Can You Get Food Poisoning From Other People?

If you have food poisoning, you or someone in your household may wonder if the symptoms are contagious. No one wants to spread illnesses to their friends, family, or co-workers. In many cases, food poisoning isn’t contagious. But there are some exceptions and situations where you can potentially spread it to others. 

It can be hard to know whether your specific case is contagious or not. So we’ll go into more detail about how food poisoning spreads and what you can do to keep the people around you safe.

What causes food poisoning? 

Food poisoning can come from many different microbes. These organisms can contaminate mishandled food or grow in food left at room temperature for too long. For example:

• Bacterial infections can develop from eating contaminated food. Many times these bacteria, like E. coli, salmonella, and Campylobacter, grow in undercooked meat. But they can also contaminate plant products. Listeria is another bacteria that commonly lives in soft cheese and deli meats.

• Bacterial toxins can also form in food. These toxins can cause symptoms of food poisoning without an actual infection. Bacteria like Staphylococcus aureus and Bacillus can make these toxins.

• Viruses can contaminate food as well. Norovirus is a common example — this is the one often associated with outbreaks on cruise ships and day cares. Hepatitis A is another example of a virus that causes food poisoning.

• Parasites are another organism that can cause food poisoning. Cyclospora and Giardia are examples.

Is food poisoning contagious from person to person? 

Food poisoning — by definition — is not contagious. It’s an illness that someone gets from eating contaminated foods. And outbreaks can occur when many people eat the same contaminated food. So, in these outbreaks, the illness isn’t spread from person to person like other infections. 

But the bacteria and viruses that cause food poisoning can spread from person to person. This is where it just becomes a matter of terminology. If person A gets sick from E. coli in their hamburger, they have food poisoning. But if they then spread that E. coli to person B, person B has gastroenteritis (“stomach flu”).

So how does food poisoning become contagious? After person A eats the contaminated hamburger, they now have a lot of harmful E. coli in their intestine. And when someone has a lot of vomiting and diarrhea, the bacteria can easily get on their hands. This is especially common right after using the bathroom (which happens a lot with food poisoning). That bacteria can then transfer to the hands of person B through direct contact or shared surfaces. And if person B then puts their hands in their mouth, it can get inside their body.

It’s also worth noting that the bacteria and viruses that cause food poisoning can also cause infections that do not start with food. Norovirus is a good example. This causes outbreaks of stomach flu, which spread like a normal virus.

Here’s the point to remember: It’s safest to assume you’re contagious if you have a case of food poisoning. This is especially true because, based on symptoms alone, it can be impossible to know which bacteria or virus is causing the illness.

How do you know if you have food poisoning?

Most people recognize the symptoms of food poisoning as soon as they start:

• Nausea

• Vomiting

• Diarrhea

• Abdominal pain and cramping

• Fever and chills

But even if you know what those telltale symptoms mean, it can be hard to know where they came from. More specifically, you may not know if the cause is from something you ate (food poisoning) or someone else (gastroenteritis). 

But looking at your recent history can help. Some clues that your symptoms are food poisoning (rather than a contagious illness) are:

• You have an idea of the food that might be to blame. For example, you may have had a noticeably undercooked hamburger or seafood that tasted off.

• Other people who ate the same food as you also got sick at the same time.

• Your symptoms started all of a sudden. A lot of the causes of food poisoning make you feel sick very quickly, usually within a few hours of a meal. Infections that spread from person to person tend to cause a more gradual onset of symptoms.

How do you know if you might be contagious?

Here’s the short answer: You won’t know for sure. It can be impossible to know for certain whether you’re contagious. This is because, most of the time, you don’t find out the exact cause of food poisoning (or whether it was truly food poisoning in the first place). Most cases of food poisoning resolve before someone sees a healthcare provider or gets any formal testing. 

If you do see your provider, they might order stool tests to see what is causing the symptoms. These tests include growing bacteria in cultures or examining the stool for signs of parasites. But even these tests don’t always find the cause. At the end of the day, for most cases of food poisoning, it’s hard to know if you’re contagious or not.

The only time food poisoning is not contagious is when the cause is a bacteria toxin (rather than a bacterial infection itself). But, again, there’s no way to know this for sure without formal testing.

Should you stay home if you have food poisoning?

Generally, it’s a good idea to stay home if you have symptoms of food poisoning. Most of the time, people don’t need specific treatments for food poisoning. But rest can be helpful (plus, you might not feel like doing anything else). This way, you can avoid spreading infections to other people if you happen to be contagious. 

So, if possible, it’s probably best to stay away from other people until you feel better. This is especially true if any of your friends or family are pregnant, immunocompromised, or very young or old. It’s also very important to stay home if you work in the service industry, as you may expose many other people. 

Why trust our experts?

Written by:

Michael Dreis, MD

Dr. Dreis is an emergency medicine physician currently practicing in Milwaukee, Wisconsin. He went to medical school at the University of Wisconsin – Madison and completed his residency at Henry Ford Hospital in Detroit, Michigan.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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