Diarrhea
Medications
Related eMedTV
Health Channels

Stomach Flu

The stomach flu is not really a flu. Rather, it is a viral infection caused by several different viruses, such as Norwalk virus or rotavirus. Regardless of the virus that causes the infection, symptoms typically include diarrhea and vomiting. Treatment usually consists of managing the symptoms while the body fights off the infection.

What Is the Stomach Flu?

Stomach flu is an intestinal infection caused by several different viruses that can result in diarrhea and vomiting. A highly contagious condition, the stomach flu is the second most common illness in the United States. It causes millions of cases of diarrhea each year.
 
But the so-called "stomach flu" is actually not stomach flu at all. Viruses that cause it affect the small intestine, not the stomach. Furthermore, stomach flu viruses are not flu viruses. The flu virus is the influenza virus, which affects the respiratory system. The influenza virus does not affect the intestines.
 
Regardless of the inaccuracies of the term "stomach flu," it is the most commonly used term to describe what healthcare providers call viral gastroenteritis.
 

Who Does It Affect?

Anyone can get the stomach flu. It occurs in people of all ages and backgrounds.
 
Outbreaks can occur in institutional settings, such as schools, childcare facilities, and nursing homes, and it can occur in other group settings, such as banquet halls, cruise ships, dormitories, and campgrounds.
 

Viruses That Cause It

Many different viruses can cause this illness. Some common types of stomach flu viruses include:
 
  • Rotavirus
  • Adenovirus
  • Caliciviruses
  • Norwalk virus
  • Noroviruses (see Norovirus)
  • Astrovirus.
     
Each virus has its own seasonal activity. For example, in the United States, rotavirus and astrovirus infections occur during the cooler months of the year (October to April), whereas adenovirus infections occur throughout the year.
 
(Click Types of Stomach Flu Viruses for more information.)
 

How Is Stomach Flu Spread?

Stomach flu is highly contagious and can spread easily from person to person. These viruses often can be found in the stool or vomit of infected people. Transmission can occur in one of several ways, including:
 
  • Eating foods or drinking liquids that are contaminated with a stomach flu virus
  • Having direct contact with another person who is infected and showing symptoms (for example, when caring for someone with the illness, or sharing food or eating utensils with someone who is ill)
  • Touching surfaces or objects contaminated with a virus and then putting your hands in your mouth.

 

(Click Stomach Flu Transmission for more information.) 

 

Incubation Period

When a person becomes infected with stomach flu, the virus begins to multiply within the small intestine. After approximately 1 to 2 days (depending on the virus), symptoms can appear. This period between the transmission of the virus and the start of symptoms is the "stomach flu incubation period." In some cases, the incubation period can be as short as 4 hours.
 
(Click Stomach Flu Incubation Period for more information.)
 

Contagious Period

Whether or not a person is contagious during the incubation period will depend on which virus he or she is infected with. For example, with a rotavirus infection, the person is contagious during the incubation period. He or she is also contagious while experiencing symptoms. Once the diarrhea has ended, a person with rotavirus gastroenteritis is no longer contagious.
 
With a norovirus infection (including Norwalk virus), a person is not usually contagious during the stomach flu incubation period. People infected with norovirus gastroenteritis are usually contagious from the moment they begin feeling ill to at least 3 days after recovery. Some people may be contagious for as long as 2 weeks after recovery.
 

Symptoms of Stomach Flu

Not all people who are infected with a stomach flu virus will develop associated symptoms. If symptoms do occur, the illness can begin suddenly. Symptoms of stomach flu can last anywhere from 1 to 10 days, depending on which virus a person is infected with. Symptoms can be mild to severe. The most common symptoms are diarrhea and vomiting.
 
(Click Stomach Flu Symptoms for more information.)
 

Making a Diagnosis

In order to make a diagnosis, the healthcare provider will ask a number of questions about a person's medical history and will perform a physical exam, looking for signs and symptoms of stomach flu. If the doctor suspects rotavirus, he or she may test the stool for it. Besides rotavirus, there are no specific routine lab tests commonly used to identify other stomach flu viruses.
 
(Click Stomach Flu Diagnosis to learn more about how it is diagnosed.)
 

Treatment for Stomach Flu

Stomach flu has no specific treatment; antibiotics are not effective against viruses. Treatment focuses on reducing the symptoms and preventing dehydration while the body fights the infection.
 
People with stomach flu should rest, drink clear liquids, and eat easy-to-digest foods. For infants and young children, oral rehydration solutions can replace lost fluids, minerals, and salts.
 
(Click Stomach Flu Treatment for a more in-depth look at these treatment options.)
 

Prevention

No vaccine is available for stomach flu, with the exception of a newly released rotavirus vaccine called RotaTeq®. This oral vaccine for infants aged 6 weeks to 32 weeks was approved in February 2006 by the US Food and Drug Administration (FDA).
 
Therefore, the best prevention method involves reducing your chances of coming in contact with stomach flu viruses.
 
(Click Stomach Flu Prevention for more information.)
 

Other Names for Stomach Flu

Besides stomach flu, people use a variety of other names to describe a viral infection of the intestines that leads to diarrhea and vomiting. Some of these other names include:
 
Written by/reviewed by: Arthur Schoenstadt, MD
Last reviewed by: Arthur Schoenstadt, MD
Other Articles in This eMedTV Presentation