Stomach flu is a viral infection of your intestines. The medical name for stomach flu is viral gastroenteritis. Common symptoms include:

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

Contrary to its name, the stomach flu isn’t caused by the same virus that causes the flu. In fact, there are several different types of viruses that can cause gastroenteritis.

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

Continue reading to learn more about how long the stomach flu is contagious, how it spreads, and how you can avoid getting it.

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

  • Noroviruses. Noroviruses are the most common cause. It’s estimated that they cause about 50 percent of all cases of viral gastroenteritis worldwide.
  • Rotaviruses. Rotavirus infection is more common in children. Gastroenteritis due to rotavirus is preventable by vaccination.
  • Adenoviruses. Like rotaviruses, adenovirus infections primarily affect children. However, this infection is considered to be a less common cause.
  • Astroviruses. Astroviruses also cause gastroenteritis mainly in children.

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

  • infants and young children
  • older adults
  • individuals with a weakened immune system

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

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

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

A case of the stomach flu typically resolves in less than a week. 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 your symptoms begin.

However, 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.

The viruses that cause stomach flu are present in stool and vomit. These viruses can go on to contaminate food, water, and surfaces — especially without proper hand hygiene after using the bathroom.

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 very resilient. It can survive for up to 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 greatly lower your risk, especially if someone in your household has a stomach virus.

If you currently have viral gastroenteritis, there are things that you can do to prevent the virus from spreading to others.

Since a virus causes stomach flu, medications like 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 treatments 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. It may be especially helpful for children and older adults.
  • Use over-the-counter (OTC) medications. OTC medications like bismuth subsalicylate (Pepto-Bismol) and loperamide (Imodium) can help ease symptoms in adults. However, these may be unsafe for children. Talk to your child’s pediatrician about appropriate OTC medications for symptoms.
  • 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 that make symptoms worse. Some foods 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:

  • signs of severe dehydration, such as extreme thirst, passing small amounts of urine, and dizziness
  • bloody diarrhea
  • persistent vomiting that prevents you from keeping fluids down
  • high fever
  • severe abdominal pain
  • symptoms that don’t get better or begin to get worse after several days of at-home care
  • symptoms of stomach flu that occur in an infant, older adult, or an individual with an underlying health condition

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

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, the virus may pass 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 very important to wash your hands thoroughly after using the bathroom and before handling food or anything else that will go into your mouth.

Most people recover from stomach flu 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.