Food Poisoning or Stomach Flu? How to Tell the Difference

You and your family enjoyed a lovely meal with friends, but now, shortly after, everyone feels queasy and is running for the bathroom. Everyone is experiencing symptoms of diarrhea, nausea and vomiting, and some have fever, chills and headaches. Your mind wanders back to the meal—did a friend give you a stomach bug, or was there something not quite right about the meat or the deviled eggs?

Because food poisoning and the stomach flu can present with similar symptoms, it can be difficult to tell them apart. UNC Health family medicine doctor LeRon Jackson, MD, provides insight as to which condition is causing the trips to the toilet, and what to do when you’re feeling sick.

Key Differences: Food Poisoning vs. Stomach Flu

“While the symptoms of food poisoning and stomach bugs overlap, there is a difference in how quickly the symptoms arise,” Dr. Jackson says. “With food poisoning, rapid diarrhea and vomiting will begin within three to six hours of eating a contaminated food source. With a stomach flu, it’s a slower course, and the symptoms of vomiting and diarrhea may not show up for 12 to 24 hours. A person will start feeling unwell and queasy first.”

If your entire family is sick only a few hours after a barbecue or eating at the same restaurant, then you’re probably the victim of food poisoning, which occurs when food isn’t prepared, refrigerated or washed properly, resulting in bacterial, viral or parasitic contamination. If the meal was a few days ago, then your condition is more likely stomach flu, which is usually caused by different viruses, such as noroviruses and rotaviruses. Stomach flu and stomach bugs are more properly known as gastroenteritis, and a stomach flu is different from influenza, which is a respiratory infection.

Food poisoning and stomach flu also differ in the time they take to run their course. “Food poisoning is over pretty quickly—24 to 48 hours, max,” Dr. Jackson says. “You might still feel a little fatigued, but the diarrhea and vomiting should be over. For stomach flu, it will usually take three to five days to feel better.”

Food Poisoning and Stomach Flu Treatment

Although the duration of food poisoning and stomach flu may differ, the treatment for both is similar. Rest and hydrate by drinking lots of water and beverages with electrolytes.

“If you have little kids, let them hydrate in whatever way they can,” Dr. Jackson says. “Popsicles, Jell-O, ice chips, slushies—anything fun or appealing to the child that will help them to get fluids.”

If you are regularly vomiting, consume clear fluids, including broths, until the vomiting has ended. If you are mostly experiencing diarrhea, however, you can eat food that will thicken and slow stool. Dr. Jackson recommends starting with the BRAT diet—short for bananas, rice, applesauce and toast—and then expanding to other foods.

Dr. Jackson says to avoid antidiarrheal medications unless they are recommended by a healthcare professional.

“With a symptom like diarrhea, your body is trying to remove a bacterial or viral presence from your system. Taking an antidiarrheal can slow that removal,” she says.

If one person in your family is experiencing a stomach bug, it’s important to take steps to reduce the spread of infection by disinfecting high-touch surfaces—such as doorknobs, kitchen counters and TV remotes—and washing hands. Don’t share food, beverages or utensils with a sick person.

When to Seek Medical Help for Stomach Flu and Food Poisoning

Most healthy people can manage food poisoning and the stomach flu at home, as long as they’re able to consume enough fluids to stay hydrated despite the fluid loss from bowel movements and vomiting. People who show signs of dehydration—decrease in urine, dark urine, excessive thirst and dizziness—should consult their doctor or visit urgent care.

Dr. Jackson says that age is an important factor to consider in relation to dehydration. “There is a high risk of complications at the extremes of age,” she says. “When someone is either under the age of 5 or over the age of 65, particularly with other chronic medical conditions, then we recommend they seek evaluation at urgent care if they’re showing signs of dehydration.”

Seek medical attention if your symptoms last longer than five days, or if you experience a persistent fever, severe abdominal pain when not vomiting or having diarrhea, or blood in the stool. These symptoms may indicate something more severe than food poisoning or stomach flu.

Preventing Food Poisoning and Stomach Flu

After one bout with food poisoning or stomach flu, most people are eager to avoid another. “Preventing a stomach bug involves the same steps as preventing the cold or flu,” Dr. Jackson says. “Wash your hands and be diligent about avoiding people who are showing signs of illness.”

To prevent food poisoning, wash vegetables thoroughly and take precautions when working with raw meat. Wash utensils between preparation of meat and vegetables, and don’t use the same cutting board for meat and vegetables. Meats should be cooked to an internal temperature of 165 degrees Fahrenheit, and all foods should be stored at the appropriate temperature soon after serving.

Have a question about your family’s health? Talk to a doctor. If you need a doctor, find one near you.