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A very contagious virus transmitted from person-to-person or via contaminated food, water, or objects, causing outbreaks of vomiting and diarrhea. Norovirus is a very contagious virus that causes vomiting and diarrhea. People of all ages can get infected and sick with norovirus.

  • People with norovirus illness can shed billions of norovirus particles. And only a few virus particles can make other people sick.

  • You can get norovirus from:
  • Having direct contact with an infected person
  • Consuming contaminated food or water
  • Touching contaminated surfaces and then putting your unwashed hands in your mouth


Norovirus is the most common cause of vomiting and diarrhea, and foodborne illness.

Signs and symptoms

  • The most common symptoms of norovirus are:
  • diarrhea
  • vomiting
  • nausea
  • stomach pain
  • Other symptoms include:
  • fever
  • headache
  • body aches
  • Norovirus causes inflammation of the stomach or intestines. This is called acute gastroenteritis.
Gastroenteritis viruses
Gastroenteritis viruses


A person usually develops symptoms 12 to 48 hours after being exposed to norovirus.

  • Most people with norovirus illness get better within 1 to 3 days.

If you have norovirus illness, you can feel extremely ill, and vomit or have diarrhea many times a day. This can lead to dehydration, especially in young children, older adults, and people with other illnesses.

  • Symptoms of dehydration include:
  • decrease in urination
  • dry mouth and throat
  • feeling dizzy when standing up
  • Children who are dehydrated may cry with few or no tears and be unusually sleepy or fussy.


  • Norovirus spreads very easily and quickly in different ways.
  • Wash fruit and vegetables thoroughly
  • You can get norovirus by accidentally getting tiny particles of poop or vomit from an infected person in your mouth.
Norovirus virion 3D NIH 21350 white background
Norovirus virion 3D NIH 21350 white background

This can happen if you

  • eat food or drink liquids that are contaminated with norovirus,
  • touch surfaces or objects contaminated with norovirus then put your fingers in your mouth, or
  • have direct contact with someone who is infected with norovirus, such as by caring for them or sharing food or eating utensils with them.


If you get norovirus illness, you can shed billions of norovirus particles that you can’t see without a microscope. Only a few norovirus particles can make other people sick. You are most contagious

  • when you have symptoms of norovirus illness, especially vomiting, and
  • during the first few days after you recover from norovirus illness.
  • However, studies have shown that you can still spread norovirus for two weeks or more after you feel better.

Food poisoning

  • Norovirus spreads through contaminated food
  • Norovirus can easily contaminate food and water because it only takes a very small amount of virus particles to make you sick.

Food and water can get contaminated with norovirus in many ways, including when:

  • An infected person touches food with their bare hands that have poop or vomit particles on them
  • Food is placed on a counter or surface that has poop or vomit particles on it
  • Tiny drops of vomit from an infected person spray through the air and land on the food
  • The food is grown or harvested with contaminated water, such as oysters harvested from contaminated water, or fruit and vegetables irrigated with contaminated water in the field


  • There is no specific medicine to treat people with norovirus illness.
  • If you have norovirus illness, you should drink plenty of liquids to replace fluid lost from vomiting and diarrhea. This will help prevent dehydration.
  • Dehydration can lead to serious problems. Severe dehydration may require hospitalization for treatment with fluids given through your vein (intravenous or IV fluids).

Watch for signs of dehydration in children who have norovirus illness. Children who are dehydrated may cry with few or no tears and be unusually sleepy or fussy.


You can help protect yourself and others from norovirus by washing your hands thoroughly with soap and water and following other simple prevention tips. There is currently no vaccine to prevent norovirus; although, this is an area of active research.


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