Image of a young woman in pain holding her stomach due to either food poisoning or gastroenteritis


Feeling sick to your stomach? There’s probably one question hanging over your head as you’re hanging over the edge of the toilet: Is it a virus or is it something you ate? On the surface, stomach viruses and food poisoning look and feel so much alike to their victims that trying to tell them apart can be as nauseating as the ailments themselves. Believe it or not, the symptomatic twinning isn’t just a coincidence; there’s actually a medical explanation for it:

“It is often difficult to distinguish between food poisoning and gastroenteritis, [a.k.a. the stomach bug], because the same types of bacteria or viruses can live on food or on humans, hence resulting in similar types of illnesses,” says Ketan Shah, M.D., gastroenterologist at Saddleback Medical Center in Laguna Hills, Calif.

But take a close enough look and you just might spot the subtly unique characteristics that set each condition apart. Being able to make the distinction between the two is important, since unaddressed stomach probs can lead to more than just losing your lunch: “Certain food-borne illnesses can become very serious and sometimes life-threatening if unrecognized or untreated,” says Bhavesh Shah, M.D., medical director of interventional gastroenterology at Long Beach Medical Center.

Here, we break down the differences and similarities between food poisoning and the stomach virus so you don’t have to play a nasty game of “What’s making me hurl?” Because, seriously, ain’t nobody got time for that.

The Causes

You might be thinking, “Duh, this is obvious: Food poisoning is caused by food, and stomach flu is caused by a virus. Bam.” Well, in actuality, things are a bit more complicated than that. Let’s start with how they’re alike: According to Ketan Shah, both illnesses are caused by exposure to either bacteria or a virus. The fork in the road appears when you start considering how you’re exposed to that bacteria or virus.

“Food poisoning happens when you ingest a food-borne pathogen, and gastroenteritis happens as a result of any type of exposure—usually from person to person—such as exposure to infected people, bodily fluids, clothes, surfaces, as well as food,” says Ketan Shah. “The most common pathogens in food poisoning are norovirus, Salmonella, Campylobacter, Clostridium perfringens, E. coli and Staphylococcus aureus. The most common pathogens in gastroenteritis are viruses (especially norovirus), Salmonella and Campylobacter.”

Try to retrace your steps. Did you come into close contact with someone who just got over a stomach bug over the last couple of days? Forget to wash your hands after touching a germy train pole? Then the bug might be to blame.

The Symptoms

This is where you’ll find more similarities than differences between these gut-wrenching ailments. According to Ketan Shah, food poisoning and gastroenteritis share most symptoms, which include abdominal cramps, fever, chills, nausea, decreased appetite, diarrhea, muscle or joint aches, headaches, and, of course, vomiting. The key to discerning between the two is paying attention to when they manifest and for how long.

“Due to the types of pathogens that result in these conditions, symptoms from food poisoning generally develop a few to several hours after exposure [to contaminated food], whereas symptoms from gastroenteritis usually develop 24 to 48 hours after exposure [to the virus],” says Ketan Shah. So if your gut’s feeling under the weather, think back on anything questionable you might have eaten on the same day of your symptom onset. Ate a big lunch at that new seafood place last night only to be tossing it up by nighttime? Then you might have found your culprit.

Make sure you also keep tabs on how long your symptoms are lasting: When your stomach’s in knots for more than a few days, that’s a clue that you probably don’t have food poisoning. “A bacterial, parasitic, or viral gastroenteritis can last an average of one week,” says Toyia James-Stevenson, M.D., gastroenterologist at Indiana University Health.

The Treatments

“Remaining hydrated and keeping your electrolytes within normal limits is the recommended treatment for both of these illnesses,” says Bhavesh Shah. This is what’s referred to as “conservative management” in doctor speak. Water and electrolyte solutions, like Gatorade, Powerade, or Pedialyte are also best for keeping your fluid levels in check. Avoid sugar-packed soft drinks and juices, which could upset your stomach even more and worsen diarrhea. “Most patients tolerate a light, bland BRAT diet [(i.e., bananas, rice, applesauce, and toast)] better during their illness, but otherwise should continue with what is tolerated,” he continues.

If you have no luck managing your condition, no matter what it is, with watchful food and fluid intake, Ketan Shah recommends that you speak with your physician about further evaluation—especially if you experience signs of dehydration (like dizziness, lightheadedness, or decreased urine output), bloody stools, severe abdominal pain, or weight loss.

For gastroenteritis, doctors may also prescribe anti-vomiting or anti-nausea medications if you have significant trouble keeping any food down, or they might even give you intravenous fluids if you become severely dehydrated. Antibiotics are rarely given for a stomach bug or food poisoning.