COVID-19 and the stomach flu can both present with gastrointestinal symptoms like nausea, vomiting, and diarrhea. Here's how to tell the difference between them, according to experts.
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Young boy with stomach ache.
Credit: Roman Yanushevsky/Shutterstock

Your child looks exhausted and starts complaining of abdominal pain. Or maybe they're feeling nauseous and request the dreaded barf bucket. You might've previously written off these symptoms as a stomach bug, but these days, you're apt to wonder: Do they actually have COVID-19? After all, the coronavirus sometimes presents with gastrointestinal (GI) issues like nausea, vomiting, and diarrhea, according to the Centers for Disease Control of Prevention (CDC).

Here, experts share how to tell the difference between the stomach flu and COVID. Their advice can help you determine the best course of testing and treatment for your child's tummy trouble.

Symptoms of the Stomach Flu

First, it's important to understand the stomach flu isn't really influenza at all. According to the National Library of Medicine, it's another name for "gastroenteritis," which means an inflammation of the lining of the digestive tract.

Gastroenteritis can be caused by several different pathogens, including viruses (most commonly norovirus), bacteria, and parasites. It usually spreads by drinking contaminated water, eating contaminated food (food poisoning), or making contact with an infected person or their fecal matter.

Whatever the cause, the main symptoms of the stomach flu include tummy pain, nausea, vomiting, diarrhea, and headaches—and yes, most of those same symptoms can resemble the coronavirus. That's why so many parents feel confused about whether their child has a stomach flu or COVID-19.

Gastrointestinal Symptoms of COVID-19

COVID-19 has a long list of potential symptoms, such as sore throat, fever, congestion, headache, and fatigue. A December 2021 study published in JAMA found that a little over one-third of kids with COVID-19 also experienced gastrointestinal symptoms. These can include diarrhea, nausea, vomiting, and abdominal pain, says Jonathan Maynard, M.D., a pediatrician with Providence Mission Hospital in Southern California.

What's more, some children with COVID-19 only have GI symptoms, adds José Mayorga, M.D., Executive Director of UCI Health Family Health Center. He has seen this among his patients and his own children. "It actually happened in my own family," he shares. "One of my daughter's had the classic upper respiratory infection, the other one had stomach issues. They both tested positive for COVID."

Telling the Difference Between Stomach Flu and COVID-19

Don't know how to distinguish between COVID-19 and the stomach flu? We rounded up some clues that might help you figure out what you're dealing with.

COVID-19 often causes more extensive symptoms. In general, COVID-19 attacks more bodily systems than a typical pathogen that causes the stomach flu, says Dr. Maynard. "While there can be a few similarities between the symptoms of COVID-19 and the stomach flu, the symptoms of COVID-19 are generally more extensive," he says. In kids, COVID may lead to flu-like symptoms such as fatigue and joint pain, along with respiratory and GI issues, Dr. Maynard explains. On the other hand, kids with the stomach flu usually only experience GI symptoms (though muscle aches, headache, and low-grade fever can also occur.)

The stomach flu may create food aversions or loss of appetite, while COVID-19 can alter taste. With COVID-19, "your child's appetite may stay the same; however, they might report not tasting their food or milk or juice, reporting their food or drink 'tastes funny,' or stating 'I don't like this drink,'" says Bayo Curry-Winchell, M.D., Regional Clinical Director of Carbon Health and Urgent Care Medical Director of Saint Mary's Hospital.

Fever is more common with COVID-19. Another way to distinguish between COVID and a stomach flu is the presence of fever, says Molly O'Shea, M.D., a pediatrician who has recently served as a guest faculty for the HHS COVID Preparedness ECHO lecture series. "Many stomach viruses cause vomiting and diarrhea and few cause fever too, but COVID is much more apt to cause fever than others," Dr. O'Shea explains.

The stomach flu rarely presents with respiratory symptoms. If your child is vomiting or having diarrhea, but is also congested or coughing, COVID-19 is a more likely cause, says Dr. O'Shea. (But also note that your child could have another illness with those symptoms too, such as influenza, Dr. O'Shea reminds. Strep throat is also a possibility, as it can cause sore throat and vomiting.)

Diarrhea might come first with COVID. With COVID-19, diarrhea often comes before respiratory symptoms—so if your child has diarrhea, monitor them for new signs of illness over the next few days.

Should Your Kid Get Tested for COVID-19?

Because there's so much overlap between symptoms, it's hard to know if your child has COVID-19 or a stomach virus just by observing them. "It's important to remember that the only way to truly confirm whether it's COVID-19 or the stomach flu is to take a COVID test," says Dr. Maynard.

That said, not every instance of vomiting or diarrhea means that you have to rush out to get tested. Consider when symptoms started and whether you can trace them to something your child ate, says Dr. Curry-Winchell. For example, if your family all enjoyed a meal together, then began feeling ill with GI symptoms a few hours later, you might be dealing with a stomach flu, says Dr. Curry-Winchell. But if your child is displaying GI symptoms and you can't trace the cause, it's smart to take a COVID-19 test.

Dr. Mayorga adds that, because COVID-19 in children can sometimes present with GI symptoms alone, it's usually best to get tested if you're unsure. This is especially true during COVID-19 surges. "When there is a high circulation of COVID, you have to err on the side that this can potentially be COVID, and the best way to figure that out is getting tested," Dr Mayorga suggests.

How To Treat GI Symptoms in Kids

Whatever pathogen is causing your child's gastrointestinal symptoms, keep a watchful eye on them and make sure they stay hydrated. "Hydration is the most important thing, especially in little ones," says Dr. Mayorga. "Children, especially infants, are at high risk of getting dehydrated quickly."

Even small sips of water help when your child can't keep anything down, says Dr. Maynard. You can also offer liquids with electrolytes, like Pedialyte or a store-brand electrolyte drink. An indicator that your child is getting enough fluids is they're able to urinate a few times a day, says Dr. Maynard.

Other ways to handle GI symptoms include getting plenty of rest, eating small amounts of bland food (once vomiting subsides), and taking over-the-counter pain medication to relieve any discomfort (such as fever).

You shouldn't hesitate to call your child's pediatrician if you're concerned they've become dehydrated, or if they're showing other concerning symptoms, such as severe diarrhea that lasts for several days, blood in the stool, or a high fever. Dr. O'Shea adds that intense stomach pain that lasts more than two hours, makes your child double over in pain, or is located in the right lower area of the abdomen warrants a call to the doctor as well.

If you aren't sure whether to contact your health care provider, go with your gut. It's always better to be safe than sorry.