Not Medical Advice: According to the Mayo Clinic, you can be contagious from a few days up to two weeks, depending on which virus is causing your stomach flu (gastroenteritis).
A number of viruses can cause gastroenteritis, including noroviruses and rotaviruses. The contagious period is slightly different for each virus.
With norovirus, you're contagious from the moment you begin to feel ill. Even if you feel better after a day or two, you're still contagious for at least three days after you've recovered. Some people may be contagious for up to two weeks after recovery. Also, children are often contagious for a longer period than are adults.
Once infected with the rotavirus, you're already contagious even before you develop symptoms, and you typically remain contagious for two weeks after you've recovered.
Viruses that cause gastroenteritis can spread through close contact with infected people, such as by sharing food or eating utensils. It is advised to wash your hands or use hand sanitizer to stop the spread of these viruses to others.
Find lifestyle tips for a healthy stomach at NHS Choices.
In health buzz, a particularly nasty strain of flu is starting to circulate, and this year's vaccine might not provide great protection against it.
A top infectious-disease expert said the strain in question is H3N2, which tends to hit elderly people the hardest and can cause dangerous complications. Nationally, about half of H3N2 viruses floating around have shifted their genes in ways that make them less than a perfect match for the current version of the flu vaccine. Find out more at The Des Moines Register.