COVID-19 most commonly causes a sore throat, headache, fatigue, runny or stuffy nose, and cough. Symptoms typically appear 2 to 14 days after exposure. Most people experience what feels like a bad cold or mild flu, but the infection can also affect the gut, the nervous system, and other parts of the body in ways that set it apart from other respiratory illnesses.
The Most Common Symptoms
The symptoms you’re most likely to notice first are a sore throat, headache, and tiredness. A runny or stuffy nose is also very common. Cough, when it occurs, tends to be dry rather than productive. Fever shows up in some cases but not all, which can make COVID easy to dismiss early on.
Other frequently reported symptoms include muscle aches, sneezing, and shortness of breath. One hallmark that still distinguishes COVID from most other respiratory infections is a new loss of taste or smell, which can appear early and often without significant nasal congestion. This symptom is less common with newer variants than it was in 2020 and 2021, but it still occurs and is rare with colds or the flu.
Gut Symptoms Are More Common Than Many People Expect
Roughly half of people with a COVID infection experience some kind of digestive symptom. That can include nausea, vomiting, diarrhea, stomach pain, or loss of appetite. Research from the University of Nebraska Medical Center found the reported frequency of gastrointestinal symptoms ranged from 12% to 61% across studies, depending on the population and variant.
These gut symptoms happen because the virus can infect cells lining the digestive tract, not just the airways. About half of COVID patients shed viral genetic material in their stool, and that shedding correlates with more pronounced digestive problems. If your main symptoms are nausea and diarrhea without much of a cough, COVID is still worth considering.
How COVID Feels Different From a Cold or the Flu
COVID, colds, and the flu overlap enough to make it impossible to tell them apart by symptoms alone. But there are patterns worth knowing.
Cold symptoms appear faster, usually 1 to 3 days after exposure, and rarely cause fever, muscle aches, or significant fatigue. COVID takes longer to show up (2 to 14 days) and typically does cause tiredness and headache, which colds almost never do.
The flu is harder to distinguish. Both COVID and the flu cause headache, sore throat, fatigue, and a stuffy nose. The key differences: flu almost always brings a fever, while COVID sometimes doesn’t. Flu nearly always causes a cough, while COVID’s cough is more intermittent. And a sudden loss of taste or smell points strongly toward COVID. The flu rarely causes that.
The only reliable way to know which infection you have is a test. If you’re symptomatic, the FDA recommends testing immediately with a home antigen test and retesting if the first result is negative, since it can take 2 to 5 days (sometimes longer) after exposure for the virus to reach detectable levels.
Symptoms in Children
Children most commonly develop a fever and cough. Beyond that, kids may have a sore throat, runny nose, headache, fatigue, shortness of breath, or digestive symptoms like nausea, vomiting, and diarrhea. The challenge is that these symptoms look identical to dozens of other childhood infections, making it especially hard to identify COVID without testing.
During periods of high Omicron transmission, doctors noticed a notable increase in croup, the barking cough caused by swelling in the upper airway, in young children with COVID. This happened even as other viruses that typically cause croup were declining.
Emergency Warning Signs
Most COVID infections resolve on their own, but certain symptoms signal that the body is struggling in ways that need immediate medical attention. Call 911 if you or someone you’re caring for develops:
- Trouble breathing that goes beyond mild congestion
- Persistent chest pain or pressure
- New confusion or difficulty thinking clearly
- Inability to wake up or stay awake
- Color changes in the lips, nail beds, or skin, which may appear pale, gray, or blue depending on skin tone
These signs can indicate that oxygen levels are dropping or that the infection is affecting the heart or brain. They can develop even in people whose illness initially seemed mild.
When Symptoms Don’t Go Away: Long COVID
For most people, acute COVID symptoms clear within one to two weeks. But some people find that symptoms persist for weeks or months afterward, a condition known as long COVID. More than 200 symptoms have been linked to it, though the most commonly reported are fatigue, brain fog (difficulty thinking or concentrating), and post-exertional malaise, where symptoms flare up after even modest physical or mental effort.
Other long COVID symptoms span nearly every system in the body:
- Respiratory and heart: shortness of breath, cough, chest pain, heart palpitations
- Neurological: headaches, sleep problems, dizziness when standing, pins-and-needles sensations, changes in taste or smell, depression, anxiety
- Digestive: diarrhea, stomach pain, constipation
- Other: joint or muscle pain, rashes, changes in menstrual cycles
The defining feature of long COVID is that these symptoms interfere with daily life in a way the person wasn’t experiencing before their infection. Fatigue isn’t just feeling tired after a long day. It’s the kind that makes routine tasks feel overwhelming. Brain fog isn’t a momentary lapse. It’s persistent difficulty finding words, following conversations, or completing work you used to do without thinking.