Covid-19, caused by the SARS-CoV-2 virus, has a wide range of symptoms that can vary greatly from person to person. Two of the most common early symptoms are fever and cough. However, some people, especially children, may experience digestive issues like diarrhea as an initial symptom before developing the more well-known respiratory symptoms. In this article, we’ll look at the evidence around whether diarrhea can be an early sign of Covid-19.
Can Covid-19 start with diarrhea?
Several studies have found that a portion of Covid-19 patients experience diarrhea or other digestive issues at the onset of illness:
- A study published in The American Journal of Gastroenterology looked at 204 Covid-19 patients in China and found that 99 (48.5%) had digestive symptoms as their chief complaint. Of those 99 patients, 83 (83.8%) developed fever later on.
- Research from the Journal of Microbiology, Immunology and Infection on 73 hospitalized Covid-19 patients in China found that 11 (15%) experienced diarrhea as the first symptom of disease.
- A study in JAMA Network Open analyzed data from over 1,000 Chinese Covid-19 patients. They found that digestive issues occurred in 12.4% of patients as the first symptom.
Based on these studies, it appears that while diarrhea at the start of illness is fairly uncommon, it can be an initial symptom of Covid-19 in some cases before respiratory symptoms develop. Experts estimate that about 2-10% of Covid-19 patients experience diarrhea or nausea/vomiting before fever and cough.
Other early symptoms
While diarrhea, fever, and cough are common initial symptoms, Covid-19 can begin with a variety of other symptoms as well:
- Fatigue
- Body aches or muscle pain
- Sore throat
- Headache
- Loss of taste or smell
- Congestion or runny nose
Some people may only experience mild cold-like symptoms at first that gradually worsen over several days. The wide range of potential early symptoms makes Covid-19 challenging to diagnose based on symptoms alone. Testing is needed to confirm infection.
How common is diarrhea with Covid-19?
Throughout the full course of illness, diarrhea appears to be common with Covid-19, reported in 5-50% of patients depending on the study.
A meta-analysis in PLoS One aggregated data from over 4,000 Covid-19 patients and found:
- 7.7% had diarrhea
- 7.8% had nausea/vomiting
Another meta-analysis in Gastroenterology analyzed data from over 6,000 Covid-19 patients and found:
- 17.6% experienced diarrhea
- 12.4% experienced nausea/vomiting
So while diarrhea is not as prevalent as respiratory symptoms like cough and shortness of breath, it is still reasonably common throughout the course of Covid-19 illness.
Why does Covid-19 cause diarrhea in some patients?
Researchers are still studying why exactly SARS-CoV-2 can trigger digestive issues like diarrhea. Here are some potential reasons:
- The virus may directly infect and damage cells in the gastrointestinal tract, leading to inflammation and abnormal gut function.
- Some patients experience changes in gut microbes from antibiotic use or other factors that allow overgrowth of diarrhea-causing bacteria.
- In severe Covid-19 cases, widespread inflammation and reduced blood flow to the gut likely contribute to diarrhea.
- Medications used in treatment like antivirals may disrupt normal digestion and lead to diarrhea as a side effect.
How long does Covid-19 diarrhea last?
Diarrhea associated with Covid-19 often lasts only 1-3 days, though it may persist longer in severe illnesses. One study found diarrhea lasted an average of 3.3 days in patients with mild to moderate Covid-19 who experienced this symptom.
Most cases of Covid-19 diarrhea are mild and self-limiting, not requiring any specific treatment. However, staying hydrated is important, and over-the-counter anti-diarrheal medication can provide relief if needed. Severe or persisting diarrhea may require medical attention, especially in vulnerable groups like older adults.
Can diarrhea be the only symptom of Covid-19?
It’s possible but uncommon for diarrhea to occur as the sole symptom of Covid-19. One study found that among Covid-19 patients who experienced diarrhea, it was the only symptom in about 6% of cases.
Much more often, diarrhea occurs alongside other typical symptoms like fever, cough, and muscle aches. Having diarrhea in isolation without any other symptoms is not very likely with Covid-19. But it’s still possible, highlighting the importance of testing if diarrhea is persisting.
Is diarrhea more common with Covid-19 variants?
Some emerging data suggests that new SARS-CoV-2 variants may cause diarrhea or other digestive issues more often compared to earlier forms of the virus.
For example, researchers found that during the period when the Alpha variant was predominant in the UK, prevalence of diarrhea among Covid-19 patients increased compared to earlier phases of the pandemic. The Delta variant has also been associated with increased frequency of diarrhea in some studies.
More research is still needed, but it appears that Covid-19 variants could alter the typical symptoms like provoking diarrhea more readily in those infected. Close monitoring of symptoms is important even with vaccinations to watch for signs of new variants.
Is Covid-19 diarrhea contagious?
Yes, the diarrhea associated with Covid-19 is contagious just like respiratory secretions from an infected person.
The SARS-CoV-2 virus can be shed in stool even before symptoms start and for days to weeks after initial infection. Viral particles in diarrhea and vomit can cause infection if they enter the mouth, nose, or eyes of another person nearby.
Proper handwashing is critical to avoid transmitting Covid-19 through contaminated surfaces if you develop diarrhea. Anyone with Covid-19 diarrhea should isolate from others as much as possible.
Covid-19 vs. other diarrheal illnesses
Besides Covid-19, many digestive infections can cause diarrhea including:
- Viral gastroenteritis (stomach flu)
- Bacterial infections like salmonella and C. difficile
- Parasitic infections
- Food poisoning
- Medication side effects
- Chronic bowel diseases like IBS
Isolating Covid-19 as the cause can be difficult since many of these conditions have overlapping symptoms. Testing is key to confirm Covid-19, especially if you have known exposures or risk factors.
Seeking prompt treatment is also wise if diarrhea is severe, bloody, or accompanied by concerning symptoms like dehydration, fever, and abdominal pain that could indicate a serious infection.
Key takeaways
Here are some top takeaways on whether Covid-19 can start with diarrhea:
- About 2-10% of Covid-19 patients experience diarrhea or nausea before respiratory symptoms emerge.
- Throughout illness, around 5-50% of patients develop diarrhea, more common in severe cases.
- New variants may provoke diarrhea more readily than original forms of the virus.
- Covid-19 diarrhea often lasts 1-3 days and is typically mild, but dehydration is a concern.
- Covid-19 diarrhea is contagious. Careful hygiene and isolation are essential.
- Testing is required to differentiate Covid-19 diarrhea from other potential causes.
When to seek emergency care
Most cases of Covid-19 diarrhea are mild and can be managed with home treatment. However, you should seek prompt medical attention if you experience:
- Blood or pus in stool
- Severe abdominal pain
- Fever over 103 F
- Signs of dehydration like dizziness, rapid heart rate, or dark urine
- Diarrhea persisting longer than 2 weeks
Severe dehydration, bowel perforation, or secondary infections can occur in some cases and may require hospitalization for IV fluids, pain control, or antibiotic treatment. Seek emergency care immediately if diarrhea is accompanied by these alarming symptoms.
Conclusion
Diarrhea affects a meaningful portion of patients with Covid-19, both at the start of illness and throughout infection. While most cases are mild, Covid-19 diarrhea can signal a need for testing and isolation to avoid transmission. Pay attention to any digestive issues that are unusual or persisting and seek medical advice, especially if additional red flags are present or you are at high-risk of complications. With vigilant monitoring of all symptoms, cases of Covid-19 diarrhea can typically be managed safely at home.
