How Long Is Stomach Flu Contagious?

Norovirus, sometimes called "the stomach flu," is very contagious. You can spread the virus the whole time you're sick, but you’re the most contagious while you’re having symptoms.

You can still spread the stomach flu even when you’re starting to feel better. Depending on the severity of your symptoms, the contagious period for the stomach flu can last from a few days up to a few weeks.

The amount of time that you can spread the stomach flu depends on what germ is making you sick, since norovirus is not the only pathogen that causes symptoms of the stomach flu. This article looks at how long the stomach flu is contagious and how many days you should stay home if you get sick. 

Stomach Flu Contagiousness by Cause

The viruses and bacteria that cause gastroenteritis (the medical term for stomach flu) can be contagious for different amounts of time.

The cause of the stomach flu will determine when symptoms will start, how long they'll last, and the length of time you'll be able to spread the illness to other people. You may pass on the stomach flu to someone else before you even know you have it or well after you think you’ve gotten over it. 

Here's a look at four common causes of the stomach flu and how long they are contagious by stage.

Norovirus is one of the most contagious infectious illnesses around. It only takes a few particles to make you sick, and you can start having symptoms within one to two days of being exposed. You’ll be contagious while you’re having symptoms and for up to 2 weeks after you start feeling better.

Rotavirus is a common cause of stomach flu, especially in kids. You’ll usually start having symptoms within two days of being exposed to someone who is sick and can spread it to other people while you’re having symptoms and for up to 10 days after you recover.

“Food poisoning” is a broad term for the “stomach flu” you get from eating or drinking something contaminated with certain bacteria, like campylobacter or E. coli.

Campylobacter symptoms usually start two to five days after you’ve been exposed and can last for up to a week. While it’s not common to spread this infection to other people, if you’re having diarrhea, it is possible for the infection to spread to others—especially if you don’t wash your hands after using the bathroom. 

E. coli symptoms come on within three to four days of being exposed, and you may have symptoms for a week to 10 days. During that time, you’ll be able to get other people sick.

How Long Should You Stay Home With the Stomach Flu?

Follow your healthcare provider's advice on how long you should stay home with the stomach flu.

In general, you should stay home for as long as you have symptoms of the stomach flu and for between 24 hours and 48 hours after your symptoms go away.

If you’re running a fever, you’re definitely contagious. But even without a fever, stomach viruses are easy to spread.

You may want to go back to work or send your child to school once the vomiting or diarrhea has stopped, but it’s important to wait the full 24 hours after the last episode of symptoms to leave home to make sure you aren’t going to spread the stomach flu to others. 

Your symptoms are unlikely to come back once they’ve been gone for 24 hours (though it's possible). 

How Stomach Flu Is Spread

Norovirus, one of the most common causes of the stomach flu, can live on surfaces for about two to four weeks. Since it can survive so long outside the body, it makes it easy to spread. The stomach flu is usually spread by the fecal-oral route—the accidental ingestion of infected stool.

This can come from:

• Consuming contaminated food or water
• Touching contaminated objects or surfaces
• Coming into close contact with an infected person

How to Prevent Passing the Stomach Flu to Others

One of the most effective ways to prevent the stomach flu from spreading or at least greatly reduce the chances of getting someone else sick is washing your hands frequently and often. 

Here are other stomach flu prevention steps you can take at home:

• Do not share objects like cups and utensils with others.
• Keep your clothes and bedding clean and wash them separately from other people in your house.
• Use a separate bathroom, if possible, and disinfect surfaces you touch (like doorknobs).
• Do not make or share food with other people.

To prevent stomach flu caused by food-borne illness, always practice food safety steps like:

• Washing produce 
• Cooking all meat to the correct internal temperature and check with a meat thermometer
• Keeping your kitchen surfaces and tools clean
• Not using the same implements (like cutting boards) for raw meat and other foods, like veggies 
• Storing leftovers properly (within two hours) and throw them out if they look or smell unusual 
• Checking expiration dates on foods 
• Keeping perishable items in the fridge or freezer and make sure that they are kept cool enough (refrigerators should be at 40F or less and freezers at 0F)
• Thawing frozen foods properly

When to Call a Healthcare Provider

Staying home doesn’t just help you avoid spreading the stomach flu to others; it also gives you the chance to rest and stay hydrated. 

Usually, that’s all you need to do to get over a bout of the stomach flu. However, you should call your healthcare provider or go to your nearest urgent care center if you have the stomach flu and you:

• Cannot keep down fluids for more than 24 hours
• Have a fever over 104 degrees F
• Have been vomiting for more than two days
• Have signs of severe dehydration
• Have bloody stools
• Have bloody vomit

Summary

Stomach viruses are very contagious. You can spread them before symptoms start and for up to two weeks after you feel better.

You should stay home for 24 to 48 hours after symptoms like vomiting, diarrhea, and fever have stopped. 

The best way to prevent the spreading of stomach flu viruses like norovirus and rotavirus is to wash your hands often and stay away from others until you’re sure you’re no longer contagious. Taking general prevention steps like practicing food safety can help prevent stomach flu caused by foodborne illness.