Viral gastroenteritis, also known as stomach flu, is a condition that affects the stomach and intestines. Symptoms can be mild or severe and include stomach cramps, diarrhea, and vomiting. It is an infectious condition and can occur as a cluster of outbreaks in close communities, such as hospital wards. Different viruses can cause viral gastroenteritis, and they can present with similar symptoms.

Viral gastroenteritis is the most common cause of diarrhea in the world, according to a 2021 study. Norovirus is the most common virus responsible for viral gastroenteritis. It can be resistant to both freezing and hot conditions and alcohol- or chorine-based disinfectant.

Good hygiene is essential to control the spread of the condition.

This article will explain the symptoms of viral gastroenteritis in adults and children and how long they may last. It will also explain when a person should contact a doctor and what treatment may be effective.

a person is feeding a child who is sick with viral gastroenteritisShare on Pinterest
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Signs and symptoms of viral gastroenteritis may include an upset stomach in adults as well as children.

Symptoms in adults

Symptoms of viral gastroenteritis include:

Occasionally, a person with viral gastroenteritis may experience fever, which may include chills and aches.

A common complication of viral gastroenteritis is dehydration. Symptoms can include:

A person may also experience decreased skin turgor. This means that if a person pinches and releases their skin, it does not immediately return to how it usually looks.

Symptoms in young children

Symptoms of viral gastroenteritis in infants and children are similar to those in adults, and include:

  • diarrhea
  • vomiting
  • abdominal pain
  • fever

But dehydration may be more serious and have more quickly appearing complications in infants than adults.

Dehydration in infants and children

Caregivers should monitor infants and children carefully for signs of dehydration, which can cause serious complications.

Signs of dehydration a caregiver may notice include:

  • urinating less frequently, for example, having no wet diapers for 3 hours or more
  • dry mouth
  • crying with no tears
  • sunken cheeks or eyes
  • decreased skin turgor
  • a lack of energy

A caregiver who suspects that an infant is severely dehydrated should seek immediate medical help.

Learn how to tell if a toddler is dehydrated here.

Viral gastroenteritis can last between 1 and 3 days for otherwise healthy adults.

The disease can cause symptoms for longer in children, older adults, or those with compromised immune systems.

Learn more about how long viral gastroenteritis can last here.

A person who has viral gastroenteritis should know when to contact a doctor to avoid possible complications of the condition.

If a person develops any of the following symptoms, they should consult their healthcare professional immediately:

  • feeling irritable or lacking in energy
  • temperature above 103.1°F (39.5°C)
  • diarrhea lasting longer than 48 hours
  • regular vomiting alongside diarrhea
  • sharp pains in the stomach or bottom
  • black, tarry stools that may contain blood
  • dehydration symptoms
  • inability to drink enough liquid or oral hydration solutions

Adults who have compromised immune systems (for example due to cancer treatment), pregnant people, and older adults should contact their healthcare professional immediately upon experiencing symptoms of viral gastroenteritis.

When to contact a doctor for infants and children

Infants and children are particularly susceptible to complications from viral gastroenteritis. A caregiver should talk with a healthcare professional for advice if they are concerned.

Seek help if the child has any of the following symptoms or signs:

  • drowsiness, irritability, lack of energy
  • diarrhea lasting longer than 24 hours
  • pain
  • black, tarry stools or signs of blood or pus
  • frequent loose, watery stools
  • frequent vomiting
  • unable to keep liquid in the body long enough to rehydrate
  • signs of dehydration
  • fever

Different viruses can be responsible for viral gastroenteritis, and they can cause similar symptoms. These include:

  • Norovirus: Symptoms of norovirus often begin 12–48 hours after exposure to the virus. They may last for 1–3 days.
  • Rotavirus: Symptoms of rotavirus often begin 2 days after exposure to the virus. They may last for 3–8 days.
  • Adenovirus: Symptoms of adenovirus often begin 3–10 days after exposure to the virus. They may last for 1–2 weeks.
  • Astrovirus: Symptoms of astrovirus often begin 4–5 days after exposure to the virus. They may last 1–4 days.

Treatment will be similar among different viruses that have caused viral gastroenteritis.

A healthcare professional will diagnose viral gastroenteritis by analyzing a person’s symptoms. They may also ask for a medical history and perform a physical examination.

A stool test may be useful to distinguish the virus responsible for the illness.

A person with viral gastroenteritis will usually get better with rest and plenty of fluids. Replacing fluids is the most important goal of treatment.

Healthcare professionals advise drinking water and oral hydration solutions to help replace electrolytes. Sipping small amounts of clear liquids can help to retain liquid if a person is still vomiting.

Liquids that can help to replace fluid include water, broth, and fruit juice. Saltine crackers can help electrolyte replacement.

Medical treatment

Some over-the-counter (OTC) medications may help a person with viral gastroenteritis relieve their symptoms. For example, loperamide (Imodium) and bismuth subsalicylate (Pepto Bismol or Kaopectate) can help relieve symptoms of diarrhea.

People who have a fever or who are noticing blood in their stools should not take OTC medicines. These people should consult a healthcare professional for advice on how to treat their condition, which may include medication to control vomiting or the use of probiotics.

Treatment for infants and children

OTC medications may not be safe for children to take. Caregivers should discuss medical treatment with a doctor.

Children should continue to drink breast milk or formula if it is part of their usual routine.

Ask a healthcare professional for advice before giving a child oral rehydration solution. A 2016 study found that dilute apple juice could be substituted for oral hydration solution with few ill effects for children between 6 months and 5 years of age with mild gastroenteritis.

A person with viral gastroenteritis should eat when they feel they are able. They should keep drinking plenty of liquids to maintain hydration. A person with viral gastroenteritis may lose their appetite for a short while, or they may vomit after eating.

small portionshigh fat foods
fresh fruithigh sugar foods
cooked vegetableshigh fiber foods
lean meatspicy foods
breaddairy, if the stomach is not tolerating lactose
rice and pasta

When a person’s appetite returns, they should resume their usual diet. They may wish to reintroduce heavier foods more slowly.

Learn 33 foods to eat if a person has the stomach flu here.

To help prevent viral gastroenteritis, a person can:

  • wash their hands well, especially:
    • after using the bathroom
    • after changing a child’s diaper
    • before and after handling, preparing, or eating food
  • disinfect surfaces, especially if they have had contact with infected stools or vomit
  • wash clothes or fabrics, especially if they have come into contact with a person’s infected vomit or stools
  • avoid handling or preparing food for other people if they have symptoms of viral gastroenteritis
  • keep children and adolescents at home if they have symptoms of viral gastroenteritis
  • protect children by vaccinating them against rotavirus, which is a common cause of viral gastroenteritis

Viral gastroenteritis can occur due to a number of viruses, but the main symptoms include vomiting, diarrhea, and stomach cramps. The condition is highly infectious, so a person should maintain good hygiene to avoid infecting other people.

It is important to keep drinking clear liquids to avoid dehydration.

Consult a healthcare professional if the person is an infant, toddler, or older adult, or has a compromised immune system. Carefully monitor possible signs of dehydration, which is a potentially serious complication of viral gastroenteritis.

An otherwise healthy person should recover fully with rest, plenty of drinks, and light meals.