What Is Food Poisoning?
Food poisoning is an infection or irritation of your digestive tract that you get from having infected food and drinks, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). It’s usually acute (meaning it comes on hard and fast), and most people get better on their own without treatment, the NIDDK says.
Having food poisoning (also known as foodborne illness) means your body is rebelling against viruses, bacteria, or other harmful substances in something you ate, Benjamin Chapman, Ph.D., an assistant professor and food-safety extension specialist at North Carolina State University, tells SELF. These pathogens can lurk in a wide variety of foods. You may also come down with food poisoning after reheating old food and drinking or eating something that has expired (especially dairy).
Food poisoning isn’t a rare thing—about 48 million people in the U.S. have food poisoning each year, the NIDDK says.
What Is the Stomach Flu?
First, it’s important to know that the stomach flu has no relation to the “regular” flu, a.k.a. influenza. Influenza is a highly contagious viral infection that causes fever, muscle aches, fatigue, and respiratory issues. In severe cases, influenza can be life-threatening (seriously, get your flu shot every year).
The stomach flu, on the other hand, is what’s known as viral gastroenteritis, and it happens when a virus causes an infection in your gut, according to the U.S. National Library of Medicine.
What Causes Food Poisoning?
When it comes to viruses, norovirus is the most common cause of foodborne illness in the U.S., the Centers for Disease Control and Prevention (CDC) says. It typically hangs out in items like raw, ready-to-eat produce; shellfish; and contaminated water.
On the bacterial side, you have salmonella, listeria, shigella, campylobacter, E. coli, and more that can make you sick, according to the Mayo Clinic. These can show up in anything from hot dogs, milk, egg yolks, alfalfa sprouts, meat, poultry, and beyond.
Food contamination can happen at any point, whether it’s through soil as it’s grown, in a storage facility, or on your countertop when you leave food out for too long, the CDC says. You may also get food poisoning if someone with one of these illness-causing microorganisms in their system handles your food or utensils.
What Causes the Stomach Flu?
Norovirus—which you just read about—is also one of the most common causes of the stomach flu, leading to between 19 and 21 million viral gastroenteritis infections each year, per the CDC. So yes, the stomach flu can be a type of food poisoning.
You can pick up viruses that cause the stomach flu by touching a surface that someone with the infection touched or having direct contact with them. You can also get it through food, though, which brings us to the trippiest part of this entire conversation…
You can technically have food poisoning and the stomach flu at the same time. Let’s say you pick up a case of viral gastroenteritis after a dinner of norovirus-contaminated scallops. That basically means you got the stomach flu from a food-based source. “Is it food poisoning or the stomach flu? There’s not really a clear line you can draw,” Amesh A. Adalja, M.D., a board-certified infectious disease physician and senior scholar at the Johns Hopkins Center for Health Security, tells SELF.