Stomach flu is extremely contagious and can spread through person-to-person contact. A person can also catch it after coming into contact with contaminated water or food. Symptoms can pass within 3 days.

a parent is comforting a young child who has nauseaShare on Pinterest
Imgorthand/Getty Images

Stomach flu is one of several ways to refer to viral gastroenteritis.

Several viruses can cause viral gastroenteritis. According to one article, the most common virus in the United States to cause viral gastroenteritis is currently the norovirus. This accounts for 19–21 million cases per year.

In most cases, the illness is self-limiting and will clear within 1–3 days.

This article will explain how long stomach flu is contagious for and how long the symptoms can last. It will also explore the symptoms of stomach flu and when to contact a doctor and provide information on treatment and prevention methods.

Stomach flu is highly contagious.

According to the Centers for Disease Control and Prevention (CDC), a person with the norovirus is most contagious when they have symptoms of the illness, such as vomiting, and during the first few days after they have recovered.

However, they also state that a person can be contagious for up to 2 weeks following the infection.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) state that the norovirus can live on surfaces such as countertops for months.

Consuming contaminated food or water, coming into contact with bodily fluids from a person with the norovirus, and swimming in contaminated water are all ways to catch the virus.

If another virus is responsible for the infection, it may not clear up as quickly.

The NIDDK indicate the following time scales depending on the virus causing the infection:

  • Norovirus: Symptoms of this virus can last between 1 and 3 days.
  • Rotavirus: Symptoms of this virus can last between 3 and 8 days. However, it is less common in the U.S. due to vaccinations.
  • Astrovirus: Symptoms of this virus can last between 1 and 4 days.
  • Adenovirus: Symptoms of this virus can last between 1 and 2 weeks.

A person with the norovirus typically does not require treatment unless they become dehydrated.

However, they may need to go to the hospital if they do not receive proper care, and they:

  • are a young child
  • are an older adult
  • have a weakened immune system

Many symptoms of stomach flu only affect the digestive tract, but people can also experience symptoms in other areas of the body.

According to the NIDDK, stomach flu can cause symptoms such as:

Symptoms of dehydration

In many cases, dehydration can occur with stomach flu due to the amount of liquid lost during vomiting or diarrhea.

Severe cases of dehydration may require medical attention or even hospitalization.

The NIDDK warn that a person should seek treatment immediately if they experience any of the following symptoms of dehydration:

Learn how to treat dehydration here.

The norovirus can survive on surfaces such as changing tables for months. A person can also catch the virus if they come into contact with bodily fluids, such as vomit or stools, from the child.


Common symptoms of stomach flu in children may include:

Some other symptoms a child might experience include:

Dehydration in children

Parents or caregivers of children should look for the following symptoms or complaints from their children, as they can indicate dehydration.

Symptoms of dehydration in infants or children include:

  • less frequent urination or no wet diapers for 3 or more hours
  • thirst
  • dry mouth
  • lack of energy
  • sunken cheeks or eyes
  • no tears when crying
  • decreased skin turgor

Duration in children

Although children can vomit more than adults, vomiting can often stop in children after 24 hours.

If the vomiting increases after 24 hours, a parent or caregiver should contact a doctor.

If the vomiting does not stop but does not increase significantly, the parent or caregiver should try to give the child clear liquids. They should not rush trying to give the child heavier foods.

There are some steps a person can take to avoid catching stomach flu.

The most common route of infection is the fecal-oral route. In other words, most cases come from contact with infected stool.

The CDC add that a person can also catch the norovirus from:

  • contaminated foods
  • contaminated water
  • unclean surfaces

To help prevent getting stomach flu caused by the norovirus, the CDC recommend that people:

  • Avoid preparing foods for others when sick and for 2 days after the symptoms end.
  • Cook shellfish thoroughly.
  • Wash the hands frequently.
  • Rinse fruits and vegetables well.
  • Stay at home when sick and for 2 days after the symptoms end.

Learn more about how to prevent stomach flu here.

Some symptoms of stomach flu can suggest a severe case. They could also indicate dehydration or a different, potentially more serious, condition.

According to the NIDDK, a person should contact a doctor if they experience any of the following symptoms:

  • high fever
  • diarrhea lasting for longer than 2 days
  • black, tarry, or bloody stool
  • severe pain in the abdomen or rectum
  • vomiting frequently
  • six or more loose stools in a day
  • symptoms of dehydration

If a person notices a change in their or another adult or child’s mental state, including lack of energy or irritability, they should also contact a doctor.

A person should contact a doctor if their symptoms do not improve within a few days. It is possible that they have a different underlying condition.

One article recommends that people follow a bland diet when they have stomach flu and are recovering from its symptoms.

A person should also drink plenty of fluids containing electrolytes. These include low sugar sports drinks.

Read about 33 foods a person can eat with stomach flu here.

Younger children

Younger children can drink Pedialyte to consume fluid with electrolytes.

However, the NIDDK recommend avoiding drinks that contain excessive amounts of sugar, such as fruit juice and soda, since sugar can make diarrhea symptoms worse.

A common cause of stomach flu is the norovirus. However, other viruses, bacteria, parasites, and chemicals can also cause it to occur.

Stomach flu symptoms are mainly related to the digestive tract and can cause vomiting and diarrhea.

Symptoms of stomach flu can last between 1 day and 2 weeks, depending on the cause. Norovirus symptoms usually pass within 3 days. A person is contagious while they have symptoms.

A person should seek symptom relief within a few days and should use caution for several days following symptoms, since they may still be contagious at that point.

A person should contact a doctor if they experience any symptoms of dehydration or any worsening symptoms that do not clear or start to get better within a few days.