Virtual Care > Virtual Care: Stomach Flu (Viral Gastroenteritis)

What is Stomach Flu (Viral Gastroenteritis)?

Viral gastroenteritis is an inflammation, swelling, and irritation of the inside lining of your gastrointestinal tract. A virus causes this illness. It can infect your stomach, small intestine, and large intestine.

Viral gastroenteritis is very common. In most cases, it lasts only a few days and doesn’t require treatment. The biggest danger is dehydration from loss of fluid due to diarrhea and vomiting.

What causes viral gastroenteritis?

Several viruses can cause gastroenteritis. Viruses can be found in the vomit and the diarrhea of infected people. It can live for a long time outside the body. People who are infected can spread the virus to objects they touch, especially if they don’t wash their hands after using the bathroom. Food workers with the infection can spread it to others through food and beverages. Sewage that gets into the water supply can also spread the illness. Although viral gastroenteritis is sometimes called "stomach flu," the seasonal influenza (flu) virus does not cause it.

Some of the common viruses that cause gastroenteritis include:

  • Rotavirus. This virus most commonly infects infants age 3 to 15 months. The illness lasts for 3 to 7 days and is most common in fall and winter.
  • Norovirus. This is the most common cause of adult infections and the virus that’s usually responsible for outbreaks on cruise ships. Symptoms last from 1 to 3 days and can occur any time of the year.
  • Adenovirus. This virus occurs year-round and affects children under age 2. Symptoms last from 5 to 12 days.

Many other viruses can also cause viral gastroenteritis.

What are the symptoms of viral gastroenteritis?

Symptoms of viral gastroenteritis usually begin about 1 to 2 days after the virus gets into the body.

Common symptoms include:

  • Nausea
  • Vomiting
  • Watery diarrhea

 Other possible symptoms are:

  • Headache
  • Fever
  • Chills
  • Stomachache

Signs of dehydration:

  • Decreased urine output
  • Dark-colored urine
  • Dry skin
  • Thirst
  • Dizziness

Signs of dehydration in young children:

  • Dry diapers (from a lack of urination)
  • Lack of tears
  • Dry mouth
  • Drowsiness
  • Sunken fontanel (the soft spot on the top of an infant’s head)

How is viral gastroenteritis diagnosed?

Your health care provider will most likely diagnose your condition based on your history and symptoms. You will rarely need testing. If your symptoms persist, your health care provider may ask for a stool sample to look for viruses, bacteria, and parasites.

Can viral gastroenteritis be prevented?

Vaccines are available to protect children from rotavirus. Health care providers give shots to babies before age 6 months. You and your children can help prevent viral gastroenteritis by taking these steps:

  • Wash hands for 20 seconds with soap and water after going to the bathroom, after changing a diaper, and before touching any food.
  • If someone in the house has gastroenteritis, wash all surfaces that might be contaminated with a bleach-based cleaner.
  • Avoid any food or water with warnings of contamination.

How is viral gastroenteritis treated?

Specific treatment is not usually needed. Usually, you simply need to drink plenty of fluids and rest at home until the virus leaves your system. In rare cases, you may need treatment for severe dehydration, with IV (intravenous) fluids.

Helpful home care tips include:

  • Drink plenty of light fluids like water, ice chips, fruit juice, broth, and sports drinks.
  • Avoid drinks that contain milk, caffeine, and alcohol.
  • Once you feel hungry again, start with mild, easy to digest foods.
  • Rehydrate children with oral rehydration solutions (such as Pedialyte).

When should I call my health care provider?

Viral gastroenteritis is common in children and adults. In most cases, the disease is not serious and will run its course in a few days. Call your health care provider if you or a family member has vomiting or diarrhea that’s not getting better, or if you have any signs of dehydration.

Key points

  • Viral gastroenteritis is an inflammation of the inside lining of your gastrointestinal tract.
  • It can be caused by rotavirus, norovirus, and adenovirus.
  • Babies can be vaccinated against rotavirus.
  • Symptoms of viral gastroenteritis are nausea, vomiting, and watery diarrhea.
  • Dehydration is the most serious complication of this illness.
  • This illness should run its course in a few days but may need medical attention of diarrhea or vomiting persists or if there are signs of dehydration.

Visit with a Virtual Care health care provider on the phone or online for help with your symptoms.

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