Viral gastroenteritis is inflammation of the stomach and intestines caused by a virus. The infection can lead to diarrhea and vomiting. It is sometimes called the "stomach flu."

Viral gastroenteritis is a leading cause of severe diarrhea in both adults and children. Many types of viruses can cause gastroenteritis. The most common ones are:

• Rotavirus, the leading cause of severe gastroenteritis in children. It can also infect adults exposed to children with the virus. Outbreaks may also occur in nursing homes.
• Norwalk virus, which is common among school-age children.

These viruses are often found in contaminated food or drinking water. Symptoms of viral gastroenteritis usually appear within 4 to 48 hours after exposure to the contaminated food or water.

Those with the highest risk for severe gastroenteritis include the young, the elderly, and people who have suppressed immune systems.

• Abdominal pain
• Abdominal cramping
• Diarrhea
• Nausea
• Vomiting

Additional symptoms may include: 

• Unintentional weight loss
• Vomiting blood (very rare)
• Excessive sweating
• Clammy skin
• Muscle pain
• Joint stiffness
• Incontinence
• Fever
• Chills
• Poor feeding

Tests that examine stool samples are used to identify the specific virus or rule out a bacterial cause.

The goal of treatment is to prevent dehydration. Fluids and electrolytes (salt and minerals) lost by diarrhea must be replaced. Electrolyte and fluid replacement solutions for children are available in food and drug stores. Juice, soda or water do not replace electrolytes lost from vomiting or diarrhea. Children with diarrhea often benefit from dietary modifications until the diarrhea subsides.

Since the risk of dehydration is greater in infants and young children, parents should closely monitor the number of wet diapers changed per day when the child is sick. People with diarrhea who are unable to take fluids by mouth because of nausea may need intravenous fluids. This is especially true in small children.

Antibiotics do not work for viruses. 

Antidiarrheal medications are generally not given, as they may prolong the infectious process. DO NOT give anti-diarrheal medications to children unless directed to do so by a health care provider.

People taking diuretics who develop diarrhea may be advised by their health care provider to stop taking the diuretic during the acute episode. However, DO NOT stop taking any prescription medicine without first talking to your doctor.

Most infections will go away on their own. Children may become severely ill from dehydration caused by diarrhea.

Rotavirus causes severe gastroenteritis in infants and young children. Severe dehydration and death can occur in this age group.

Call your health care provider if diarrhea persists for more than several days or if dehydration occurs. You should also contact your doctor if the following symptoms are present:

• Blood in the stool
• Low urine output  
• Nausea
• Faintness
• Dizziness
• Dry mouth
• Sunken appearance to the eyes
• Sunken fontanelle (soft spot on an infant's head)
• Confusion

Most infectious organisms are transmitted by unwashed hands. The best way to prevent viral gastroenteritis is to handle food properly and wash hands thoroughly after using the toilet.

RotaTeq is a vaccine used to prevent rotavirus-related gastroenteritis in infants. However, a serious intestinal problem called intussusception has been reported in a small number of infants who received this vaccine. Immediately call your doctor if your child received this vaccine and has stomach pain, vomiting, diarrhea, blood in the stool, or a change in bowel movements.

US Food and Drug Administration. FDA Approves New Vaccine to Prevent Rotavirus Gastroenteritis in Infants, Rockville, MD: National Press Office; February 3, 2006. Press Release P06-16.

Dennehy PH. Acute diarrheal disease in children: epidemiology, prevention, and treatment. Infect Dis Clin North Am. 2005; 19(3): 585-602.

Jabbar A. Gastroenteritis and antibiotic-associated diarrhea. Prim Care. 2003; 30(1): 63-80, vi.