Stomach Flu

Viral gastroenteritis is an inflammation, swelling and irritation of the inside lining of your gastrointestinal tract. It is caused by a virus and can infect the stomach, small intestine, and large intestine.

Viral gastroenteritis is very common. In most cases, it lasts only a few days and does not require treatment. The greatest risk is dehydration due to fluid loss caused by diarrhea and vomiting.

What causes viral gastroenteritis?

Several viruses can cause gastroenteritis. Viruses are found in the vomit and diarrhea of infected people. They can live outside the body for a long time. Infected people can transmit the virus to objects they touch, especially if they do not wash their hands after going to the toilet. 

Employees of grocery stores with the infection can transmit it to others through food and drink. Sewage that enters the water supply can also spread the disease. Although viral gastroenteritis is sometimes referred to as "stomach flu," the seasonal flu virus does not cause it.

Some of the common viruses that cause gastroenteritis include:

  • Rotavirus. This virus most commonly infects infants aged three to 15 months. The illness lasts for three to seven 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 two. Symptoms last from five 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 one to two days after the virus enters the body.

Common symptoms include:

  • Nausea

  • Vomiting

  • Watery diarrhea

Other possible symptoms include:

  • 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 licensed health care provider will most likely diagnose your condition based on your history and symptoms. Tests are rarely needed. If your symptoms persist, your licensed doctor may request a stool sample to look for viruses, bacteria and parasites.

Can viral gastroenteritis be prevented?

Vaccines are available to protect children from rotavirus. Licensed health care providers give shots to babies before age 6 months. You and your children can help prevent viral gastroenteritis by taking the following measures:

  • Wash your hands with soap and water for 20 seconds after going to the toilet, changing nappies and touching food

  • If someone in the house has gastroenteritis, wash all surfaces that could be contaminated with bleach

  • Avoid 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 tips for home care are:

  • Drink plenty of light fluids such as 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 licensed 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 licensed 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 include nausea, vomiting and watery diarrhea

  • Dehydration is the most serious complication

  • This disease should take its course in a few days, but may require medical attention if diarrhea or vomiting persists or there are signs of dehydration

Visit with a Virtual Care health care provider online for help with your symptoms.