Gastroenteritis, commonly known as the “stomach flu,” causes millions of Americans to experience sudden bouts of vomiting and diarrhea each year. Despite its nickname, gastroenteritis has nothing to do with influenza; rather, it’s an inflammation of the stomach and intestines that can result from various viruses, bacteria, or parasites. Norovirus is the most common viral cause of gastroenteritis in the United States, responsible for the majority of these sudden and often severe episodes. While most cases resolve on their own within a few days, recognizing the symptoms and knowing when to seek medical care can make a significant difference in managing the illness and preventing complications.

What Is Gastroenteritis?

Gastroenteritis refers to inflammation of the stomach and intestines that can lead to sudden onset of symptoms like nausea, vomiting, diarrhea, and abdominal cramping. The initial cause of inflammation can vary from person to person, but it typically develops as a result of an immune response being triggered. Inflammation tends to disrupt normal digestive function and prevent the intestines from properly absorbing water and nutrients. The resulting fluid loss through vomiting and diarrhea makes dehydration the primary concern in most cases of gastroenteritis.

Most cases of gastroenteritis stem from viral infections, but the main inflammation can come from other infectious agents like bacteria or parasites. Norovirus is the most common viral agent, but rotavirus and adenovirus can also trigger the condition (particularly in young children). Bacterial gastroenteritis occurs less frequently and typically results from consuming contaminated food or water. Common bacterial culprits include Salmonella, E. coli, and Campylobacter. Regardless of the specific infectious agent, the pattern of inflammation and digestive disruption follows a similar course, though the severity and duration of symptoms can vary.1

Norovirus as a Leading Cause

As the single most common cause of acute gastroenteritis in the United States, norovirus is responsible for tens of millions of cases each year. The virus operates by invading cells lining the stomach and small intestine, where it hijacks the cellular machinery to replicate itself rapidly. This invasion triggers a strong immune response as the body attempts to eliminate the infection, resulting in the characteristic inflammation that defines gastroenteritis.

The inflammatory process itself produces most of the uncomfortable symptoms associated with norovirus infection. As immune cells flood the affected tissues, the stomach and intestinal lining become irritated and swollen, triggering waves of nausea and the urge to vomit. The inflammation in the intestines disrupts the normal absorption of water and electrolytes, causing fluid to accumulate in the bowel and resulting in watery diarrhea. The body’s attempt to expel the virus through vomiting and diarrhea, while unpleasant, represents the immune system’s strategy for clearing the infection as quickly as possible.

Norovirus infections typically develop very suddenly, with symptoms appearing 12 to 48 hours after exposure to the virus. Most people experience an abrupt onset of vomiting and diarrhea, often accompanied by stomach cramps, low-grade fever, and general body aches. The intensity of symptoms usually peaks within the first day or two of illness, then gradually subsides as the immune system gains control over the infection.2

How Does Norovirus Spread?

Norovirus is one of the most contagious viruses that affects humans, and the primary transmission method occurs through the fecal-oral route where microscopic particles of the virus from an infected person’s stool or vomit can be ingested by others. This can happen through direct person-to-person contact, such as caring for someone who is ill or shaking hands with an infected individual who hasn’t washed their hands thoroughly. The virus can also contaminate food when sick food handlers touch ready-to-eat items, or it can spread through drinking water that has been exposed to sewage or other sources of contamination.

Surfaces and objects are another significant transmission pathway for norovirus. The virus can survive on countertops, door handles, bathroom fixtures, and other surfaces for days, remaining infectious throughout that time. Anyone who touches a contaminated surface and then touches their mouth can become infected. The virus’s resilience contributes to its ability to cause outbreaks in places like schools, nursing homes, and cruise ships where many people share common spaces and touch the same surfaces.

While anyone can contract norovirus, certain groups face higher risks of severe illness and complications. Young children under five, for instance, can dehydrate rapidly and may struggle to communicate their symptoms effectively. Also, elderly adults over 65 often have less robust immune systems and may already be managing other health conditions that make recovery more difficult. People with weakened immune systems, including those undergoing cancer treatment, transplant patients on immunosuppressants, or individuals with chronic illnesses, can experience more prolonged or severe disease. These vulnerable populations require closer monitoring and may need medical intervention sooner than healthy adults.

Treatment and Management

There is no specific antiviral medication that can cure norovirus infections, which means treatment focuses entirely on supportive care while the immune system clears the virus naturally. Antibiotics are ineffective against norovirus since it’s a viral infection rather than bacterial. The primary goal becomes managing symptoms and preventing complications, particularly dehydration. Most people recover at home within one to three days without requiring medical intervention, though the illness can feel quite severe during its peak. Below are some typical approaches to treatment:

    • Prioritize hydration: The combination of vomiting and diarrhea can cause rapid fluid loss, making it critical to replace lost fluids and electrolytes as quickly as the body can tolerate them. Oral rehydration solutions like Pedialyte or electrolyte packets provide a better balance of salts and minerals than water alone. For adults, diluted juice, broth, or sports drinks can also help, though pediatric electrolyte solutions work best for children. Take small, frequent sips rather than large amounts at once to reduce the likelihood of triggering more vomiting.
    • Rest and allow recovery: During the acute phase when vomiting is most severe, it’s normal to have no appetite, and forcing food can worsen nausea. The body needs time and rest to fight off the infection.
    • Reintroduce food gradually: Once vomiting subsides, start with bland, easy-to-digest foods like crackers, toast, bananas, rice, and applesauce. Avoid fatty, spicy, or dairy-heavy foods for a day or two as they can irritate the recovering digestive system.
    • Use medications cautiously: Over-the-counter medications should only be used after consulting a healthcare provider. Anti-diarrheal medications may sometimes prolong the infection by preventing the body from expelling the virus, while anti-nausea medications might help in severe cases but need professional guidance.

    Contact Cary Gastro for Digestive Health Support

    If you’re experiencing persistent vomiting, diarrhea, or other symptoms of gastroenteritis that aren’t improving, or if you have concerns about dehydration or complications, professional evaluation can provide peace of mind and appropriate care. The experienced gastroenterologists at Cary Gastro specialize in diagnosing and treating all types of digestive disorders, from acute infections like norovirus to chronic gastrointestinal conditions. Our team is here to help you manage your symptoms, recover safely, and maintain optimal digestive health. Contact us today to request an appointment and get the expert care you need.


    1https://pmc.ncbi.nlm.nih.gov/articles/PMC3880795/
    2https://www.cdc.gov/norovirus/data-research/index.html