Norovirus (the stomach bug)

Norovirus is a highly contagious virus. Norovirus infection causes gastroenteritis (inflammation of the stomach and intestines). This leads to diarrhea, vomiting, and stomach pain.

Norovirus illness is often called by other names, such as food poisoning and stomach flu. Noroviruses can cause food poisoning, as can other germs and chemicals. Norovirus illness is not related to the flu (influenza). Though they share some of the same symptoms, the flu is a respiratory illness caused by influenza virus.

Anyone can get norovirus illness

  • Norovirus is the most common cause of acute gastroenteritis in the U.S.
  • Each year, norovirus causes 19 to 21 million cases of acute gastroenteritis in the U.S.
  • There are many types of norovirus and you can get it more than once.

Norovirus illness can be serious

  • Norovirus illness can make you feel extremely sick with diarrhea and vomiting many times a day.
  • Some people may get severely dehydrated, especially young children, the elderly, and people with other illnesses.
  • Each year, norovirus causes 56,000 to 71,000 hospitalizations and 570 to 800 deaths, mostly in young children and the elderly.

Norovirus spreads very easily and quickly

  • It only takes a very small amount of norovirus particles (fewer than 100) to make you sick.
  • People with norovirus illness shed billions of virus particles in their stool and vomit and can easily infect others.
  • You are contagious from the moment you begin feeling sick and for the first few days after you recover.
  • Norovirus can spread quickly in enclosed places like daycare centers, nursing homes, schools, and cruise ships.
  • Norovirus can stay on objects and surfaces and still infect people for days or weeks.
  • Norovirus can survive some disinfectants, making it hard to get rid of.

Norovirus can spread in many ways

Norovirus can spread to others by—

  • having direct contact with an infected person, for example, touching an infected person while caring for them,
  • eating food or drinking liquids that are contaminated with norovirus,
  • touching objects that have norovirus on them and then putting your fingers in your mouth, for example, touching a countertop that has vomit droplets on it and then putting your fingers in your mouth and sharing utensils or cups with people who are infected with norovirus.

There’s no vaccine to prevent norovirus infection and no drug to treat it

  • Antibiotics will not help with norovirus illness because antibiotics do not work on viruses.
  • When you have norovirus illness, drink plenty of liquids to replace fluid loss and prevent dehydration.
  • If you or someone you are caring for is dehydrated, call a doctor.

What is the Right Way to Wash Your Hands?

  1. Wet your hands with clean, running water (warm or cold) and apply soap.
  2. Rub your hands together to make a lather and scrub them well; be sure to scrub the backs of your hands, between your fingers, and under your nails.
  3. Continue rubbing your hands for at least 20 seconds. Need a timer? Hum the “Happy Birthday” song from beginning to end twice.
  4. Rinse your hands well under running water.
  5. Dry your hands using a clean towel or air dry them.

See Handwashing: Clean Hands Saves Lives (

5 Tips to Prevent Norovirus From Spreading

1. Practice proper hand hygiene

Always wash your hands carefully with soap and water—

  • after using the toilet and changing diapers, and
  • before eating, preparing, or handling food.

Alcohol-based hand sanitizers can be used in addition to hand washing. But, they should not be used as a substitute for washing with soap and water.

2. Wash fruits and vegetables and cook seafood thoroughly

Carefully wash fruits and vegetables before preparing and eating them. Cook oysters and other shellfish thoroughly before eating them.

Be aware that noroviruses are relatively resistant. They can survive temperatures as high as 140°F and quick steaming processes that are often used for cooking shellfish.

Food that might be contaminated with norovirus should be thrown out.

Keep sick infants and children out of areas where food is being handled and prepared.

3. When you are sick, do not prepare food or care for others

You should not prepare food for others or provide healthcare while you are sick and for at least 2 to 3 days after you recover. This also applies to sick workers in schools, daycares, and other places where they may expose people to norovirus.

4. Clean and disinfect contaminated surfaces

After throwing up or having diarrhea, immediately clean and disinfect contaminated surfaces. Use a chlorine bleach solution with a concentration of 1000–5000 ppm (5–25 tablespoons of household bleach [5.25%] per gallon of water) or other disinfectant registered as effective against norovirus by the Environmental Protection Agency (EPA).

5. Wash laundry thoroughly

Immediately remove and wash clothes or linens that may be contaminated with vomit or stool (feces).

You should—

  • handle soiled items carefully without agitating them,
  • wear rubber or disposable gloves while handling soiled items and wash your hands after, and wash the items with detergent at the maximum available cycle length then machine dry them.

Disease Information

Information to help control the spread of disease and to protect others from getting it.



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