Stomach flu is a viral infection of your intestines. The medical term for stomach flu is viral gastroenteritis.

Common symptoms include:

  • loose, watery diarrhea
  • abdominal cramping
  • nausea
  • vomiting

Despite its name, the stomach flu isn’t caused by the same virus that causes influenza. However, there are several other viruses that can cause the stomach flu.

The stomach flu is contagious, which means it can be spread from one person to another.

Learn how long the stomach flu is contagious, how it spreads, and how you can avoid getting it.

Typically, it takes a few days after exposure for symptoms to appear. However, this can depend on the specific virus.

According to a 2013 study, symptoms of norovirus, rotavirus, and sapovirus usually show up 1 to 2 days after exposure, while it can take 4 to 5 days for people to develop symptoms of astrovirus. Symptoms of adenovirus mostly show up 5 to 6 days after exposure, but they can take anywhere from 2 to 14 days to appear.

Symptoms of the stomach flu typically last 1 to 3 days. Infections in those with higher risk may last longer.

Generally speaking, the virus is most likely to spread from the time your symptoms first appear until several days after your symptoms have gone away. Some viruses, such as rotavirus, can be transmitted before symptoms begin.

Even after your symptoms have cleared up, the virus may also still shed in your stool for several weeks. For example, norovirus can be shed in stool for 2 weeks or longer and rotavirus can be found in stool for up to 10 days.

Because the infection may still be transmitted to others even after you’ve completely recovered, practicing good hand hygiene is vital.

There are several types of viruses that can cause stomach flu. They include:

  • Noroviruses. Noroviruses are the most common cause of stomach flu worldwide, accounting for around 50 percent of cases and over 90 percent of outbreaks. They’re very contagious and are mostly transmitted via the fecal-oral route. People typically contract the infection by consuming contaminated food or water. You can also get it through indirect contact, such as touching a surface after a person with norovirus touched it. Restaurants and other food service settings are responsible for more norovirus outbreaks than any other type of setting.
  • Rotaviruses. The infection rotavirus is more common in children than in adults. Rotaviruses can live on surfaces and the virus can also be transmitted through indirect contact or airborne transmission. Most people with rotavirus contract it after handling the stool of someone with the infection. While rotavirus still affects many children, cases and outbreaks have seen a steep decline since a vaccine was introduced in 2006.
  • Adenoviruses. Like rotavirus, adenovirus infections primarily affect young children. However, this infection is less common. Adenoviruses are airborne. You can also get the infection through personal contact (such as shaking hands) or by touching a contaminated surface.
  • Astroviruses. Astroviruses also mainly affect children. They’re transmitted via the fecal-oral route. Drinking contaminated water can result in an astrovirus infection.
  • Sapoviruses. Sapoviruses belong to the same virus family as noroviruses. They’re most common in children under 5 years old. Consuming contaminated food or water or coming into contact with the stool or vomit of someone with sapovirus can cause an infection.

While anyone can get stomach flu, some people are at a higher risk of developing severe illness, including:

The risk of a stomach flu outbreak increases when large groups of people are in close contact with each other. Examples of this include:

  • cruise ships
  • restaurants, buffets, or banquets
  • care facilities such as daycare centers and nursing homes
  • college campuses
  • military bases

The viruses that cause stomach flu are present in stool and vomit. These viruses can contaminate food, water, and surfaces — especially if a person doesn’t practice proper hand hygiene after using the restroom.

You can become ill with stomach flu if you:

  • touch a surface or object that contains the virus, and then touch your face or mouth
  • have close contact with someone with stomach flu
  • consume food or water that contain the virus

Norovirus in particular is resilient. It can survive for 2 weeks on surfaces and for 2 months or more in water. It can also withstand temperature changes and many common cleaning products. This can make it easier to spread from one person to another.

Although you may not be able to completely avoid these viruses, you can take steps to lower your risk, especially if someone in your household has a stomach virus.

If you currently have stomach flu, there are things that you can do to prevent the virus from spreading to other people.

Since a virus causes stomach flu, medications such as antibiotics don’t help to treat it. Typically, most people with stomach flu recover from their illness without having to seek medical treatment.

The following home remedies can help ease the symptoms of stomach flu and prevent more serious illness.

  • Drink plenty of fluids. Diarrhea and vomiting can lead to dehydration. Aim to replace lost fluids and electrolytes by regularly drinking water, sports drinks, or broths.
  • Consider an oral rehydration solution. Oral rehydration solutions contain water, electrolytes, and carbs in proportions that are easy to digest. Pedialyte is one example. These treatments may be especially helpful for children and older adults.
  • Use over-the-counter (OTC) medications. OTC medications such as bismuth subsalicylate (Pepto-Bismol) and loperamide (Imodium A-D) can help ease symptoms in adults. However, these may be unsafe for children. Talk with your child’s pediatrician about appropriate OTC medications.
  • Try bland foods. If your stomach is feeling unsettled, try to eat small amounts of bland foods such as rice, crackers, or toast.
  • Avoid foods and drinks that make symptoms worse. Some foods and drinks can make your diarrhea worse. Foods to avoid include those high in dairy, sugar, fat, or caffeine.

Although the stomach flu usually improves with self-care, it’s important to get medical attention if you notice any of the following symptoms:

Medical treatment involves managing your symptoms and promoting hydration. You may be given intravenous (IV) fluids to help replace lost fluids and electrolytes.

Depending on the severity of the above symptoms, a healthcare professional might suspect bacterial gastroenteritis instead. In this case, they may perform a stool culture or prescribe antibiotics. They may also monitor your bloodwork for signs of infection, such as a high white blood cell count.

The more accurate term for the stomach flu is viral gastroenteritis, because it’s not related to the influenza viruses that cause the respiratory illnesses we see in fall and winter. There are several types of viruses that can cause viral gastroenteritis. The most common of these is norovirus.

If you have viral gastroenteritis, you may pass the virus on to others when you have symptoms and for a few days after they go away. However, the virus can still be present in your stool for weeks after recovery. For this reason, it’s important to wash your hands thoroughly after using the restroom and before handling food or anything else that will go into your mouth.

Most people recover without seeking medical attention. However, if you experience signs of serious dehydration, blood in your stool, persistent fever, or severe abdominal pain, get medical attention right away.