Norovirus: The stomach bug

Norovirus is the virus that causes gastroenteritis (inflammation of the stomach and intestines). This leads to diarrhea (loose stools), vomiting (throwing up), and stomach pain. 

It is often called by other names, such as food poisoning and stomach flu. It can cause food poisoning, but other germs can too.

It is not the same as the flu (influenza). Though they share some of the same symptoms, the flu is a respiratory illness caused by influenza virus.

Any person can get norovirus.

  • It is the most common cause of gastroenteritis in the U.S.
  • There are many types of norovirus, and you can get it more than once.

Norovirus can be serious.

  • It can make you feel very sick with diarrhea.
  • You might throw up many times a day.
  • Some people may get very dehydrated (fluid loss). People at highest risk are:
    • Young children
    • Older people
    • People with other illnesses

How is norovirus spread?

It spreads quickly and easily.

  • It only takes a very small amount of norovirus particles (less than 100) to make you sick.
    • It is found in loose stools and vomit. It is easy to get others sick.
  • You can spread it to people from the moment you start feeling sick and for the first few days after you get better.
  • It can spread quickly in places like daycares, nursing homes, schools, and cruise ships.
  • It can stay on objects and surfaces. It can still get people sick days or weeks later.
  • It can survive cleaning products and make it hard to get rid of.

It is spread to others by:

  • Having direct contact with a sick person, such as:
    • Touching a sick person while caring for them
  • Eating food or drinking liquids that are contaminated
  • Touching objects that have norovirus on them and then putting your fingers in your mouth, such as:
    • Touching a countertop that has vomit droplets on it then putting your fingers in your mouth
  • Sharing silverware or cups with people who are sick

How is norovirus treated?

  • There is no vaccine to prevent norovirus and no medicine to treat it.
    • Antibiotics do not work on viruses and will not help.
  • Drink a lot of liquids to replace fluid loss and stop dehydration.
    • Call a doctor if you or someone you are caring for is dehydrated.

In the hospital

  • Staff will wear gowns and gloves (contact isolation precautions) to keep norovirus from spreading.
  • Your care team will decide when you no longer need to be on isolation precautions.

Washing your hands in the hospital

Wash your hands:

  • After using the bathroom
  • Before eating
  • Before leaving your room

Visitors should:

  • Wash their hands each time they enter or leave your room
  • Not sit on your bed or use your bathroom

Follow any instructions given to help stop infections.

Washing your hands at home

  • Wash your hands with soap and water (not alcohol-based hand rubs) for at least 15 seconds (or as long as it takes to sing the “happy birthday” song twice):
    • After using the toilet
    • Changing diapers
    • Before eating, cooking, touching food

Eating at home

  • Wash fruits and vegetables before cooking and eating them.
    • Fully cook all foods before eating them.
  • Food that might be contaminated with norovirus should be thrown out.
  • Keep sick babies and children out of places where food is being handled and cooked.

Living at home

  • Do not cook food or care for others:
    • When you are sick
    • For at least two to three days after you are better
  • This also applies to sick workers in schools, daycares, and other places where you may spread it to people.

Cleaning at home

  • Clean and disinfect contamined surfaces after throwing up or having loose stools.
    • Use a chlorine bleach solution.
  • Wash all bathroom surfaces with bleach:
    • Bathtub
    • Shower
    • Toilet seat and flush handle
    • Sink



Last reviewed: 
July 2017

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