Everyday Health

Is It the Stomach Flu or Food Poisoning?

Originally published September 24, 2019

Last updated April 26, 2024

Reading Time: 3 minutes

Is It the Stomach Flu or Food Poisoning?

Is your stomach pain from food poisoning or the stomach flu? It can be hard to tell, since both conditions share some symptoms and the two are related, which makes any confusion understandable.

Both food poisoning (foodborne illness) and the so-called stomach flu (technically it’s not the flu virus) fall under the term acute gastroenteritis, a condition in which a virus, bacterium or parasite causes inflammation in the lining of your intestines. That inflammation can lead to unpleasant symptoms, including nausea, vomiting, stomach pain or diarrhea.

“By definition, foodborne illness and stomach flu can present with the same symptoms,” says Rose Taroyan, MD, a family medicine physician at Keck Medicine of USC and clinical associate professor of family medicine at the Keck School of Medicine of USC.

There are some subtle differences, however. “If you have nausea or vomiting, stomach pain, watery or bloody diarrhea and fever after eating spoiled food or trying out a new restaurant, consider that you may have a foodborne illness. In that case, your symptoms may appear quickly — within eight to 16 hours of eating contaminated food. Your food history will provide clues, and a stool culture can sometimes provide answers,” Taroyan explains.

Stomach flu, on the other hand, is usually accompanied by diarrhea and vomiting, according to Taroyan, but it is possible to have vomiting without diarrhea. You may also see signs of dehydration. “Viral gastroenteritis typically peaks in the winter and spring months,” she adds.

The culprits behind all the trouble

Your symptoms may differ slightly, depending on what’s causing the illness. The most common way these microorganisms get into your body and disrupt your gastrointestinal system is through food contamination (hence food poisoning) or contact with someone who’s infected. Below are the causes and when their symptoms might appear, which can help you differentiate among them.

  • Norovirus
    Norovirus isn’t the same thing as the flu virus, but it’s still a virus; and according to Taroyan, it’s the most common cause of acute viral gastroenteritis. Symptoms usually set in 12 to 48 hours after contamination.
  • Staphylococcus aureus
    Staph bacteria, which are most often found in foods that typically aren’t cooked after they’re handled — such as deli meats and pastries — work fast. Within six hours (and sometimes in as little as 30 minutes), this infection will lead to vomiting, nausea, stomach cramps and diarrhea.
  • Salmonella
    By the time you experience symptoms of food poisoning from salmonella, a bacteria that thrives in foods such as raw or undercooked meat, eggs and raw fruits and vegetables, you might not even remember the food that did it. That’s because salmonella symptoms, which include stomach cramps, vomiting, diarrhea and fever, can take anywhere from 12 hours to a full three days to appear.
  • E. coli
    Presenting three to four days after contamination, symptoms caused by the E. coli bacteria are impossible to ignore. They include bloody diarrhea, severe stomach pains and vomiting. This type of food poisoning merits a trip to the doctor, as it can have serious complications.

What to do if you get sick

With the exception of E. coli, gastroenteritis typically resolves on its own, whether it’s food poisoning or stomach flu. Dehydration is the biggest cause for concern with gastroenteritis, because your body loses water through diarrhea and vomiting. For that reason, it’s important to stay hydrated.

“The ‘BRAT’ diet (bananas, rice, applesauce and toast) is very helpful to prevent dehydration,” Taroyan says.

It’s also wise to stay home from work and other activities if you’re experiencing symptoms. However, if you notice blood in your stool, a high fever, dehydration or diarrhea that lasts longer than three days, make an exception and see your doctor.

Stay ahead of the game

The best prevention against food poisoning is washing your hands with soap and water; rinsing fruits and vegetables before eating them; washing hands, knives and cutting boards after they touch raw food; and cooking foods thoroughly. To prevent getting the stomach flu, avoid those who have it. If you do come into contact with someone who has it, wash your hands frequently.


Deanna Pai
Deanna Pai is a freelance writer and editor.