COVID-19 can cause symptoms across nearly every organ system, from the familiar fever and cough to less expected signs like skin rashes and digestive problems. Most people develop symptoms within 3 to 5 days of exposure, though the incubation period can stretch up to 14 days. Over 200 distinct symptoms have been linked to the virus when you include both the acute infection and its longer-term aftermath.
The Most Common Symptoms
The symptoms most people associate with COVID-19 are respiratory and systemic. These overlap heavily with the flu and other respiratory viruses, which is why testing is the only reliable way to confirm a diagnosis. The CDC lists the core symptoms as:
- Fever or chills
- Cough
- Shortness of breath or difficulty breathing
- Fatigue
- Muscle or body aches
- Sore throat
- Runny or stuffy nose
- Headache
Not everyone gets all of these, and the combination varies from person to person. Some people run a high fever for days while others never spike a temperature at all. Fatigue is one of the most persistent complaints, often lingering well after other symptoms have cleared.
Loss of Taste and Smell
A sudden loss of taste or smell became one of COVID-19’s signature symptoms early in the pandemic. While this can happen with other respiratory infections, it occurs far more frequently with COVID-19 than with the flu. Among patients who lose their sense of smell, about 68% experience a complete loss rather than just a partial dulling. The rest notice their sense of smell is distorted, where familiar things smell wrong or different.
For most people, these senses return within a few weeks. But some experience lasting dysfunction. In one study, roughly 14% of patients who lost their sense of smell during the initial infection still couldn’t correctly identify common odors on follow-up testing, even after they felt recovered.
Digestive Symptoms
About a third of COVID-19 patients show up with gastrointestinal symptoms as their primary complaint, sometimes without any cough or congestion at all. The main digestive symptoms are diarrhea, nausea, and vomiting. This matters because people experiencing only stomach problems may not immediately suspect COVID-19, potentially delaying testing and isolation.
There’s evidence that the virus can establish itself in the gut before it shows up in the respiratory tract. That means digestive symptoms can actually precede the more recognizable signs like cough and fever by a day or more. Diarrhea linked to COVID-19 is typically watery and may come on suddenly.
Skin Rashes and “COVID Toes”
Skin symptoms are less common but well documented. COVID toes, the most widely discussed skin manifestation, cause swollen, discolored toes that can look red, purple, or bruised. The same thing can happen to fingers, and sometimes both are affected at once. These changes can appear during the infection or weeks to months afterward.
Beyond COVID toes, dermatologists have identified several other rash patterns linked to the virus:
- Hives
- Itchy bumps
- Blisters resembling chickenpox
- A patchy rash or one with a lace-like pattern
- Round, pinpoint spots on the skin
- Bumps that look like measles on the arms or legs
These rashes are considered rare, but they’re worth knowing about because they can be the only visible sign of infection in some people.
Neurological and Cognitive Symptoms
COVID-19 affects the brain and nervous system more than most respiratory viruses. About 30% of patients in one study reported attention and memory problems during or after their infection. This cognitive impairment, widely called “brain fog,” can make it hard to concentrate, find words, or follow conversations.
Other neurological symptoms reported during acute infection include headaches, dizziness, and confusion. In more severe cases, patients can develop altered mental status or, rarely, more serious complications like stroke. These severe neurological events are uncommon but represent a meaningful difference between COVID-19 and typical seasonal illnesses.
Symptoms in Children
Children generally experience milder COVID-19 symptoms than adults, often resembling a standard cold with a runny nose, mild cough, and low-grade fever. But a small number of children develop a serious inflammatory condition called Multisystem Inflammatory Syndrome in Children (MIS-C), which typically appears two to six weeks after infection.
MIS-C causes persistent fever along with some combination of abdominal pain, vomiting, diarrhea, skin rash, and red eyes. The abdominal pain can be severe enough to mimic appendicitis. In serious cases, children develop low blood pressure, heart problems, or neurological symptoms like severe headache and confusion. Some children also develop swollen, discolored hands or feet, cracked lips, or a swollen tongue with a strawberry-like appearance. MIS-C requires immediate medical attention.
How COVID-19 Differs From the Flu
The symptom lists for COVID-19 and influenza are nearly identical on paper: fever, cough, body aches, sore throat, fatigue. You genuinely cannot tell them apart by symptoms alone. But there are practical differences in how the two illnesses behave.
COVID-19 has a longer incubation period. Flu symptoms typically hit within one to four days of exposure, while COVID-19 takes two to five days on average and can take up to two weeks. COVID-19 also keeps you contagious longer. People with the flu are most infectious in the first three days of illness, while people with COVID-19 remain contagious for about eight days after symptoms start, with peak infectiousness occurring the day before symptoms begin.
The complications also diverge. The flu more commonly leads to secondary bacterial infections like pneumonia caused by bacteria moving into weakened lungs. COVID-19, on the other hand, carries risks of blood clots in the lungs, heart, legs, or brain, and it can trigger MIS-C in children. Perhaps the biggest differentiator is long COVID, which can follow even a mild or asymptomatic infection.
Emergency Warning Signs
Most COVID-19 cases resolve at home, but certain symptoms signal that the body is struggling in ways that need immediate help. These red flags apply to both adults and children:
- Trouble breathing or shortness of breath at rest
- Persistent pain or pressure in the chest
- New confusion or inability to think clearly
- Inability to wake up or stay awake
- Pale, gray, or blue-colored skin, lips, or nail beds
In children, also watch for signs of dehydration like dry mouth, no tears when crying, and decreased urination, or an inability to keep liquids down. Any of these symptoms warrant emergency care, not a wait-and-see approach.
Long COVID Symptoms
Long COVID refers to symptoms that develop within three months of the initial infection and persist for at least two months. It can affect almost any organ system, including the heart, lungs, nervous system, gut, and hormonal system. Over 200 different symptoms have been reported.
The most common long COVID symptoms are fatigue, muscle and joint pain, breathlessness, headaches, difficulty concentrating, and changes in taste. Sleep problems, depression, and anxiety also occur frequently. Some people develop a cluster of symptoms that include dizziness, heart palpitations, and lightheadedness when standing up, related to a condition where the heart rate spikes abnormally with changes in posture. Others experience a pattern where even mild physical or mental effort triggers a crash in energy that can last days.
Beyond persistent symptoms, having had COVID-19 increases the risk of certain new medical conditions, including kidney problems, heart disease, stroke, diabetes, and mental health disorders. These risks exist even for people whose initial infection was mild or produced no symptoms at all.