Six Signs You May Have Food Poisoning

Some symptoms can be misleading, but if you find yourself checking off each telltale sign on this list, you may be dealing with foodborne illness.

woman experiencing stomach cramps and severe pain
Photo: Kolapatha Saengbanchong / EyeEm & Getty Images

While it's a relatively common problem, food poisoning doesn't always come with the same symptoms. Most healthcare professionals will tell you that there's a variety of potential symptoms based on different foodborne bacteria. Those particularly at risk, including the young, elderly, or those with underdeveloped immune systems, could experience wildly different symptoms. Even defining food poisoning can be a bit tricky, since the term is often used interchangeably with "stomach flu" or a "bug." Here we're highlighting everything you need to know about food poisoning, including how you contract it, symptoms to watch out for, and recovery tips.

What Causes Food Poisoning?

The reason that so many of us have experienced food poisoning is because there are so few ways to tell if food will make you sick. Usually, cases begin after you've eaten something that's undercooked, a dish that's been left out for just a bit too long, or a meal that was prepared in an unhygienic manner. The Centers for Disease Control and Prevention correlates what most people know as food poisoning to a condition called gastroenteritis, which is defined as an irritation of the stomach-in most cases, it's caused by salmonella bacteria, E. coli, or norovirus. You might assume you've come down with food poisoning because you ate something that was tainted in one way or another, but CDC experts say that you can contract gastroenteritis just by touching someone who has a case of it or by not washing your hands after using the bathroom. This is why people associate food poisoning with "stomach flu," but gastroenteritis is not considered influenza.

While foodborne bacteria is usually the culprit behind food poisoning, there are many different forms of bacteria that can produce different symptoms. Salmonella is the most prevalent form of food poisoning in America, and, according to professionals at the Mayo Clinic, can lead to symptoms that are most commonly associated with food poisoning. Each case is different, but the following symptoms are general and likely will manifest themselves in most any form of food poisoning, regardless of bacteria.

Nausea and Vomiting

Vomiting can be caused by bacteria from salmonella to listeria and E. coli, among others, and is one of the most common signs of food poisoning. Some bacteria can cause vomiting and other symptoms within 12 hours-but according to guidance published by Harvard Medical School, listeria bacteria could produce symptoms like severe nausea and vomiting anywhere from three to 70 days after first exposure.


This is another common symptom that can lead people to misdiagnose themselves, as diarrhea can occur normally if your stomach or digestive tract has become irritated in some way. But healthcare professionals report that E. coli and campylobacter (a form of bacteria that's most likely consumed in contaminated water) can cause blood to appear in your stools, which is a telling sign that you are experiencing food poisoning and should see a physician.

Abdominal Pain and Cramps

Even if you aren't running for a bathroom, you may still experience intense abdominal pain and cramps. Experts say this symptom alone may not be a true indicator that you've come into contact with foodborne bacteria on its own, but more so if you're experiencing this with other symptoms on this list.


Gas is another unfortunate side effect of food poisoning, and it's often one of the longer lasting symptoms. The CDC reports that bloating can be an issue for up to a week, and is particularly the case with cyclosporiasis, a bacteria that's found in feces and can contaminate both food and water upon contact.

Low Fever

You may mistake an elevated fever for a cold, but it could be a signal that your intestinal tract has come into contact with certain foodborne bacteria or norovirus. The CDC reports that in the case of listeria poisoning, for example, you could contract a fever that lasts for at least 48 hours.

Dehydration and Headaches

Because of the harsh nature of most of these symptoms, your body is likely to lose water over the course of the infection. You'll need to up how much water you're drinking, and focus on proper hydration even in the weeks after overcoming these symptoms. Dehydration can often cause headaches as another side effect, but you should be concerned about a chronic headache if it's accompanied by the other symptoms on this list.

The Best Methods for Recovering from Food Poisoning

You should refrain from taking over-the-counter medication for any of the symptoms above without consulting a doctor first, the experts at the CDC and Harvard Medical School say. One of the best things to do is to keep yourself properly hydrated: Dr. Olveen Carrasquillo, M.D., M.P.H, a professor at the University of Miami Miller School of Medicine, says that you can add electrolyte-rich fluids (such as sports drinks) to your routine to help your body rehydrate.

The "BRAT" diet-a common meal plan centered around bananas, rice, applesauce, and toast employed by healthcare professionals to help patients keep solid foods down-is a solid approach to reintroduce meals into routine. But in the weeks after your initial sickness, try to rebuild the strength of your digestive system with powerhouse staples like leafy green vegetables, whole grains, and lean proteins, staying away from over-processed foods that could irritate your digestive tract once more. Most medical professionals will tell you that the majority of bouts of food poisoning will resolve themselves after a few days of symptoms. There's not much you can do to beat the system here: Be sure to rest, drink plenty of fluids, and slowly return to a full-balanced diet in the weeks after you've overcome whichever symptoms plague you the most.

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