Definition & Facts for Viral Gastroenteritis (“Stomach Flu”)

In this section:

• What is viral gastroenteritis (“stomach flu”)?
• How common is viral gastroenteritis?
• Who is more likely to get viral gastroenteritis?
• What are the complications of viral gastroenteritis?

What is viral gastroenteritis (“stomach flu”)?

Viral gastroenteritis is an infection of your intestines that typically causes watery diarrhea, pain or cramping in your abdomen, nausea or vomiting, and sometimes fever.

Viral gastroenteritis is caused by viruses. Viruses invade normal cells in your body. Many viruses cause infections that can be spread from person to person.

People commonly call viral gastroenteritis “stomach flu,” but the term is not medically correct. Viral gastroenteritis is an infection of the intestines, not the stomach, and it is not caused by influenza (flu) viruses. The flu vaccine does not protect against viral gastroenteritis.

Viral gastroenteritis is acute, meaning it happens suddenly and lasts a short time. Most cases of viral gastroenteritis last less than a week, and most people get better on their own without medical treatment. In some cases, viral gastroenteritis may cause severe symptoms or may lead to dehydration.

How common is viral gastroenteritis?

Viral gastroenteritis is very common. Norovirus is the most common cause of viral gastroenteritis. In the United States, norovirus causes 19 to 21 million cases of viral gastroenteritis each year.¹ Other viruses that cause gastroenteritis are less common.

Who is more likely to get viral gastroenteritis?

Anyone can get viral gastroenteritis. Some people are more likely to have severe symptoms, including

• infants and young children
• older adults
• people with a weakened immune system

What are the complications of viral gastroenteritis?

Dehydration is the most common complication of viral gastroenteritis. When viral gastroenteritis causes you to vomit or have diarrhea, your body loses fluids and electrolytes. If you don’t replace those fluids and electrolytes, you may become dehydrated. When you are dehydrated, your body doesn’t have enough fluids and electrolytes to work properly. See a list of symptoms of dehydration.

Dehydration is especially dangerous in children, older adults, and people with a weakened immune system. Without treatment, dehydration can lead to serious problems such as organ damage, shock, coma, or even death.

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