Norovirus Infection

Norovirus illness is caused by a viral infection. The term norovirus refers to a group of viruses. Any of those viruses can cause norovirus illness. This illness is often referred to by other names such as viral gastroenteritis, stomach flu, and food poisoning. Anyone can get a norovirus infection. People can have the illness multiple times during their lifetime.


Norovirus is found in the stool or vomit of infected people. It is easily spread from person to person (contagious). People with norovirus are contagious from the moment they begin feeling ill. They may remain contagious for as long as 3 days to 2 weeks after recovery.

People can become infected with the virus in several ways. This includes:

  • Eating food or drinking liquids that are contaminated with norovirus.

  • Touching surfaces or objects contaminated with norovirus, and then placing your hand in your mouth.

  • Having direct contact with a person who is infected and shows symptoms. This may occur while caring for someone with illness or while sharing foods or eating utensils with someone who is ill.


Symptoms usually begin 1 to 2 days after ingestion of the virus. Symptoms may include:

  • Nausea.

  • Vomiting.

  • Diarrhea.

  • Stomach cramps.

  • Low-grade fever.

  • Chills.

  • Headache.

  • Muscle aches.

  • Tiredness.

Most people with norovirus illness get better within 1 to 2 days. Some people become dehydrated because they cannot drink enough liquids to replace those lost from vomiting and diarrhea. This is especially true for young children, the elderly, and others who are unable to care for themselves.


Diagnosis is based on your symptoms and exam. Currently, only state public health laboratories have the ability to test for norovirus in stool or vomit.


No specific treatment exists for norovirus infections. No vaccine is available to prevent infections. Norovirus illness is usually brief in healthy people. If you are ill with vomiting and diarrhea, you should drink enough water and fluids to keep your urine clear or pale yellow. Dehydration is the most serious health effect that can result from this infection.

By drinking oral rehydration solution (ORS), people can reduce their chance of becoming dehydrated. There are many commercially available pre-made and powdered ORS designed to safely rehydrate people. These may be recommended by your caregiver.

Replace any new fluid losses from diarrhea or vomiting with ORS as follows:

  • If your child weighs 10 kg or less (22 lb or less), give 60 to 120 ml (¼ to ½ cup or 2 to 4 oz) of ORS for each diarrheal stool or vomiting episode.

  • If your child weighs more than 10 kg (more than 22 lb), give 120 to 240 ml (½ to 1 cup or 4 to 8 oz) of ORS for each diarrheal stool or vomiting episode.


  • Follow all your caregiver's instructions.

  • Avoid sugar-free and alcoholic drinks while ill.

  • Only take over-the-counter or prescription medicines for pain, vomiting, diarrhea, or fever as directed by your caregiver.

You can decrease your chances of coming in contact with norovirus or spreading it by following these steps:

  • Frequently wash your hands, especially after using the toilet, changing diapers, and before eating or preparing food.

  • Carefully wash fruits and vegetables. Cook shellfish before eating them.

  • Do not prepare food for others while you are infected and for at least 3 days after recovering from illness.

  • Thoroughly clean and disinfect contaminated surfaces immediately after an episode of illness using a bleach-based household cleaner.

  • Immediately remove and wash clothing or linens that may be contaminated with the virus.

  • Use the toilet to dispose of any vomit or stool. Make sure the surrounding area is kept clean.

  • Food that may have been contaminated by an ill person should be discarded.


  • You develop symptoms of dehydration that do not improve with fluid replacement. This may include:

  • Excessive sleepiness.

  • Lack of tears.

  • Dry mouth.

  • Dizziness when standing.

  • Weak pulse.