How long am I contagious if I have the stomach flu?

Answers from James M. Steckelberg, M.D.

You can be contagious from a few days up to two weeks or more, depending on which virus is causing your stomach flu (gastroenteritis). A number of viruses can cause gastroenteritis, including noroviruses and rotaviruses. The contagious period — the time during which a sick person can give the illness to others — is slightly different for each virus.

  • Norovirus. With norovirus — the most common cause of viral gastroenteritis in adults and children — you're contagious from the moment you begin to feel ill. Symptoms usually appear within one to two days of exposure. Although you typically feel better after a day or two, you're contagious for up to three days after you've recovered. Some people may be contagious for up to two weeks after recovery.
  • Rotavirus. Symptoms of rotavirus — the leading cause of viral gastroenteritis in infants and young children — usually appear one to three days after exposure. But you're contagious even before you develop symptoms, and up to two weeks after you've recovered.

The viruses that cause gastroenteritis are spread through close contact with infected people, such as by sharing food or eating utensils, and by touching contaminated surfaces and objects. Washing your hands often with soap and water and using hand sanitizer is the most effective way to stop the spread of these viruses to others.

Two oral rotavirus vaccines are available for young infants — RotaTeq and Rotarix.

Jan. 17, 2015 See more Expert Answers