If a person knows several people experiencing vomiting, abdominal cramps, or diarrhea, there may be a stomach bug going around in their area.

Stomach bugs are common illnesses that can spread quickly. In the United States, there are approximately 2,500 norovirus outbreaks per year. Norovirus is the most common cause of stomach bugs.

In the northern hemisphere, stomach bug outbreaks happen more in the colder months between November and April. Most people recover at home without medical treatment, but medical care may be necessary if there are complications.

This article explains how to tell a stomach bug is going around, when and where stomach bugs are most common, and how many people get them.

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Stomach bugs, or viral gastroenteritis, cause similar symptoms in people of all ages. These include:

If several people who have recently been in close contact with each other develop these symptoms in quick succession, it may be due to a stomach bug.

Another sign there may be an outbreak in the area include a higher-than-typical number of absences in a school or workplace. People may also hear about outbreaks through word of mouth.

However, it is important to note that many illnesses cause nausea, vomiting, and diarrhea. This includes other infectious diseases, such as COVID-19.

Learn more about the differences between stomach bugs, food poisoning, and COVID-19.

Stomach bugs usually occur due to viral infections. Different viruses are more common at different times of the year. There are also viruses that affect certain age groups and settings more than others.


The most common cause of stomach bugs is norovirus. This virus can spread at any time of the year, but it is more frequent in the colder months between November and April.

Some settings especially prone to norovirus outbreaks include:

  • long-term care facilities
  • hospitals
  • restaurants
  • schools
  • day care centers
  • cruise ships


Rotavirus can cause stomach bugs throughout the year, but it happens more often in the winter and spring.

Children are the most at risk from this virus, particularly if they have not received a rotavirus vaccine. The most severe cases occur in unvaccinated children between 3 months and 3 years old.

Some adults also have a higher risk of severe symptoms, including:


There are many types of adenovirus, two of which can cause gastroenteritis in children. According to a 2020 review, some research suggests that adenovirus outbreaks are not seasonal, while other studies suggest they occur more in summer and fall.


Astrovirus outbreaks often occur in winter. This type of virus is most associated with children, but it can also affect older adults and people with weakened immunity.


Sapovirus can occur at any time of the year and affect any age group. However, it most often affects children under the age of 5.

A 2022 research article notes that norovirus causes 19–21 million cases of diarrhea in the United States per year.

There are approximately 2,500 outbreaks each year, and the virus is responsible for 900 deaths per year, mostly among older adults.

Before the advent of the rotavirus vaccine in 2006, almost all children got rotavirus infections before 5 years old. Outbreaks have since become significantly less common, but they can still happen in places with low vaccination rates.

The duration of stomach bugs varies depending on the cause, among other factors. The table below lists how long symptoms usually last:

VirusTypical duration
norovirus1–3 days
rotavirus3–8 days
adenovirus1–2 weeks
astrovirus1–4 days
sapovirus1 week

In most cases, stomach bugs improve on their own at home without treatment. Here are some things that may help.

Fluid and electrolytes

Replacing the fluids people lose through vomiting and diarrhea can help prevent dehydration. Replacing electrolytes is also important. Electrolytes are salts and minerals that play an essential role in the body.

Adults can replace lost fluids by drinking:

  • water
  • sports drinks
  • fruit juices
  • broths

Eating saltine crackers is also beneficial for restoring electrolytes.

In other situations, an oral rehydration solution may be necessary. These include products such as Naturalyte or Pedialyte, which have the right balance of liquid and electrolytes for the body.

Children, older adults, and people with weaker immune systems can benefit from these drinks.

Over-the-counter (OTC) medications

OTC medications, such as bismuth salicylate (Pepto Bismol) or loperamide (Imodium), may help some adults reduce the symptoms of a stomach bug.

However, people with signs of a bacterial infection, such as a fever or bloody diarrhea, should avoid these medications. They are also not safe for infants and children.

Medical treatment

If the symptoms of a stomach bug are severe, or a person is showing signs of dehydration, medical treatment may be necessary.

The symptoms of dehydration include:

Young children may also appear lethargic, have a soft depression on the top of their heads, or have sunken eyes and cheeks.

People with dehydration who cannot keep fluids down should go to an emergency room for treatment. People should also take children for immediate treatment if they have dehydration or oral rehydration fluids do not help.

If a person has a high fever, abdominal pain, bloody vomit or diarrhea, or does not get better on their own, seek help from a doctor right away.

The only way to avoid getting a stomach bug is through prevention. The Centers for Disease Control and Prevention (CDC) recommend:

  • washing the hands frequently, especially:
    • after changing diapers or using the toilet
    • before preparing food or eating
    • before taking medication
  • taking care to wash and cook foods thoroughly before eating, particularly:
    • shellfish
    • vegetables
    • fruits
  • disposing of any possibly contaminated food

It is also advisable for people to clean and disinfect high touch surfaces regularly, such as door handles and light switches.

If a person is caring for someone else with a stomach bug, they should:

  • immediately clean and disinfect any areas where a person has vomited or had diarrhea using a bleach-based cleaning product
  • immediately remove and launder linens or clothing that may be contaminated
  • keep the person at home while they are sick and for at least 2 days after symptoms disappear
  • keep them away from the kitchen or other food preparation areas for at least 2 days after symptoms stop

If possible, people should also wear rubber gloves when cleaning anything that may have come into contact with the virus, or while handling soiled laundry.

If a person knows several people who have diarrhea or vomiting, a stomach bug may be going around in their area. Absences from schools or workplaces, and hearing about people becoming ill who have been in close contact with each other, could also indicate an outbreak.

The most common cause of stomach bugs in the U.S. is norovirus. Norovirus is more frequent during the colder months and in settings where groups of people mix closely together, such as long-term care facilities, schools, and cruise ships.

People usually recover from stomach bugs without medical treatment, but it is important to stay hydrated and replace lost electrolytes.

OTC medications such as loperamide (Imodium) may help some adults, but a person should check with a doctor or pharmacist before taking these, as they can interact with some medications.