What Is Stomach Flu?

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Viral gastroenteritis is the second most common illness in the United States. Dubbed the "stomach flu," it is not caused by the influenza virus and it is not a respiratory illness. Rather, the stomach flu is usually caused by a virus (usually norovirus or rotavirus) that attacks the intestinal tract and causes swelling and discomfort.

how long stomach flu symptoms last
Verywell / Cindy Chung

Stomach Flu Symptoms

If you have ever had the stomach flu, you are probably well aware of the most common symptoms. Vomiting and diarrhea tend to be its calling cards, but there are other symptoms that can go along with this illness as well.

With stomach flu, you are also likely to experience:

  • Fever
  • Nausea
  • Abdominal pain
  • Fatigue/tiredness

Symptom onset and duration can depend on the specific viral infection. For example, with norovirus, the typical incubation period (the time between exposure and the start of symptoms) for stomach flu is about 12 to 48 hours. The symptoms typically last one to three days, though diarrhea may linger up to 10 days in some people.

Complications

Dehydration from fluid loss is the most common complication from the stomach flu. It can lead lead to additional symptoms and concerns such as lowered blood pressure. Seek medical attention right away if you see any signs of severe dehydration, but keep in mind dehydration can look different in people of different ages as well.

For example, in adults, common signs include infrequent urination, excessive thirst, and very dark urine. In babies and young children, common signs include no tears when crying, no wet diapers for more than three hours, and excessive irritability

Both children and adults who are dehydrated may have "skin-tenting" where the skin does not flatten back out immediately if you pinch it.

Causes

The stomach flu is highly contagious and spread through close contact with infected people, touching contaminated surfaces, or eating food contaminated with a virus.

The most common cause of viral gastroenteritis among adults in the United States is norovirus. In children under the age of 2 years, rotavirus and adenovirus are common and can spread quickly in daycare centers.

Diagnosis

Most episodes of stomach flu do not require medical treatment and will go away on their own within a couple of days. Diagnosis is based on symptoms and similar cases in the community.

If symptoms are severe or do not resolve in a few days, your doctor may order testing, such as stool culture, blood work, or imaging tests to rule out other causes.

Treatment

In most cases, the stomach flu can typically be self-treated with fluids, diet, and over-the-counter medication.

To treat the stomach flu at home:

  • Do not eat or drink anything for about 15 minutes after vomiting to let your stomach rest.
  • Take small sips of water or an electrolyte drink, such as Pedialyte or Gatorade, every five to 10 minutes to keep hydrated without irritating the stomach. Avoid drinking fruit juices and sodas.
  • Once small sips are tolerated for about an hour, slowly increase the amount you are drinking.
  • After taking nothing but fluids for several hours, try eating bland foods such as crackers, toast, rice, and broth.
  • To treat the fever, Tylenol (acetaminophen) is typically more gentle on the stomach than Advil (ibuprofen) and aspirin.
  • Anti-diarrhea medications are not recommended during the first 24 hours, as diarrhea is the body's way of expelling the virus.

Infants, children, older adults, and people with weakened immune systems, who are at greater risk of dehydration from a stomach bug, may require medical attention. Prescription medications can reduce vomiting, and people who are severely dehydrated may need IV fluids.

When to Seek Emergency Care

If you or your child experience any of the following, seek medical attention right away:

  • Vomiting blood
  • Large amounts of blood or mucus in the stool
  • Confusion
  • Feeling lightheaded or fainting when standing
  • Severe abdominal pain
  • Unusual sleepiness/difficulty waking (child)
  • Fever greater than 101 degrees
  • Dehydration
  • Persistent vomiting lasting two days or longer

Prevention

Preventing the stomach flu is difficult because it is highly contagious. If you or someone in your life has the stomach flu, try to keep your distance. Of course, that's sometimes impractical.

Do the best you can and follow good handwashing practices. In particular, be sure to wash your hands after touching something that many others have touched (like a public doorknob) and after changing a child's diaper. You should also avoid sharing drinks and eating utensils with someone who is sick.

Hand sanitizer may not be as effective at killing norovirus, so favor washing your hands well with soap and water.

Wash linens in hot water and don't share items between sick and well family members. Look out for "unintentional sharing" too, such as placing your toothbrush in the same holder as theirs.

A Word From Verywell

Whether you call it stomach flu, a stomach bug, gastroenteritis, food poisoning, or something else, the fact is it's not pretty. The symptoms it causes are unpleasant, to say the least. Although it can be hard to avoid if someone in your home has it, knowing what to do and steps you can take to protect yourself should help.

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Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Merck Manual Professional Version. Gastroenteritis. Updated June 2019.

  2. Popkin BM, D'Anci KE, Rosenberg IH. Water, hydration, and healthNutr Rev. 2010;68(8):439–458. doi:10.1111/j.1753-4887.2010.00304.x

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