Gastrointestinal (GI) issues, commonly described as a stomach upset, can indeed be a symptom of COVID-19 infection. While the illness caused by the SARS-CoV-2 virus is primarily known for its respiratory symptoms like cough and fever, it is a systemic disease that affects multiple organ systems throughout the body. The virus’s ability to infect cells outside the lungs means that the digestive tract is also a site of viral activity. Understanding this systemic reach is important for proper recognition, especially since these symptoms can sometimes appear before any respiratory issues.
Gastrointestinal Symptoms in COVID-19 Patients
The umbrella term “stomach upset” in the context of COVID-19 typically encompasses several specific gastrointestinal complaints. The most frequently reported GI symptoms include diarrhea, nausea, vomiting, and abdominal pain. Diarrhea is often one of the most common manifestations, sometimes affecting up to a third of patients in various studies. Nausea and a loss of appetite, known as anorexia, are also highly prevalent.
The overall prevalence of experiencing at least one GI symptom during a COVID-19 infection is substantial, with some cohorts reporting that over 60% of patients experienced one. These digestive issues are generally mild to moderate in severity and usually resolve relatively quickly. Their timing can vary considerably; for some individuals, GI issues may precede the onset of classic respiratory symptoms. In a smaller subset of patients, these gastrointestinal complaints may be the only symptoms present throughout the entire course of the illness.
How the Virus Affects the Digestive System
The reason the SARS-CoV-2 virus can cause digestive distress is rooted in its biological mechanism of cellular entry. The virus relies on a specific protein receptor on human cells called Angiotensin-Converting Enzyme 2 (ACE2) to gain access. While ACE2 is abundant in the lungs, it is also highly expressed on the surface of enterocytes, the absorptive cells that line the small intestine. This high concentration provides a direct pathway for the virus to infect and damage the intestinal lining cells.
The binding of the virus to the ACE2 receptors on these enterocytes can lead to cell destruction and subsequent inflammation within the gut. This local inflammation and damage to the intestinal barrier are thought to be the main drivers of symptoms such as diarrhea and abdominal discomfort. The virus can be detected in the stool of infected individuals, known as fecal shedding of viral RNA. This viral presence confirms the active infection of the digestive system, and this shedding can persist even after respiratory symptoms have resolved.
When GI Symptoms Are the Primary or Only Sign
When GI symptoms like new-onset diarrhea or nausea appear without a corresponding fever or cough, it is important to consider COVID-19 as a possible cause. Data suggests that in approximately 15% to 20% of cases, individuals may present solely with gastrointestinal issues. Because these symptoms are indistinguishable from those caused by common stomach viruses or food poisoning, testing is the only definitive way to determine if the underlying cause is SARS-CoV-2. A positive test result, even with only GI symptoms, is critical for informing isolation protocols to prevent further spread.
For managing these COVID-related GI issues at home, the focus should be on supportive care to prevent complications. Diarrhea and vomiting can rapidly lead to dehydration and electrolyte imbalance, making consistent fluid intake a priority. Oral rehydration solutions, which contain the necessary balance of water, sugars, and salts, are highly recommended over plain water alone. A bland diet consisting of easily digestible foods, such as rice, bananas, and toast, can help rest the digestive system and reduce irritation.
While most cases of COVID-related GI upset are self-limiting and improve within a few days, certain signs warrant immediate medical attention. These red flags include signs of severe dehydration, such as excessive thirst, reduced urination, or dizziness when standing up. Persistent or severe abdominal pain, bloody stools, or vomiting that prevents all fluid intake are also serious symptoms that require prompt evaluation by a healthcare provider. Consulting a physician is particularly important for patients with underlying medical conditions, as they may be at a higher risk for complications.