Influenza, commonly known as the flu, is a respiratory illness caused by influenza viruses. These viruses primarily target the nose, throat, and lungs, leading to a range of respiratory symptoms. While primarily a respiratory illness, some individuals can also experience digestive upset as part of their illness. Symptoms can include nausea, vomiting, or diarrhea.
How Flu Affects the Digestive System
The influenza virus can lead to digestive symptoms through several biological mechanisms, even though it primarily replicates in the respiratory tract. The body’s widespread inflammatory response to the infection is a factor. When the immune system fights the virus, it releases signaling molecules called cytokines, which can affect various parts of the body, including the digestive system, potentially causing nausea and diarrhea.
Research in animal models suggests that influenza infection in the lungs can indirectly impact the gut. This can involve changes in the gut microbiome, the community of microorganisms living in the intestines. Studies indicate that influenza infection can lead to an increase in certain immune cells in the intestine, which can contribute to intestinal injury and inflammation.
While the influenza virus itself does not directly infect the cells lining the digestive tract, the systemic effects of the infection can manifest as digestive distress. This means that digestive symptoms are often secondary to the body’s overall response to the viral infection rather than a direct attack on the gut by the virus. The autonomic nervous system, which regulates digestion, can also be affected by the virus, contributing to these symptoms.
Flu Versus “Stomach Flu”
It is important to distinguish between influenza and what is commonly called “stomach flu,” as they are caused by different viruses and primarily affect different body systems. Influenza, or the flu, is a respiratory infection caused by influenza viruses that primarily impacts the nose, throat, and lungs. Common flu symptoms include fever, cough, sore throat, muscle aches, and fatigue.
In contrast, “stomach flu” is a lay term for viral gastroenteritis, an infection of the stomach and intestines. This condition is caused by viruses, and its primary symptoms are digestive, such such as diarrhea, nausea, vomiting, and abdominal cramps. While both illnesses can cause fever and fatigue, the defining symptoms differ significantly between the two.
While some individuals with influenza may experience digestive symptoms, these are less common and milder compared to the severe digestive distress seen with viral gastroenteritis. The flu vaccine provides protection against influenza viruses but does not protect against the viruses that cause “stomach flu.”
Relief for Digestive Symptoms
Managing mild digestive symptoms associated with the flu focuses on supportive care to ease discomfort and prevent complications like dehydration. Staying well-hydrated is important. Sip clear liquids like water or broths. Avoiding sugary drinks and caffeine can help prevent further stomach upset.
Eating bland foods, such as toast, crackers, bananas, rice, or applesauce, can be easier on the digestive system when experiencing nausea or vomiting. Avoid foods that are greasy, spicy, or high in fiber until symptoms improve. Getting adequate rest allows the body to conserve energy and focus on recovery.
While most mild digestive symptoms from the flu can be managed at home, seek medical attention if symptoms worsen or become severe. Signs that warrant medical consultation include persistent vomiting, severe dehydration, high or prolonged fever, or if symptoms do not improve after several days.