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Stomach Flu vs. Food Poisoning: What's Upsetting Your Stomach?

Whether it's an outbreak in your family or in the food supply, follow these tips to find the cause and the cure.

An upset stomach isn’t fun for anyone. When your tummy turns and empties its contents, it’s even worse. Between hurried trips to the bathroom, you start to wonder what you’re dealing with.

Was it something I ate? Something I touched? Someone I was with?

Is anyone else spending this much quality time with the toilet?

Man holding his stomachYour tummy troubles may come and go without you finding a clear answer. But figuring out what brought on your symptoms can help you prevent your family and friends from suffering the same fate and help you avoid stomach issues again in the future.

Symptoms of food poisoning and the stomach flu are strikingly similar.

It’s common to confuse the two. The signs are nearly identical. You start to feel nauseous. Maybe you feel feverish. Your stomach hurts and cramps until you rush to the bathroom with a bout of vomiting, diarrhea or both.

In the aftermath, you initially feel better. But the pain, cramps, vomiting and diarrhea return again and again. You’re left dehydrated and weak. You don’t even have the appetite to help get back some strength and fear that anything you eat will only continue the cycle of stomach issues.

There’s one telling difference between the stomach flu and food poisoning — the onset of symptoms. Food poisoning comes fast. It can come as quickly as a couple hours after eating contaminated food.

The stomach flu takes a little more time to develop. The warning signs typically show up a day or two after you’ve been exposed to the virus. In some cases, it can happen in as little as 12 hours. 

Woman With Stomach Pain

Get Through Your Stomach Symptoms

When your issues last more than two days, visit your primary care provider.

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While both food poisoning and the stomach flu usually pass after a couple of days, a stomach virus can linger and stick with you for up to 10 days. 

The sources of both stomach problems overlap too.

Similar to influenza, the stomach flu is caused by a virus. Instead of infecting your respiratory system, it infects your stomach. Despite its common name, the medical term is actually viral gastroenteritis.

Influenza is not even the strain of virus behind the stomach flu. There are a number of other viruses that can cause it but, more often than not, viral gastroenteritis comes from one of two viral diseases.

A common misconception is that the ‘stomach flu’ is caused by influenza or that the flu shot will help. Although you can get vomiting and diarrhea with influenza, it generally is not a GI-related illness. The cause of gastroenteritis is usually viral, with norovirus and rotavirus being the most common.


The most common cause of the stomach flu, norovirus is a highly contagious disease. It only takes a few particles of the virus to make you sick. And those that are carrying norovirus have billions of infectious particles in them. You can get norovirus from contaminated food as well as contact with infected people and surfaces.


Another virus that causes inflammation of the stomach, rotavirus is the most common cause of viral gastroenteritis in infants and children — especially during winter and spring. It primarily spreads through people and the things they touch. Even though there’s a vaccine for rotavirus, you can still get infected with rotavirus more than once.

Norovirus and rotavirus can spread through food, which further blurs the lines between food poisoning and the stomach flu. If an infected person handles the food or the particles from their vomit or poop manages to get on food, you get sick.

There are more than 250 other infections that can cause foodborne illness.

A lot of things can contaminate your food and give you food poisoning. It might be a virus, bacteria, parasite, toxin or chemical. Showing its contagiousness, norovirus is also the No. 1 cause of foodborne illness, according to the Centers for Disease Control and Prevention. It causes 58 percent of the 48 million cases of food poisoning in the United States each year.

Of the 250-plus other foodborne diseases, there are four that are primarily behind the remaining cases.


One of the most well-known sources of food poisoning, Salmonella infects more than a million people every year. And that’s a low estimate. For every person that goes to the doctor with food poisoning from Salmonella, 30 people don’t.

Salmonella is a bacteria found in a number of foods — especially eggs and raw or undercooked meat. You’re more likely to be infected by Salmonella in the summer. The warmer weather provides ideal conditions for the bacteria to grow. Summer is also grilling season in Iowa, which increases the likelihood you’ll eat undercooked pork, chicken or beef.


Campylobacter isn’t as well known as Salmonella, but it causes more reported foodborne illnesses. It’s also a bacteria that thrives in the warm summer climate. While it can infect both humans and animals, cows, chickens and turkey often carry Campylobacter without showing any symptoms. So if you eat undercooked poultry or handle it raw or drink raw milk, you may be infected with Campylobacter.

Clostridium perfringens

Clostridium perfringens is yet another bacteria found in raw meat and poultry that leads to a million more cases of food poisoning every year. It produces a toxin inside your intestines that causes cramps and diarrhea. So there’s no vomiting or fever with this infection.

This foodborne germ is more likely to be found in slow cookers or warmers, where large quantities of meat or gravy are kept warm for extended periods of time — just not warm enough. Food needs to be kept at a temperature of 140°F or higher to keep bacteria at bay. So keep an eye on the temperature and the amount of time food sits out at your next potluck.

Staphylococcus aureus

You’ve heard of Staph infections of the skin, or maybe a wound if you know somebody who had complications after surgery. Many people actually have Staph bacteria on their skin or in their nose all the time. Carriers of Staph don’t get sick but can contaminate uncooked foods like deli meat, sandwiches or pastries.

Staph food poisoning happens more suddenly than other types — as soon as 30 minutes after ingesting something infected by it. And it’s gone as quickly as it comes on. Most cases of Staph food poisoning are over within a day.

Staph, Salmonella, Campylobacter, Clostridium perfringens aren’t the only common threats. You hear of outbreaks of E. Coli, Listeria and other foodborne germs every year, forcing recalls of everything from vegetables to packaged foods. You can prevent them as well as the bugs that cause viral gastroenteritis with a few simple tips:

  • Wash your hands.
  • Wash your food.
  • Clean surfaces exposed to viruses and foods thoroughly.
  • Cook your food to the correct temperature.
  • Promptly refrigerate leftovers and reheat them properly before eating.

Call your doctor if your symptoms don’t go away.

Many cases of foodborne illness and the stomach flu pass without the need for medical attention. Because you’re unable to keep the contents of your stomach inside, the biggest concern is dehydration. Drink plenty of fluids (think, Pedialyte, Gatorade, Powerade and water) to prevent it.

When you feel like eating again, stick to simple, unseasoned foods that won’t upset your stomach, like the BRAT diet — bread, rice, applesauce and toast.

Keep your diet as bland as possible and avoid irritants to the stomach such as spicy foods, alcohol, tobacco, sweets and fried foods.

While many people recover quickly without medical assistance, you should not try to go it alone if your symptoms persist. The stomach flu and foodborne illnesses hospitalize millions of people every year. A fever above 104, dehydration, blood in your vomit or stool and prolonged vomiting or diarrhea point to a more severe case.

Both of these illnesses generally go away within a couple days. If symptoms persist longer, you need to be seen. Signs of severe illness and dehydration symptoms such as lethargy, mental status change, lack of urinary output — those are reasons you need to get seen sooner.

So if you aren’t showing signs of improvement after 48 hours, schedule an appointment with your primary care provider or visit Urgent Care<. Your doctor can perform a blood test to check for foodborne bacteria, prescribe the appropriate medications to fight the infection, rule out other common causes like stress or guide you to the self-care measures needed to recover from your stomach troubles.

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