Viral gastroenteritis

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at June 24, 2016
StartDiseasesViral gastroenteritis

Gastroenteritis is a digestive condition that is also known as stomach flu despite having no connection to the influenza virus or flu. Viral gastroenteritis is cause by a number of viruses that lead to the symptoms associated with this illness. The most dangerous of these is norovirus.


Definition & Facts

Viral gastroenteritis is a common condition that is easy for most healthy individuals to manage. During a bout of the illness, the stomach and intestines become inflamed, which leads to stomach pain and digestive discomfort.

The elderly are the most at-risk population for death by viral gastroenteritis. According to the Centers for Disease Control, cases that led to death more than doubled between 1999 and 2007. Adults 65 and over accounted for more than 80% of those deaths. However, the majority of cases do not result in life-threatening illness.

Symptoms & Complaints

Viruses that lead to gastroenteritis incubate for between one and three days, which means people will notice symptoms about that length of time after infection. Symptoms will appear with varying degrees of severity and will last for anywhere from a day to more than a week. 

The symptoms of viral gastroenteritis occur in the digestive system. The illness may present with only one or two mild symptoms or can develop serious symptoms though the latter is rare. Symptoms include:

If symptoms persist or worsen, it can mean the illness cannot be managed at home. People who have been vomiting for several days, see blood in their vomit or blood in stool, have a temperature above 104-degrees Fahrenheit (38.9-degrees Celsius), are dehydrated or appear jaundiced (have yellow skin and eyes) have a more severe case of viral gastroenteritis. They need to be seen by a doctor to prevent further complications. 


There are four virus types that cause most incidences of viral gastroenteritis. They are norovirus, rotavirus, astrovirus, and adenovirus. Kids are more likely to get sick from rotavirus, while adults develop immunity with age. Prior to the widespread use of rotavirus vaccines, rotavirus had infected most children in America by the time they turned five years old.

Norovirus is more likely to affect adults. There are about 50 types of adenovirus, causing everything from the common cold to severe gastroenteritis. Astrovirus was discovered about 50 years ago. Gastroenteritis caused by astrovirus typically lasts four days at most and rarely causes hospitalization.

Viral gastroenteritis spreads several ways. Infants and children are often infected when they put their hands in their mouths. Outbreaks are caused by contaminated food or drink shared by groups of people. Viruses can also spread person to person via vomit particles and fecal matter. Infected individuals failing to wash their hands are a leading cause of both viral and bacterial gastroenteritis

Young children, seniors and people with weakened immune systems are more likely to develop viral gastroenteritis. They are also more likely to develop complications from the disease. Risk also goes up in winter, when people congregate in close quarters. 

Diagnosis & Tests

Viral gastroenteritis presents the same way as multiple other illnesses, including gastroenteritis caused by bacteria like Clostridium difficile infection (C. diff). Because treatment involves managing symptoms, doctors do not need to know the cause to treat the disease. Therefore, in-depth tests are rarely conducted. However, tests may be required for certain cases.

Doctors may order stool samples if a patient has been traveling in developing countries. Another cause for stool samples is if the patient has blood in the stool or the doctor suspects the patient has parasites

Dehydration can be determined by looking at symptoms. Dry mouth and oliguria or decreased urine output are symptoms of dehydration. Doctors can also apply pressure to the skin, causing it to lose color. If it takes longer than usual for the color to return to the skin, it is called slowed capillary refill, which can indicate dehydration. 

If a patient reports symptoms such as stomach pain, vomiting, diarrhea and nausea, gastroenteritis is suspected. Questions about symptoms are typically enough to reach a diagnosis. However, doctors may want to exclude other possibilities, such as kidney infection, diabetes and inflammatory bowel syndrome. Therefore, blood tests and urine samples remain part of the standard testing for patients with viral gastroenteritis, even though doctors are not testing for a virus through those tests.

Treatment & Therapy

The majority of viral gastroenteritis cases are manageable at home without prescription medication. The virus itself will run its course on its own. Symptoms will subside over usually two to four days without any medical intervention. The only time treatment is required is for complicated cases or at-risk patients, such as the elderly and individuals with HIV.

People can manage viral gastroenteritis at home by rehydrating themselves. Water or rehydration drinks sold at the pharmacy are recommended for recovery. Yogurt and probiotics can be a helpful part of a recovery diet. A healthy, normal diet free of sugary foods is recommended for patients of all age groups. Trying to eat foods that are rich in nutrients is key to feeling better. Full function and appetite will return on its own.

Over-the-counter medications can help with symptoms like fever and muscle aches, if vomiting is not present. There are liquid preparations as well for those who cannot hold down solid food. For cases that require medicine or hospitalization, there are several options. Doctors may offer antiemetic medicines, which can reduce nausea and vomiting. They can also order IV fluids, which helps individuals who cannot hold down water. 

Prevention & Prophylaxis

There is currently a rotavirus vaccine being used all over the world. Before the availability of the rotavirus vaccine, 50,000 to 70,000 children were hospitalized each year in the United States due to infection.

Lifestyle and hygiene choices are still the first line of defense against viral gastroenteritis. Breastfeeding can help increase immunity in children, especially in developing countries. Everyone who prepares food at home or in a professional setting should thoroughly wash their hands with soap and water after using the restroom, whether they have symptoms or not.