COVID-19 symptoms typically appear 2 to 14 days after exposure and can range from barely noticeable to severe. The most common ones overlap heavily with cold and flu symptoms: fever or chills, cough, sore throat, runny or stuffy nose, body aches, fatigue, and headache. What has historically set COVID apart is a sudden loss of taste or smell, though this has become less common with newer variants.
The Most Common Symptoms
COVID-19 can affect nearly every system in the body, but the symptoms most people experience are respiratory and systemic. These include fever or chills, a dry or wet cough, sore throat, runny or stuffy nose, sneezing, shortness of breath, muscle pain or body aches, headache, and fatigue or general weakness.
Some people also develop gastrointestinal symptoms like nausea, vomiting, and diarrhea. These gut symptoms can actually show up before any fever or respiratory issues, which catches some people off guard. They may assume food poisoning or a stomach bug before a cough or sore throat ever develops.
Loss of taste or smell remains a hallmark of COVID, even though it occurs less frequently with current variants than it did in 2020 and 2021. When it does happen, the virus disrupts the function of smell-sensing neurons in the nose rather than directly infecting them. This distinction matters because it means most people recover their sense of smell over time, though for some it takes months. A subset of people develop parosmia, where familiar smells become distorted (coffee smelling like burnt rubber, for example).
Symptoms often start mild and can intensify over the first week. Not everyone progresses, but the pattern is common enough that feeling slightly better on day two doesn’t necessarily mean you’re in the clear.
How COVID Differs From a Cold or Flu
A common cold tends to stay in your nose and throat. The typical cold brings a sore throat, sneezing, runny nose, and a mild cough, but rarely fever, body aches, or significant fatigue.
The flu shares far more overlap with COVID. Both cause fever, chills, headache, muscle aches, fatigue, cough, sore throat, and congestion. Both can also cause vomiting, diarrhea, and shortness of breath. The key differences are subtle: COVID is more likely to cause a change in taste or smell, and flu symptoms tend to hit all at once rather than building gradually over several days. In practice, the overlap is significant enough that testing is the only reliable way to tell them apart. Symptoms can also vary based on which COVID variant is circulating and whether you’ve been vaccinated.
Symptoms in Children
Children are more likely to remain completely asymptomatic than adults. When they do develop symptoms, the presentation is generally the same: fever, cough, runny nose, sore throat, and fatigue. Gastrointestinal symptoms like vomiting and diarrhea tend to be more prominent in kids than in adults, which can make COVID look like a stomach illness rather than a respiratory one.
A rare but serious complication in children is multisystem inflammatory syndrome (MIS-C), which can develop weeks after infection. Signs include persistent high fever, abdominal pain, rash, red eyes, and unusual tiredness. This condition requires immediate medical attention.
Many Infections Cause No Symptoms at All
A large meta-analysis covering over 14,000 people found that roughly 44% of those who tested positive for SARS-CoV-2 never developed symptoms throughout their entire infection. The rate of asymptomatic infection varied dramatically by age. It peaked around age 13 to 14, where about 36% of infections were silent, then gradually decreased through adulthood. By age 90, only about 8% of infections were asymptomatic, which helps explain why older adults tend to have more noticeable and severe illness.
This is worth understanding because asymptomatic carriers can still spread the virus. If you’ve been exposed and feel fine, a test is more informative than how you feel.
Warning Signs That Need Immediate Attention
Most COVID infections resolve at home within one to two weeks. But certain symptoms signal that the illness is becoming dangerous. Difficulty breathing or persistent shortness of breath at rest is the most important red flag. Other warning signs include persistent chest pain or pressure, confusion or inability to stay awake, pale or blue-tinged lips or skin (a sign of low oxygen), and an inability to keep down fluids.
These symptoms can develop suddenly, sometimes after a period where the illness seemed to be improving. People over 65, those with chronic conditions like heart disease or diabetes, and immunocompromised individuals are at higher risk for this kind of progression.
Neurological Symptoms and Brain Fog
COVID can cause both acute and lasting changes in the brain. During the infection itself, many people report difficulty concentrating, mental fogginess, dizziness, and sensory disturbances beyond just losing smell. These aren’t just subjective complaints. Brain imaging studies have identified measurable structural changes in areas of the brain associated with cognition in people who’ve had COVID, and greater degrees of these changes correlate with worse cognitive performance.
For most people, the mental cloudiness lifts as the infection clears. But in a subset of patients, cognitive difficulties persist for months or longer, becoming part of the broader picture of long COVID.
When Symptoms Don’t Go Away: Long COVID
Long COVID is defined as symptoms persisting for more than three months after infection that can’t be explained by another diagnosis. The range of possible symptoms is remarkably wide: fatigue, shortness of breath, cough, chest pain, heart palpitations, dizziness, abdominal pain, diarrhea, headache, joint and muscle pain, cognitive impairment, insomnia, depression, anxiety, hair loss, menstrual irregularities, and erectile dysfunction have all been documented.
One of the defining features is post-exertional malaise, where physical or mental effort triggers a disproportionate crash in energy and worsening of symptoms. This is different from normal tiredness after exertion. People with this symptom often feel worse one or two days after activity rather than immediately.
Long COVID can develop after mild infections, not just severe ones. The cognitive symptoms, often called brain fog, can persist for more than a year in some people, with measurable effects on memory, attention, and processing speed. Smell disturbances that linger are associated with greater degrees of cognitive difficulty, suggesting the virus’s impact on the nervous system plays a central role in these lasting effects.