The Truth About Stomach Flu

Medically Reviewed by Melinda Ratini, MS, DO on February 16, 2024
4 min read

If your child suddenly has an attack of diarrhea and vomiting, and they complain of a stomachache, you may think to yourself, "stomach flu."

No, not really.

What's often called "stomach flu" is gastroenteritis, an infection of the stomach and intestines. The flu, or influenza, is different. It causes sore throats, runny noses, and general aches and pains. It rarely causes stomach problems.

Viral infections are the usual cause of gastroenteritis. Bacteria can sometimes bring it on.

The sickness usually passes in about 10 days without medication. The first few days tend to be the worst, but you can take steps to help your child get through it.

Stay well-hydrated. The biggest danger from gastroenteritis is dehydration. Due to the vomiting and diarrhea, your child's body loses more fluids than it takes in. So the most important thing you can do is keep your child hydrated, says Andrew Nowalk, MD, PhD. He's an assistant professor of pediatrics at Children's Hospital of Pittsburgh.

Not just any fluid will do. Water is good, but in some cases, it may not be enough. It won't replace the important electrolytes (salt, sugars, and minerals) your child's body loses when it's dehydrated.

Drinks that do replace salt and minerals are called electrolyte solutions or oral rehydration solutions. You can buy them at your local drugstore. They can even be bottle-fed to infants.

Some sports drinks promise to replace electrolytes as well. They have a lot of sugar but are OK for most school-age children and teenagers. They're not a good idea for very young children, though, says Peggy Pelish, PhD. She's an associate professor with the University of Nebraska Medical Center College of Nursing.

Keep children away from milk. It can make stomach problems worse. Doctors recommend clear fluids. If you're the parent of a young baby, talk with your doctor about breastfeeding or formula.

Drinks that have a lot of acid (orange juice) or caffeine can also cause belly problems and discomfort.

Too much of even the right kind of liquid can make vomiting worse if given too rapidly, so take it slow at first and make sure it doesn’t make the problem worse. Try 1 teaspoon every 4 to 5 minutes, Nowalk says.

Introduce food slowly. Once your child can drink liquid and keep it down, you can start adding food. But keep it bland. Try bananas, bread, rice, applesauce, and toast first. Chicken noodle soup and crackers are also good choices. Once you know those are going down OK, you can try lean meat and cooked vegetables.

Don't give your sick child foods that are fried, spicy, fatty, or have a lot of acid. They can make stomach problems worse.

Skip over-the-counter meds. With gastroenteritis, time really is the best medicine. When your child is sick, you may be tempted to give them over-the-counter medicines. As hard as it may be, don't do it. Not only will most medications not help, they may even make it worse. The vomiting and diarrhea are the body’s way to fight the infection by getting rid of everything. You don’t want to stop that process. Just make sure your child stays hydrated.

Ibuprofen can upset your child's stomach even more, and acetaminophen can cause liver problems. Antibiotics don't help against viruses (although they do against bacteria). And anti-diarrhea or anti-vomiting medicines can make the infection last longer. They can also be dangerous for very young children.

There is one exception: If your child has a fever, you can give them acetaminophen or ibuprofen to bring it down. But don't give ibuprofen to someone with an upset stomach, as it can further upset the stomach. Other than that, stick with fluids and bland foods.

Most cases of gastroenteritis go away on their own. See the doctor if the vomiting and diarrhea continue more than a few days, or if you notice any signs of dehydration like:

  • Not urinating
  • Dry mouth (no saliva)
  • Crying without tears
  • Fever over 102 F
  • Lack of energy
  • Crankiness
  • Soft spot on the top of the baby's head is sunken.
  • Blood or pus in stool or vomit, or having a dark, tarry stool

Your child may need to get checked sooner if they have other conditions, such as diabetes, that put them at higher risk for fluid loss.

Follow these easy steps:

  • Get your child vaccinated against rotavirus, which is the most common cause of gastroenteritis.
  • Wash hands often with warm soap and water, especially when you use the bathroom, change diapers, and before and after you handle food. "Good soap and water hand-washing is probably our best protection," Nowalk says.
  • Wash all fruits and vegetables before eating them. Cook eggs, fish, and meat all the way through. This may prevent gastroenteritis caused by bacteria.

If the diarrhea doesn’t go away, has blood in it, or if you and your child were recently traveling internationally to certain parts of the world, your doctor may need to run some tests and may prescribe antibiotics.