Norovirus can spread from person to person through contaminated food or water, or when a person touches a contaminated surface and transfers the virus to their mouth. While norovirus is commonly known as stomach flu, it is not, in fact, related to the seasonal flu, which is caused by the influenza virus; and it is not related to the virus that causes COVID-19. Other names for norovirus include “food poisoning” and a “stomach bug.” (2)
DiarrheaStomach painNausea and vomitingFeverHeadacheBody aches
Diarrhea and vomiting can also cause some people to become dehydrated, especially younger children, older adults, and people who have other illnesses. The symptoms of dehydration include:
Decreased urinationDry mouthDry throatDizziness when standing upCrying and fussiness in children
It’s also possible to have norovirus but not show any signs of symptoms of the illness. (3) People with the infection can release billions of norovirus particles, but it only takes a small amount of those particles to make someone sick. (4) In particular, norovirus can be transmitted by:
Eating food or drinking liquids that are contaminated with norovirus (for example, food that’s grown in contaminated water)Touching an object or surface that’s been contaminated with norovirus, then touching your mouthHaving direct contact — such as sharing food or utensils — with a person who has norovirusDrinking contaminated water from a well or from a pool that isn’t properly cleaned
More than half of all norovirus outbreaks in the United States occur in long-term care facilities. Outbreaks also occur in hospitals, restaurants, and at catered events. About 1 percent of all reported norovirus outbreaks occur on cruise ships. (5) Norovirus can also be detected in a stool sample. If you have an underlying health issue or weakened immune system, your doctor may want to order a stool test.
Prognosis of Norovirus
Most people will recover from norovirus without needing any treatment, but older adults, small children, and people with underlying medical conditions can be more susceptible to dehydration, and may therefore require medical treatment or even a hospital stay. Although the symptoms usually only last for a few days, people are contagious for much longer. Some people can keep shedding the virus in their feces for weeks — or even months, if you have underlying conditions — after recovering from the infection. (2) Because there are many different types of norovirus, you can get sick from it many times. Some people might develop an immunity to some types of norovirus, but it’s not clear how long their immunity lasts. A person’s susceptibility to norovirus is partly determined by their genetics. (6) Sports drinks or other fluids that don’t have caffeine or alcohol in them may help with mild dehydration, but your best bet is to buy over-the-counter oral rehydration fluids. If you aren’t able to drink enough liquid, or are more severely dehydrated, you may need to be given fluids intravenously, in a hospital.
Medication Options
There are no specific medicines that treat norovirus. Antibiotics don’t work against norovirus because they only fight bacteria, not viruses. (7)
Alternative and Complementary Therapies
If you’re struggling to keep food down, you might try eating bland foods, including: (2)
SoupBananasPotatoesRiceCrackers
Prevention of Norovirus
Norovirus is highly contagious, so it’s important to prevent the spread of the infection by following good hygiene practices. Some steps to take include:
Washing your hands with soap and water, especially after going to the bathroom or changing diapers (hand sanitizer isn’t a substitute for hand-washing, since alcohol is not as effective a shield against norovirus particles) (8)Washing fruits and vegetables thoroughly before eating themCooking seafood (such as oysters or other shellfish) thoroughlyCleaning and disinfecting contaminated surfaces (with a bleach-based household cleaner)Washing laundry thoroughly and handling soiled items (such as from vomit) with rubber or disposable glovesRefraining from preparing food for others if you’re sick
Some people, however, are more at risk for severe dehydration from norovirus, especially pregnant women or people who are older or have weakened immune systems. (2) According to the CDC, each year in the United States, norovirus causes an average of: (1)
19 to 21 million cases of acute gastroenteritis2,270,000 outpatient visits (these are mostly young children)465,000 emergency room visits (mostly young children)109,000 hospitalizations900 deaths
SalmonellaClostridium perfringensCampylobacterStaphylococcus aureus
Centers for Disease Control and Prevention (CDC) Learn more about norovirus and other leading causes of foodborne illnesses — including how to prevent infection — at the CDC’s website. National Foundation for Infectious Diseases (NFID) The NFID is a nonprofit organization that’s committed to educating the public about infectious diseases.
