Viral 

Gastroenteritis 

National Digestive Diseases Information Clearinghouse 

U.S. Department 

of Health and 

Human Services 

NATIONAL 

INSTITUTES 

OF HEALTH 

What is viral gastroenteritis? 

Viral gastroenteritis is inflammation of the 

lining of the stomach, small intestine, and 

large intestine. Several different viruses can 

cause viral gastroenteritis, which is highly 

contagious and extremely common. Viral 

gastroenteritis causes millions of cases of 

diarrhea each year. 

Anyone can get viral gastroenteritis and most 

people recover without any complications, 

unless they become dehydrated. 

Large 

intestine 

Small 

intestine 

Stomach 

Viral gastroenteritis is inflammation of the lining of 

the stomach, small intestine, and large intestine. 

What are the symptoms of 

viral gastroenteritis? 

The main symptoms of viral gastroenteritis 

are 

• watery diarrhea 

• vomiting 

Other symptoms include 

• headache 

• fever 

• chills 

• abdominal pain 

Symptoms usually appear within 12 to 

48 hours after exposure to a gastroenteritiscausing virus and last for 1 to 3 days. Some 

viruses cause symptoms that last longer. 

What are the complications 

of viral gastroenteritis? 

Dehydration is the most common complication of viral gastroenteritis. When someone 

does not drink enough fluids to replace those 

that are lost through vomiting and diarrhea, 

dehydration can result. When dehydrated, 

the body does not have enough fluids to 

keep the proper balance of important salts 

or minerals, known as electrolytes. Infants, 

young children, older adults, and people with 

weak immune systems have the greatest risk 

of becoming dehydrated. 
 

The signs of dehydration in adults are 

•	� excessive thirst 

•	� infrequent urination 

•	� dark-colored urine 

•	� dry skin 

•	� lethargy, dizziness, or faintness 

Signs of dehydration in babies and young 

children are 

•	� dry mouth and tongue 

•	� lack of tears when crying 

•	� no wet diapers for 3 hours or more 

•	� high fever 

•	� unusually cranky or drowsy behavior 

•	�sunken eyes, cheeks, or soft spot in the 

skull 

Also, when people are dehydrated, their skin 

does not flatten back to normal right away 

after being gently pinched and released. 

People should talk with a health care 

provider if they have 

•	� blood in their stool, which may indicate 

a bacterial infection 

•	�symptoms that are severe or last more 

than a few days 

•	�symptoms of dehydration 

Severe dehydration may require intravenous fluids and hospitalization. Untreated 

severe dehydration can cause serious health 

problems such as organ damage, shock, or 

coma—a sleeplike state in which a person is 

not conscious. 

What causes viral 

gastroenteritis? 

Four types of viruses cause most cases of 

viral gastroenteritis. 

Rotavirus 

Rotavirus is the leading cause of gastroenteritis among infants and young children. 

Rotavirus infections are most common in 

infants 3 to 15 months old. Symptoms usually appear 1 to 3 days after exposure. Rotavirus typically causes vomiting and watery 

diarrhea for 3 to 7 days, along with fever and 

abdominal pain. Rotavirus can also infect 

adults who are in close contact with infected 

children, but the symptoms in adults are 

milder. 

Caliciviruses 

Caliciviruses cause infection in people of 

all ages. Norovirus is the most common 

calicivirus and the most common cause of 

viral gastroenteritis in adults. Norovirus is 

usually responsible for epidemics of viral 

gastroenteritis. Norovirus outbreaks occur 

all year but are more frequent from October 

to April. People infected with norovirus typically experience nausea, vomiting, diarrhea, 

abdominal cramps, fatigue, headache, and 

muscle aches. The symptoms usually appear 

1 to 2 days after exposure to the virus and 

last for 1 to 3 days. 

2	� Viral Gastroenteritis 
 

Adenovirus 

Adenovirus mainly infects children younger 

than 2 years old. Of the 49 types of adenoviruses, one strain affects the gastrointestinal tract, causing vomiting and diarrhea. 

Symptoms typically appear 8 to 10 days after 

exposure and last 5 to 12 days. Adenovirus 

infections occur year-round. 

Astrovirus 

Astrovirus primarily infects infants and 

young children, but adults may also be 

infected. This virus causes vomiting and 

watery diarrhea. Symptoms usually appear 

3 to 4 days after exposure and last 2 to 

7 days. The symptoms are milder than the 

symptoms of norovirus or rotavirus infections. Infections occur year-round, but the 

virus is most active during the winter months. 

Viral gastroenteritis is often mistakenly 

called “stomach flu,” but it is not caused 

by the influenza virus. Some forms of 

gastroenteritis are caused by bacteria 

or parasites rather than viruses. For 

information about bacterial infections, 

see the Bacteria and Foodborne Illness 

fact sheet from the National Institute 

of Diabetes and Digestive and Kidney 

Diseases (NIDDK). 

How is viral gastroenteritis 

transmitted? 

Viral gastroenteritis is transmitted from 

person to person. Viruses are present in the 

stool and vomit of people who are infected. 

Infected people may contaminate surfaces, 

objects, food, and drinks with viruses, especially if they do not wash their hands thoroughly after using the bathroom. When an 

infected person with unwashed hands shakes 

hands with or touches another person, the 

virus can spread. When an infected person 

vomits, the virus can become airborne. 

People may be infected with viruses by 

•	� touching contaminated surfaces or 

objects and then touching their mouths 

•	�sharing food, drink, or eating utensils 

with infected people 

•	� eating foods that are contaminated with 

the virus, such as oysters from contaminated waters 

•	�swallowing airborne particles that contain viruses 

Norovirus is especially contagious. Norovirus can survive for months on surfaces that 

are not thoroughly disinfected with a bleach 

solution. Hard surfaces should be cleaned 

with a mixture of 2 cups of bleach and 

1 gallon of water. 

3	� Viral Gastroenteritis 
 

Infected people who do not have symptoms 

can still transmit viruses. Viruses may be 

present in the stool up to 2 weeks after a 

person recovers from gastroenteritis. 

Outbreaks of viral gastroenteritis can occur 

in households, childcare settings, schools, 

nursing homes, cruise ships, camps, dormitories, restaurants, and other places where 

people gather in groups. People who suspect 

they were exposed to a virus in one of these 

settings may want to contact a local health 

department that tracks viral gastroenteritis 

outbreaks. 

How is viral gastroenteritis 

diagnosed? 

Viral gastroenteritis is usually diagnosed 

based on symptoms alone. People who have 

symptoms that are severe or last for more 

than a few days may want to see a health 

care provider for additional tests. A health 

care provider may ask for a stool sample 

to test for rotavirus or norovirus or to rule 

out bacteria or parasites as the cause of the 

gastroenteritis. 

During an epidemic of viral gastroenteritis, 

health care providers or public health officials may test stool samples to find out which 

virus is responsible for the outbreak. 

How is viral gastroenteritis 

treated? 

Most cases of viral gastroenteritis resolve 

over time without specific treatment. Antibiotics are not effective against viral infections. 

The primary goal of treatment is to reduce 

symptoms and prevent complications. 

Over-the-counter medicines such as loperamide (Imodium) and bismuth subsalicylate 

(Pepto-Bismol) can help relieve symptoms 

in adults. These medicines are not recommended for children. 

Eating, Diet, and Nutrition 

The following steps may help relieve the 

symptoms of viral gastroenteritis in adults: 

•	� drinking plenty of liquids such as fruit 

juices, sports drinks, caffeine-free soft 

drinks, and broths to replace fluids and 

electrolytes 

•	�sipping small amounts of clear liquids or 

sucking on ice chips if vomiting is still a 

problem 

•	� gradually reintroducing food, starting 

with bland, easy-to-digest foods such 

as rice, potatoes, toast or bread, cereal, 

lean meat, applesauce, and bananas 

•	� avoiding fatty foods, sugary foods, dairy 

products, caffeine, and alcohol until 

recovery is complete 

•	� getting plenty of rest 

4	� Viral Gastroenteritis 
 

Children present special concerns. Because 

of their smaller body size, infants and children are likely to become dehydrated more 

quickly from diarrhea and vomiting. The 

following steps may help relieve symptoms of 

viral gastroenteritis and prevent dehydration 

in children: 

•	� giving oral rehydration solutions such 

as Pedialyte, Naturalyte, Infalyte, and 

CeraLyte 

•	� giving food as soon as the child is 

hungry
�

•	� giving infants breast milk or full 

strength formula, as usual, along with 

oral rehydration solutions 

Older adults and adults with weak immune 

systems should also drink oral rehydration 

solutions to prevent dehydration. 

How can viral gastroenteritis 

be prevented? 

People can reduce their chances of getting or 

spreading viral gastroenteritis if they 

•	� wash their hands thoroughly with soap 

and warm water for 20 seconds after 

using the bathroom or changing diapers 

and before eating or handling food 

•	� disinfect contaminated surfaces such as 

countertops and baby changing tables 

with a mixture of 2 cups of household 

bleach and 1 gallon of water 

•	� avoid foods and drinks that might be 

contaminated 

The U.S. Food and Drug Administration has 

approved two vaccines to protect children 

from rotavirus infections: rotavirus vaccine, 

live, oral, pentavalent (RotaTeq); and rotavirus vaccine, live, oral (Rotarix). RotaTeq is 

given to infants in three doses at 2, 4, and 

6 months of age. Rotarix is given in two 

doses. The first dose is given when the infant 

is 6 weeks old, and the second is given at 

least 4 weeks later but before the infant is 

24 weeks old. 

Parents of infants should discuss rotavirus 

vaccination with a health care provider. 

For more information, parents can visit the 

Centers for Disease Control and Prevention 

rotavirus vaccination webpage at www.cdc. 

gov/vaccines/vpd-vac/rotavirus. 

In the past, rotavirus infections were most 

common from November to April in the 

United States. However, recently widespread vaccination slowed the transmission 

of the virus, delaying rotavirus activity until 

late February. Overall rates of infection have 

also been lower than in previous years. 

5	� Viral Gastroenteritis 
 

Points to Remember 

•	� Viral gastroenteritis is inflammation 

of the lining of the stomach, small 

intestine, and large intestine. Several 

different viruses can cause viral gastroenteritis, which is highly contagious and 

extremely common. 

•	� The main symptoms of viral gastroenteritis are watery diarrhea and vomiting. 

•	� Dehydration is the most common complication of viral gastroenteritis. 

•	� When someone does not drink enough 

fluids to replace those that are lost 

through vomiting and diarrhea, dehydration can result. Signs of dehydration 

in adults are excessive thirst, infrequent 

urination, dark-colored urine, dry skin, 

and lethargy, dizziness, or faintness. 

•	�Infants, young children, older adults, 

and people with weak immune systems 

have the greatest risk of becoming 

dehydrated. 

•	� Viral gastroenteritis is transmitted from 

person to person. 

•	� Diagnosis of viral gastroenteritis is usually based on symptoms alone. 

•	� Most cases of viral gastroenteritis 

resolve over time without specific 

treatment. Antibiotics are not effective against viral infections. The primary goal of treatment is to reduce 

symptoms. 

•	� Adults with viral gastroenteritis should 

drink plenty of liquids such as fruit 

juices, sports drinks, caffeine-free soft 

drinks, and broths to replace fluids and 

electrolytes. 

•	� Children with viral gastroenteritis 

should be given oral rehydration solutions to prevent dehydration. 

•	� People can reduce their chances of getting or spreading viral gastroenteritis if 

they wash their hands thoroughly with 

soap and warm water for 20 seconds 

after using the bathroom or changing 

diapers and before eating or handling 

food, disinfect contaminated surfaces, 

and avoid foods or liquids that might be 

contaminated. 

Hope through Research 

The NIDDK’s Division of Digestive Diseases 

and Nutrition supports basic and clinical 

research into gastrointestinal diseases, 

including viral gastroenteritis. 

Researchers are investigating 

•	� diagnostic tests for virus strains 

•	� new vaccines for rotavirus and norovirus 

•	� the use of probiotics to treat 

gastroenteritis 

Participants in clinical trials can play a more 

active role in their own health care, gain 

access to new research treatments before 

they are widely available, and help others by 

contributing to medical research. For information about current studies, visit 

www.ClinicalTrials.gov. 

6	� Viral Gastroenteritis 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

For More Information 

Centers for Disease Control and Prevention 

1600 Clifton Road 

Atlanta, GA 30333 

Phone: 1–800–CDC–INFO 

(1–800–232–4636) 

Fax: 404–371–5488 

Email: cdcinfo@cdc.gov 

Internet: www.cdc.gov 

Acknowledgments 

Publications produced by the Clearinghouse 

are carefully reviewed by both NIDDK scientists and outside experts. This publication 

was originally reviewed by Mary K. Estes, 

Ph.D., and Robert Atmar, M.D., Baylor College of Medicine. 

You may also find additional information about this 

topic by visiting MedlinePlus at www.medlineplus.gov. 

This publication may contain information about 

medications. When prepared, this publication 

included the most current information available. 

For updates or for questions about any medications, 

contact the U.S. Food and Drug Administration tollfree at 1–888–INFO–FDA (1–888–463–6332) or visit 

www.fda.gov. Consult your health care provider for 

more information. 

The U.S. Government does not endorse or favor any 

specific commercial product or company. Trade, 

proprietary, or company names appearing in this 

document are used only because they are considered 

necessary in the context of the information provided. 

If a product is not mentioned, the omission does not 

mean or imply that the product is unsatisfactory. 

7 Viral Gastroenteritis 
 

 

 

 

 

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This publication is available at 

www.digestive.niddk.nih.gov. 

U.S. DEPARTMENT OF HEALTH 

AND HUMAN SERVICES 

National Institutes of Health 

NIH Publication No. 11–5103 

April 2011 

The NIDDK prints on recycled paper with bio-based ink.