norovirus, winter vomiting bug
Norovirus is highly contagious, and vomiting and diarrhea can cause severe hydration in children

Norovirus, also called the winter vomiting bug, is a highly contagious virus that causes sudden, severe vomiting and diarrhea

It spreads easily and is the most common cause of gastroenteritis. Spread of the virus occurs through food, water, contaminated surfaces, and contact with an infected person.

What are signs and symptoms of norovirus?

Norovirus causes inflammation of the stomach or intestines. Signs and symptoms usually begin 12 to 48 hours after exposure to norovirus and last for 1-3 days. 

Some people with norovirus infection show no signs or symptoms but are still contagious and can spread the virus to others. An infected person can continue to shed the virus in their feces for up to 2 weeks after recovery. 

The most common symptoms of norovirus are:

Other symptoms include:

What causes norovirus infection?

People infected with norovirus can release billions of norovirus particles into the air, and it only takes a few of these particles to make a person fall sick. The most common cause of transmission includes:

  • Shellfish
  • Contaminated foods
  • Ready-to-eat foods, such as salads, ice, cookies, fruit, and sandwiches, that have been handled by a worker with a norovirus infection
  • Any food that contains particles of the feces or vomit of a person with norovirus
  • Touching surfaces or objects contaminated with norovirus and then touching the mouth

What are risk factors for norovirus infection?

Noroviruses are difficult to kill off because they can withstand hot and cold temperatures and most disinfectants. Risk factors for becoming infected with norovirus include:

  • Having a weakened immune system (for example, people who have undergone an organ transplant and individuals living with HIV are more susceptible to the disease)
  • Living with people who do not correctly observe food hygiene practices
  • Living with a child who attends a childcare center or preschool
  • Staying in a hotel, cruise ship, or vacation resort where many people congregate
  • Living in a closed or semi-closed community, such as a nursing home, hospital, or retirement center

How is norovirus treated?

There is no specific treatment for norovirus infection and recovery generally depends on the health of a person's immune system. Most people recover completely without treatment. 

However, for some people, especially infants, older adults, and people with underlying diseases, vomiting and diarrhea can cause severe dehydration, which requires medical attention. It's important to replace lost fluids and use oral rehydration solutions to rehydrate the body.

How to prevent norovirus from spreading

Lifestyle changes can help to prevent the spread of infection:

  • Handwashing after going to the bathroom, changing a diaper, and before preparing meals
  • Cleaning surfaces with a bleach-based household cleaner
  • Avoiding risky foods, such as shellfish, which may come from contaminated waters
  • Removing infected feces and vomit
  • Washing clothing and bedclothes
  • Keeping the toilet seat down when flushing
  • Staying at home and avoiding public contact
  • Using disposable towels
  • Taking precautions when traveling


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Medically Reviewed on 6/16/2021
Centers for Disease Control and Prevention. About Norovirus.

National Health Service. Norovirus (Vomiting Bug).

Khan ZZ. Norovirus. Medscape.