When Is the Stomach Flu Contagious?

How is the stomach flu spread?. Image Source/Getty Images

When we have the unfortunate symptoms that come with the "stomach flu" - vomiting, diarrhea, fever, weakness, nausea, etc. - we just want them to go away. Many times I have heard people say "I wouldn't wish this on my worst enemy" yet it is often so contagious that we end up spreading it to everyone in the household.

No one likes getting sick and the "stomach flu" (which is not actually the flu, but gastroenteritis) is one of the worst.

But do you know why this illness is so contagious? Do you know how and when it is spread? Chances are good you could be spreading it without even realizing it.

Highly Contagious

Viral gastroenteritis can be caused by several different viruses. Norovirus is one of the most common. Rotavirus is another common cause that can be very serious for young children. Fortunately, there is a vaccine for rotavirus now so it is not nearly as prevalent as it used to be.

Both of these viruses and others that cause "stomach flu" symptoms are highly contagious.

Norovirus symptoms appear one to three days after exposure to the virus and you are contagious as soon as your symptoms start. General recommendations are that you can return to daily activities once you have been symptom free for 24 hours, but you are actually still contagious for three days after you recover and could spread the virus for up to 2 weeks.

With rotavirus, you are actually contagious before symptoms even appear and for two weeks after you recover. Typically symptoms start one to two days after exposure.

With both of these viruses, children are often contagious and spread the illness for longer than adults.

How Is It Spread?

Stomach bugs are spread through close contact.

Sharing utensils or food and not washing hands frequently are common reasons that the viruses spread through families. It sounds gross, but small particles of stool from diarrhea or vomit can be passed from person to person and because they are so small, you don't realize it until you are sick.

What You Can Do

Important steps to take if someone in your home is sick with gastroenteritis:

  • Wash Your Hands - especially after using the bathroom or changing diapers, before and after preparing or eating food and when caring for someone who is sick
  • Use Hand Sanitizer if soap and water isn't available
  • Wash fruits and vegetables and cook food thoroughly when someone in the house is sick
  • Don't allow sick family members to prepare food or care for others
  • Clean and disinfect surfaces in the home that could be contaminated with the virus
  • Thoroughly wash linens and clothing that came into contact with ill family members

It's often very difficult to prevent the spread of gastroenteritis through homes, day cares and other settings where many people come into close contact with one another, but taking these steps can help reduce the risk of spreading the illness.


"Preventing Norovirus Infection". Norovirus 3 Jun 14. US Centers for Disease Control and Prevention. Department of Health and Human Services. 26 Nov 14.

Steckelberg, MD, James M. "Viral Gastroenteritis (stomach flu)". Diseases and Conditions 6 Mar 12. Mayo Foundation for Medical Education and Research. 26 Nov 14.

"Viral Gastroenteritis". MedlinePlus 7 Nov 14. US National Library of Medicine. US Department of Health and Human Services. National Institutes of Health. 26 Nov 14.

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