Menu

Gastroenteritis ("Stomach Flu")

Medically Reviewed by Neha Pathak, MD on September 17, 2021

When you have diarrhea and vomiting, you may say you have the "stomach flu." These symptoms often are due to a condition called gastroenteritis.

With gastroenteritis, your stomach and intestines are irritated and inflamed. The cause is typically a viral or bacterial infection.

Symptoms of Gastroenteritis

With gastroenteritis, the main symptoms you probably have are watery diarrhea and vomiting. You might also have stomach pain, cramping, fever, nausea, and a headache.

Because of diarrhea and vomiting, you also can become dehydrated. Watch for signs of dehydration, such as dry skin and a dry mouth, feeling lightheaded, and being really thirsty. Call your doctor if you have any of these symptoms.

Stomach Flu and Children

Children can get dehydrated quickly, so if your child has the stomach flu, it's important that you look for signs that they are very thirsty or has dry skin or a dry mouth. If you have a baby, look for fewer, drier diapers.

Keep children with gastroenteritis out of day care or school until all symptoms are gone. Check with your doctor before giving your child any medicine. Drugs used to control diarrhea and vomiting aren't usually given to children younger than 5.

To help prevent rotavirus -- the most common cause of stomach flu for children -- there are two vaccines that can be given to infants. Talk to your doctor about the vaccines.

What Causes Gastroenteritis?

There are many ways gastroenteritis can be spread:

  • Contact with someone who has the virus
  • Contaminated food or water
  • Unwashed hands after going to the bathroom or changing a diaper

The most common cause of gastroenteritis is a virus. The main types are rotavirus and norovirus.

Rotavirus is the world's most common cause of diarrhea in infants and young children. Norovirus is the most common cause of serious gastroenteritis and also foodborne disease outbreaks in the U.S.

Although not as common, bacteria such as E. coli and salmonella can also trigger the stomach flu. Salmonella and campylobacter bacteria are the most common bacterial causes of gastroenteritis in the U.S. and are usually spread by undercooked poultry, eggs, or poultry juices. Salmonella can also be spread through pet reptiles or live poultry.

Another bacteria, shigella, is often passed around in day care centers. It typically is spread from person to person, and common sources of infection are contaminated food and drinking water.

Parasites can also cause gastroenteritis, but it's not common. You can pick up organisms such as giardia and cryptosporidium in contaminated swimming pools or by drinking contaminated water.

There are also other unusual ways to get gastroenteritis:

  • Heavy metals (arsenic, cadmium, lead, or mercury) in drinking water
  • Eating a lot of acidic foods, like citrus fruit and tomatoes
  • Toxins that might be found in certain seafood
  • Medications such as antibiotics, antacids, laxatives, and chemotherapy drugs

Gastroenteritis Treatment

Prevent dehydration:

  • Give a child an oral rehydration solution. Call your doctor for age-appropriate dosing specifics.
  • Give an adult as much clear fluid as possible.
  • The person should drink fluids slowly in frequent, small amounts. Drinking too much too fast can make nausea worse.

As symptoms start to ease:

  • Gradually ease food back into the person's diet.
  • Start with bland, easy-to-digest food such as crackers, bananas, toast, rice, and chicken.
  • Avoid dairy, caffeine, and alcohol until recovery is complete.

When to call a doctor

Call 911 if the person is in shock from severe dehydration (faints, can't walk, is confused, or is having trouble breathing)

Seek medical help if:

  • Vomiting in an adult or a child age 2 or older lasts more than 1 day or a fever or severe diarrhea (large amounts of loose stool every 1 to 2 hours) lasts more than 2 days.
  • A child under age 2 has vomiting or diarrhea for more than 12 hours or has a fever with vomiting and diarrhea.
  • Vomit or diarrhea turns bloody or tarry.
  • The person has kidney, liver, or heart disease and must restrict fluid intake.
  • The person develops sudden, severe abdominal pain.
  • There are symptoms of dehydration.
  • Symptoms don’t go away after a week.

Dehydration with these symptoms should be treated in an emergency room:

  • Little to no urination
  • Extreme thirst
  • Lack of tears
  • Dry mouth
  • Sunken eyes
  • Dizziness or lightheadedness
  • Rapid breathing and heartbeat
  • Lack of alertness
  • Blurred or double vision
  • Trouble swallowing or breathing
  • Muscle weakness
WebMD Medical Reference

Sources

SOURCES:

CDC: "Norovirus -- Overview," "Rotavirus -- Prevention," "Rotavirus," "Viral Gastroenteritis."

Cleveland Clinic: "Gastroenteritis."

KidsHealth: "Stomach Flu."

Medscape: "Emergent Treatment of Gastroenteritis."

The Merck Manual Home Health Handbook: "Overview of Gastroenteritis."

National Digestive Diseases Information Clearinghouse: "Viral Gastroenteritis."

PeaceHealth: "Gastroenteritis in Adults and Older Children."

American Academy of Family Physicians: "Treating Gastroenteritis and Dehydration in Your Child."

© 2021 WebMD, LLC. All rights reserved.
Click to view privacy policy and trust info