pattern overlaps significantly with chronic fatigue syndrome, and for some long COVID patients, the two conditions are essentially indistinguishable.
Heart Palpitations and Circulation Problems
Cardiovascular symptoms are among the most frequently reported, especially palpitations and shortness of breath. A subset of long COVID patients develop a condition called POTS (postural orthostatic tachycardia syndrome), where heart rate spikes by at least 30 beats per minute within ten minutes of standing up. This can cause lightheadedness, nausea, cognitive impairment, and near-fainting episodes.
Others develop an inappropriately fast resting heart rate, averaging above 90 beats per minute over a full day or exceeding 100 beats per minute on multiple occasions. These two cardiovascular patterns are distinct but can overlap. People with POTS tend to experience more presyncope (feeling like you’re about to faint), brain fog, and nausea, while those with a fast resting heart rate are more likely to have elevated blood pressure. In both cases, palpitations and breathlessness are the most common complaints.
Respiratory Symptoms
Persistent shortness of breath and cough can continue months after the initial infection, even in people whose acute illness was mild. Long COVID affects multiple organ systems, and the lungs are frequently involved. Some people notice breathlessness only with exertion, while others feel winded during everyday activities like climbing stairs or talking. For those who were hospitalized or spent time in intensive care, it can be difficult to separate long COVID lung effects from the broader damage of severe illness and prolonged bed rest.
Other Common Symptoms
Long COVID doesn’t confine itself to the brain, heart, and lungs. The condition can affect the kidneys, skin, joints, and digestive system. Commonly reported symptoms include:
- Body, muscle, and joint pain that persists without clear injury
- Sleep disturbances, including difficulty falling or staying asleep
- Stomach pain and digestive issues
- Headaches, often frequent and recurring
- Anxiety and mood changes
Most people with long COVID have symptoms affecting more than one body system, which is part of what makes the condition so disorienting. You might be dealing with brain fog, joint pain, and a racing heart simultaneously, with no single explanation tying them together.
Long COVID in Children and Teens
Children and adolescents get long COVID too, though their symptom profiles differ by age. An NIH-funded study found that about 20% of school-age children and 14% of adolescents with prior COVID infection met the threshold for long COVID.
In school-age children, the most common prolonged symptoms were headache (57%), trouble with memory or focusing (44%), trouble sleeping (44%), and stomach pain (43%). Body pain and daytime tiredness were also frequently reported. Adolescents showed a different pattern, with daytime tiredness and low energy dominating at 80%, followed by body, muscle, or joint pain (60%), headaches (55%), and trouble with memory or focusing (47%). Like adults, children experienced symptoms across nearly every organ system, and most had problems in more than one area.
Who Is at Higher Risk
Certain factors increase your chances of developing long COVID. Having multiple underlying health conditions raises risk, and the more conditions you have, the higher the risk climbs. Conditions linked to more severe COVID outcomes include diabetes, chronic kidney or liver disease, chronic lung disease, heart conditions, obesity, and immunocompromised states. The risk of severe illness also increases sharply with higher body mass index.
Older adults face the highest risk of severe acute COVID, and demographic factors like race, ethnicity, disability status, and access to healthcare also play a role. People who are immunocompromised may not be fully protected even when vaccinated, and may benefit from additional vaccine doses. Staying current with COVID-19 vaccination remains one of the most effective preventive measures, particularly for those with underlying conditions.
How Long COVID Is Diagnosed
There is currently no blood test or scan that can confirm long COVID. No validated biomarkers have been identified, and routine lab work, including blood counts, metabolic panels, and other standard tests, shows essentially no meaningful differences between people who developed long COVID and those who recovered normally. Diagnosis relies on a detailed medical history, a physical exam to understand your symptoms, and lab work primarily aimed at ruling out other causes. This can be frustrating, especially when test results come back normal despite significant symptoms.
Recovery Timeline
The trajectory varies widely. Many people improve gradually over months, but recovery is not always linear. Symptoms can follow a relapsing and remitting pattern, improving for weeks before flaring again. According to global estimates from the World Health Organization, about 15% of people with long COVID still have symptoms at 12 months. For some, the condition becomes a progressive or chronic illness affecting daily functioning for years. Others experience slow but steady improvement, particularly with pacing strategies, rehabilitation, and treatment of specific symptoms like POTS or sleep disruption.