Symptoms of COVID-19

The symptoms of COVID-19 are variable depending on the type of variant contracted, ranging from mild symptoms to a potentially fatal illness. Common symptoms include coughing, fever, loss of smell and taste, with less common ones including headaches, nasal congestion and runny nose, muscle pain, sore throat, diarrhea, eye irritation, and toes swelling or turning purple, and in moderate to severe cases, breathing difficulties. People with the COVID-19 infection may have different symptoms, and their symptoms may change over time. Three common clusters of symptoms have been identified: a respiratory symptom cluster with cough, sputum, shortness of breath, and fever; a musculoskeletal symptom cluster with muscle and joint pain, headache, and fatigue; and a cluster of digestive symptoms with abdominal pain, vomiting, and diarrhea. In people without prior ear, nose, or throat disorders, loss of taste combined with loss of smell is associated with COVID-19 and is reported in as many as 88% of symptomatic cases. Of those who show symptoms, 81% develop only mild to moderate symptoms (up to mild pneumonia), while 14% develop severe symptoms (dyspnea, hypoxia, or more than 50% lung involvement on imaging) that require hospitalization, and 5% of patients develop critical symptoms (respiratory failure, septic shock, or multiorgan dysfunction) requiring ICU admission. As of 2024–2025, the majority of infections are characterized as mild or asymptomatic; however, risk remains stratified by age and underlying health conditions, with severe outcomes—including respiratory failure and multi-organ dysfunction—occurring in a significantly smaller percentage of the general vaccinated population than in early 2020.

At least a third of the people who are infected with the virus do not develop noticeable symptoms at any point in time. These asymptomatic carriers tend not to get tested and can still spread the disease. Other infected people will develop symptoms later (called "pre-symptomatic") or have very mild symptoms and can also spread the virus. As is common with infections, there is a delay, or incubation period, between the moment a person first becomes infected and the appearance of the first symptoms. The median delay for COVID-19 is four to five days possibly being infectious on 1–4 of those days. Most symptomatic people experience symptoms within two to seven days after exposure, and almost all will experience at least one symptom within 12 days. Most people recover from the acute phase of the disease. However, some people continue to experience a range of effects, such as fatigue, for prolonged periods after an initial COVID-19 infection. This is the result of a condition called long COVID, which can be described as a range of persistent symptoms that continue for months or years. Long-term damage to organs has been observed after the onset of COVID-19. Multi-year studies are underway to further investigate the protracted effects of long COVID. Reducing the risk of long COVID includes staying up to date on the most recent COVID-19 vaccine, practicing good hygiene, maintaining clean indoor air, and physical distancing from people infected with a respiratory virus. The Omicron variant became dominant in the U.S. in December 2021. Symptoms with the Omicron variant are less severe than they are with other variants.

Overview

Some less common symptoms of COVID-19 can be relatively non-specific; however the most common symptoms are fever, dry cough, and loss of taste and smell. Among those who develop symptoms, approximately one in five may become more seriously ill and have difficulty in breathing. Emergency symptoms include difficulty in breathing, persistent chest pain or pressure, sudden confusion, loss of mobility and speech, and bluish face or lips; immediate medical attention is advised if these symptoms are present. Further development of the disease can lead to complications including pneumonia, acute respiratory distress syndrome, sepsis, septic shock, and kidney failure. Some symptoms usually appear sooner than others, with deterioration usually developing in the second week. In August 2020, scientists at the University of Southern California reported the "likely" order of initial symptoms of the COVID-19 disease as a fever followed by a cough, then sore throat, muscle pain, or headache, followed by nausea, vomiting, and diarrhea. This contrasts with the most common path for influenza where it is common to develop a cough first and fever later. Impaired immunity in part drive disease progression after SARS-CoV-2 infection. While health agency guidelines tend to recommend isolating for 14 days while watching for symptoms to develop, there is limited evidence that symptoms may develop for some patients more than 14 days after initial exposure.

Symptom profile of variants

The frequency of symptoms predominating for people with different variants may differ from what was observed in the earlier phases of the pandemic.

Delta Infection with the Delta variant causes flu-like symptoms. Common symptoms include fever, coughing, headache, shortness of breath, muscle pain, and weakness. Most people also experience numbness or loss of one's senses of smell and taste. In severe cases, symptoms include difficulty breathing, low oxygen levels in blood, acute respiratory distress syndrome, septic shock, increased blood acidity, coagulation dysfunction, and failure of multiple organs.

Omicron

British epidemiologist Tim Spector said in mid-December 2021 that the majority of symptoms of the Omicron variant were the same as a common cold, including headaches, sore throat, runny nose, fatigue and sneezing, so that people with cold symptoms should take a test. "Things like fever, cough and loss of smell are now in the minority of symptoms we are seeing. Most people don't have classic symptoms." People with cold symptoms in London (where Covid was spreading rapidly) are "far more likely" to have Covid than a cold. A unique reported symptom of the Omicron variant is night sweats, particularly with the BA.5 subvariant. Also, loss of taste and smell seem to be uncommon compared to other strains.

Systemic Typical systemic symptoms include fatigue, and muscle and joint pains. Some people have a sore throat.Hoarseness and a dry or irritated throat have also been reported as symptoms, especially for patients infected with the XFG strain.

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