Norovirus is the term for a group of viruses that causes severe vomiting and diarrhea. It is very common and very easy to spread (contagious). It can spread through infected people, contaminated food, or contaminated surfaces. While many people call norovirus “the stomach flu,” it has no relation to the flu (influenza).
People can become infected with norovirus in many ways. You can get the virus through close contact with someone who is sick, by touching contaminated surfaces and then touching your mouth, or by eating or drinking contaminated foods or water.
Norovirus is the biggest cause of illness from contaminated food in the U.S. The virus typically spreads when an infected food worker touches food before serving it. Sometimes certain foods, including oysters and other seafood, are naturally contaminated with norovirus.
Norovirus can make you feel very sick. Symptoms usually appear 12 to 48 hours after your exposure to the virus and last 2 or 3 days. These symptoms can appear suddenly and include:
Your doctor can usually diagnose norovirus by talking to you about your symptoms. The virus can also be confirmed through testing of a stool sample. Most of the time, this test is not needed.
There is no treatment to cure norovirus. But you can take steps to ease symptoms while the virus runs its course. These include:
Norovirus often spreads quickly in closed places where many people gather, such as schools, cruise ships, and nursing homes. Most cases happen during the winter and early spring months. Some everyday precautions you can take to reduce your risk of getting the virus include:
Most people with norovirus feel better after 2 or 3 days, with no long-term effects. Because norovirus includes many different types of viruses, you can get the illness more than once. Some people get it several times throughout their lifetime.
Norovirus can be present in your stool both before symptoms start and for 2 weeks after the symptoms stop.
Last reviewed by a Cleveland Clinic medical professional on 01/25/2018.