In this Special Feature, we round up the existing evidence on the gastrointestinal symptoms of COVID-19.
All data and statistics are based on publicly available data at the time of publication. Some information may be out of date. Visit our coronavirus hub for the most recent information on COVID-19.
For much of the pandemic, the primary reported symptoms of COVID-19 have been a persistent cough and fever. But as case loads have risen and new variants have emerged, new symptoms have surfaced.
According to one review from September 2020, 53% of people hospitalized with COVID-19 experienced at least one gastrointestinal (GI) symptom during their illness.
As the pandemic continues and scientists learn more about the disease, COVID-19’s impact on the gut is becoming more clear. There is some evidence that having GI symptoms of COVID-19 — or developing the disease in addition to an underlying GI condition — may increase the risk of COVID-19 severity and complications.
In this Special Feature, we look at what researchers know so far about the prevalence, causes, and effects of COVID-19’s GI symptoms.
Respiratory symptoms, such as coughing or trouble breathing, are common symptoms of COVID-19.
- esophagus, the tube that connects the mouth to the stomach
- small and large intestines
The first person with confirmed COVID-19 in the United States experienced 2 days of nausea and vomiting before developing diarrhea. And one of the earliest American studies found that around 32% of patients with the disease reported GI symptoms, most commonly diarrhea, nausea, or a loss of appetite.
The research is ever-evolving. According to a February 2021
- lack of appetite (19.9%)
- distortion or lack of taste (15.4%)
- diarrhea (13.2%)
- nausea (10.3%)
- vomiting up blood or GI bleeding (9.1%)
An earlier review, published in January 2021, found much broader rates of symptom prevalence, such as:
- diarrhea (9–34%)
- nausea, vomiting, or both (7–16%)
- abdominal pain (3–11%)
Less commonly, COVID-19 may also be associated with:
It seems that
Early studies suggest that GI symptoms
“[GI] symptoms are common, with up to one-third of patients with COVID-19 presenting first with GI symptoms. Nausea and vomiting may be present in up to two-thirds of patients with COVID-19. Approximately 40% of patients with COVID-19 will have loss of appetite, and up to 50% will have diarrhea. Abdominal pain is less common, occurring in less than 10%.”
The virus enters intestinal cells after its characteristic spike proteins bind to ACE-2. Once inside the cell, the virus uses the cells’ own machinery to produce copies of viral proteins and RNA. Like many viruses, SARS-CoV-2 carries its genetic information on a strand of RNA, much like human DNA.
When SARS-CoV-2 particles leave an infected cell, it triggers the release of cytokines, small proteins that play a role in inflammation. This process may cause GI symptoms.
Symptoms such as pain, nausea, and diarrhea may also occur if viruses damage GI tissues.
And research suggests that the composition of the gut microbiota, the community of microbes that inhabit the intestines or stomach, can influence COVID-19.
Once inside the GI tract, the virus can also
Meanwhile, nausea and diarrhea are common side effects of medications, such as antivirals, that healthcare professionals use to manage COVID-19.
Also, there is increasing evidence that SARS-CoV-2 could pass to others via fecal-oral transmission. This means that a person could acquire the infection by accidentally consuming or inhaling droplets of infected feces.
In fact, fecal samples from the first person with confirmed COVID-19 in the U.S. contained particles of SARS-CoV-2.
And research shows that people may shed viral particles in their feces after the virus is undetectable in the upper respiratory system, such as the lungs, nose, and throat.
This may change our understanding of how the virus can transmit to others and for how long.
People with GI symptoms of COVID-19 may be more likely to develop complications or be more at risk from those complications.
A study from November 2020 found that having GI symptoms was associated with a heightened risk of developing acute respiratory distress syndrome, as have subsequent studies.
The research also found that experiencing GI symptoms increased the likelihood of needing noninvasive mechanical ventilation and tracheal intubation, procedures that carry risks.
And a report from October 2020 found that children with COVID-19 who develop GI symptoms were more likely to experience severe, critical infections and cardiac impairments.
Another study, from December 2020, concluded that the presence of GI symptoms in adults was associated with more severe illness and fatal outcomes. A
Studies have also suggested that people with preexisting GI conditions might experience more serious disease and negative complications.
Some researchers speculate that this connection may exist because GI diseases can cause intestinal metaplasia, which involves the stomach lining being replaced with cells similar to intestinal lining cells.
Many GI conditions may also make it easier to develop GI infections because they damage or weaken the intestinal or stomach lining. Some of these conditions, such as inflammatory bowel disease,
Medications used to treat GI diseases or symptoms can also
There has been less speculation about why having GI symptoms of COVID-19 seems to increase the risk of severe disease and poor outcomes in the absence of underlying health conditions.
People with viral infection in their respiratory and GI tracts
There are also around 100 times more ACE-2 receptors in the GI tract than respiratory organs, so it may be able to house more viruses when it acquires an infection.
People with symptoms affecting multiple organs also
Early evidence seems generally consistent. But broader studies are needed to determine the true relationship between GI symptoms, GI conditions, and COVID-19.
For example, some research indicates that people who develop GI symptoms of COVID-19 may actually experience milder disease.
Knowing how often, when, and why COVID-19 causes GI symptoms could have significant benefits.
If these symptoms are as common as research suggests, SARS-CoV-2 testing services could widen their reach to include people with appetite loss, vomiting, and diarrhea, with or without respiratory symptoms. This could help identify COVID-19 cases earlier.
Tracking GI symptoms in a population may also help identify disease outbreaks before they become apparent.
A study comparing rates of internet searches for these symptoms commonly associated with COVID-19 in 15 states found that, in some states, surges in searches occurred 3–4 weeks before surges in case levels.
A similar study, published in January 2022, monitored global internet trends, and it concluded that internet search data could reliably predict “COVID-19 outbreaks at both global and regional levels.”
Researchers also need to know whether having a preexisting GI disease increases the risk of severe COVID-19, complications, and death. And they will have to figure out whether GI conditions make people more prone to developing COVID-19.
This could help healthcare professionals know how to handle potential, active, or resolved cases of COVID-19 in people with GI diseases better.
It will also be important to confirm whether COVID-19 can spread through feces, and if so, how long this is possible.
In a review from early February 2021, feces samples from
If the disease can spread through feces, this could change current hygiene and self-isolation recommendations.
The Centers for Disease Control and Prevention (CDC) recommend that people self-isolate for
If feces containing the new coronavirus can spread the infection, it will also be important to monitor and potentially treat wastewater to reduce transmission. The
Meanwhile, researchers also need to learn more about the long-term effects of COVID-19 on the GI tract.
Some preliminary studies show that certain symptoms may persist for weeks or months after the person has recovered from the initial illness. A recent review found that approximately 16% of people may still experience nausea and vomiting after recovering, while 12% may continue to experience digestive disorders.
It will take time to fully understand when and why COVID-19 triggers GI symptoms and how they affect disease severity and outcomes. For now, as a meta-analysis published in February 2022 concluded, it seems that GI symptoms and abdominal pain are associated with more severe disease.
It will likely take even longer to figure out whether and how often symptoms persist.
But as daunting as it sounds, this knowledge could bring about improvements in how we diagnose, treat, monitor, and track COVID-19.
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