Food Poisoning or Stomach Flu: Signs, Symptoms, and Causes of Each

Self
Updated ·10 min read

When you’re suddenly throwing up, dealing with diarrhea, or doing both at once, it’s only natural to wonder whether it’s because you have food poisoning or the stomach flu.

But while these two health issues are usually lumped together thanks to their intense G.I. symptoms, they’re definitely not the same thing. Also, you probably don’t want to swear off your favorite sandwich shop if it’s totally innocent in the matter. Here’s what you need to know about each—including the stomach flu symptoms and food poisoning symptoms to look out for—so you can determine what’s going on and feel better ASAP, if not sooner.

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.

What Are the Symptoms of Food Poisoning?

No matter the cause, food poisoning can cause intense symptoms. The NIDDK specifically lists these:

  1. Diarrhea or bloody diarrhea

  2. Vomiting

  3. Pain in your abdomen

  4. Fever

  5. Headache

While it’s not as common, some types of food poisoning like botulism and fish and shellfish poisoning can impact your nervous system, the NIDDK says. That can cause symptoms like:

  1. Blurred vision

  2. Headache

  3. Paralysis

  4. Tingling or numbness of your skin

  5. Weakness

Pretty scary, right?

What Are the Symptoms of Stomach Flu?

The symptoms of stomach flu usually aren’t all that different from the symptoms of food poisoning. Just like with food poisoning, the stomach flu can cause vomiting, diarrhea, nausea, abdominal pain, muscle aches or headache, and a fever, according to the Mayo Clinic.

  1. Watery, usually non-bloody diarrhea

  2. Abdominal cramps and pain

  3. Nausea, vomiting, or both

  4. Occasional muscle aches or headache

  5. A low-grade fever

How Are Food Poisoning and Stomach Flu Diagnosed?

There’s a lot of overlap between the symptoms of food poisoning and stomach flu, so you—and your doctor—may need to do a little detective work to try to suss this out.

Mostly, it comes down to the symptoms you’re dealing with.

Here are a few things to consider:

When did symptoms set in and how long are they lasting?

The stomach flu typically shows up within one to three days after you’ve been exposed, and it usually only lasts a day or two, according to the Mayo Clinic. After that, you should start to feel like yourself again, Dr. Adalja says.

If you’re dealing with symptoms for a shorter or longer time than a day or two, you may have food poisoning. While norovirus is a common cause of both food poisoning and the stomach flu, so many bacteria can potentially cause the food poisoning that it can have a wider time frame than the stomach flu. Symptoms of food poisoning can crop up just a few hours after contamination, or even days or weeks later, and they can typically last from a few hours to several days, according to the Mayo Clinic.

What kind of diarrhea situation are you dealing with?

If you have diarrhea and can stomach looking into the toilet bowl, take a peek. It’s like the poop version of reading tea leaves: If you see blood in your diarrhea, it could be a sign of food poisoning.

Bloody diarrhea is more likely to be a symptom of some types of food poisoning because some bacteria, like shigella, can cause inflammatory changes in the intestines and lead to bleeding, but viruses are less likely to do so, Dr. Adalja explains. (If you do see blood in your poop, you should let your doctor know.)

Are you projectile vomiting like that girl from The Exorcist?

Norovirus seems more likely to cause projectile vomiting and stomach cramps in patients than most other pathogens that cause food poisoning or the stomach flu. “The precise mechanism behind norovirus-induced [projectile vomiting] and stomach cramps is unknown but is likely an interaction between the virus and the immune system,” Dr. Adalja says.

Your doctor can collect a stool sample to figure out what’s happening and treat you from there, the Mayo Clinic says.

How Are Food Poisoning and Stomach Flu Treated?

Basic treatment for food poisoning and the stomach flu is the same, but if you have a severe case of either, you might need to see a doctor.

Regardless of whether you have food poisoning or the stomach flu, the most important thing is to try to keep yourself hydrated, Dr. Adalja says. The vomiting, diarrhea, and inability to eat or drink much can dehydrate you. While water is great, an electrolyte solution like Pedialyte can help replace nutrients and electrolytes you’ve lost, so it isn’t a bad option if you can handle it, Dr. Adalja says.

These illnesses typically pass with a lot of suffering but minimal complications. However, there are some signs that you need medical attention, according to the Mayo Clinic:

  1. You’ve been vomiting frequently and unable to keep liquids down for more than 24 hours

  2. You see blood in your vomit or poop

  3. You have severe abdominal pain

  4. You have diarrhea for three or more days

  5. You experience signs of dehydration like excessive thirst, dry mouth, dizziness, and dark yellow pee

  6. You have a fever

  7. You experience any neurological issues like blurry vision, muscle weakness, or tingling in your arms (campylobacter, a common cause of food poisoning, is also a risk factor for the rare autoimmune illness Guillain-Barré syndrome, which affects the neurological system by damaging nerves, the CDC says)

Depending on what you’re dealing with, treatment might range from antibiotics to anti-nausea medications to replacing lost fluids via I.V.

How Can You Prevent Food Poisoning?

Once you’re done puking, you’ll probably want to avoid the experience again. Being on top of your hygiene is the first step. That means washing your hands well, especially around food, and if you have kids, making sure they’re washing their hands well too. Here are a few other precautions you can take to prevent food poisoning, according to FoodSafety.gov:

  1. Keep raw and ready-to-eat food separate

  2. Cook foods to the recommended temperatures

  3. Refrigerate or freeze food within one to two hours of cooking or buying it

  4. Avoid thawing food at room temperature

  5. Throw out any food you’re not sure about. If you’re even a bit hesitant, research the shelf life of that food so you know when it’s no longer good. Avoid just reheating leftovers repeatedly—that doesn’t extend their shelf life (and can make the quality worse too, according to the U.S. Department of Agriculture)

How Can You Prevent Stomach Flu?

The Mayo Clinic recommends following a few key steps to prevent the stomach flu:

  1. If you’ve recently come into contact with someone who has the stomach flu or if someone in your home has it, disinfect surfaces as often as possible

  2. Avoid getting too close to someone who has the virus

  3. Avoiding sharing things like utensils, drinking glasses, plates, and towels

  4. Make sure your kids are vaccinated against rotavirus, which most typically causes the stomach flu in children (there’s unfortunately no norovirus vaccine for adults, though)

  5. When traveling, drink bottled water and avoid ice cubes (both may be contaminated) and be wary of raw food and undercooked meat and fish

  6. Finally, make sure you follow food safety recommendations, like washing your hands after you use the bathroom and before you eat

When to See a Doctor

It never hurts to check in with your doctor if you’re feeling miserable and can’t find relief. But the Mayo Clinic says you should definitely call or see your doctor if you have the following symptoms:

  1. You’re not able to keep liquids down for 24 hours

  2. You’ve been vomiting for more than two days

  3. You have diarrhea for more than three days

  4. You’re vomiting blood

  5. You have extreme pain or severe stomach cramps

  6. You’re dehydrated

  7. You notice blood in your poop

  8. You have a fever (a temperature higher than 100.4 degrees Fahrenheit)

  9. You have neurological symptoms like blurry vision, muscle weakness, and tingling in your arms

Yes, it hurts to toss out that delicious sandwich you forgot to pop in the fridge. But getting food poisoning or the stomach flu hurts a whole lot more.

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Originally Appeared on SELF