COVID-19 can present with a wide range of symptoms, including gastrointestinal (GI) issues like nausea, vomiting, and diarrhea. These are also common signs of the stomach flu, also called viral gastroenteritis. Because of the overlap, it may be difficult to distinguish between the two illnesses without testing.

The most reliable way to confirm a COVID-19 infection is through a diagnostic test. However, assessing whether you also have respiratory or systemic symptoms may help you make an informed guess in the meantime.

COVID-19 vs. Stomach Flu Symptoms

Although gastroenteritis is often referred to as the "stomach flu," it is not related to the influenza virus. COVID-19 is caused by the SARS-CoV-2 virus, which affects the respiratory tract but can also impact the digestive system.

While both conditions can cause GI symptoms, COVID-19 often includes respiratory and systemic signs. Here's a symptom comparison:

symptom comparison chart:

Symptoms Stomach Flu COVID-19
Abdominal pain Yes No
Body or muscle aches No Yes
Cough No Yes
Diarrhea Yes Sometimes
Difficulty breathing No Yes
Fatigue No Yes
Fever or chills Sometimes Yes
Headache No Yes
Loss of smell or taste No Yes
Nausea Yes Sometimes
Runny nose/congestion No Yes
Sore throat No Yes
Vomiting Yes Sometimes

Risk Factors for GI Symptoms

Certain lifestyle and health factors may increase your risk of developing gastrointestinal symptoms, whether related to COVID-19 or not.

common risk factors include:

  • High alcohol or cannabis use

  • Excessive caffeine intake

  • Low fiber diet

  • High consumption of sugary and starchy foods

  • Poor sleep quality

  • Sedentary lifestyle

  • Psychological stress, including anxiety, depression, or trauma

  • Inflammation following a prior infection

How Long Do GI Symptoms Last With COVID-19?

Gastrointestinal symptoms linked to COVID-19 may vary in timing and duration. Diarrhea typically begins one to eight days after infection onset and lasts between two and six days.

Some individuals continue to experience GI issues as part of long COVID. These persistent symptoms, which can last beyond 12 weeks after the initial illness, may include diarrhea, abdominal discomfort, nausea, and vomiting.

When To Consult a Healthcare Provider

In most cases, stomach flu does not require professional medical care and improves with rest and hydration. However, if you experience any symptoms associated with COVID-19, you should get tested and isolate while waiting for results.

seek immediate medical attention if you experience:

  • Chest pain

  • Difficulty breathing

  • Bluish or discolored lips, nails, or skin

  • Trouble staying awake or waking up

  • New confusion or mental disorientation

  • Severe vomiting or inability to keep fluids down

  • Signs of dehydration such as fast heart rate, dry mouth, or rapid breathing

Individuals with weakened immune systems, chronic health conditions, or those who are pregnant should be especially cautious and seek prompt medical advice if symptoms appear.

A Quick Review

Both COVID-19 and the stomach flu can cause nausea, vomiting, and diarrhea. However, COVID-19 often includes respiratory symptoms such as coughing, fatigue, sore throat, or loss of taste and smell, while stomach flu tends to remain focused on GI symptoms.

If your symptoms include fever, chest pain, or severe fatigue—or if you're at risk of complications—consult a healthcare provider and get tested for COVID-19 to confirm the cause and guide appropriate care.