The parent’s guide to stomach bugs

Endless coughs and sneezes, runny noses, and unexplained itchy bumps—kids seem to be a magnet for germs. In our parent’s guide to childhood illnesses, we talk about the symptoms and treatments for the most common conditions. Read the full series here. 

What is a stomach bug? | Symptoms | Diagnosis | Treatments | Prevention 

Every parent knows that look—the look a kid gets right before throwing up. If you are lucky, you’ll have a moment to grab something to contain the yuck. If not, you’ll be doing laundry that night for sure (and maybe some carpet cleaning). Stomach bugs in children are gross, but they are common and usually kids recover quickly and fully.

What is a stomach bug?

Although it is frequently called the stomach flu, stomach bugs have nothing to do with the seasonal influenza virus (aka the flu), which is a respiratory illness. Stomach bugs are usually viral illnesses that may affect both the stomach and the intestines.

“A stomach bug is a gastroenteritis, which means inflammation of the stomach or intestine, says Aymin Delgado-Borrego, MD, a triple-board certified doctor in pediatrics, pediatric gastroenterology and pediatric hepatology at KIDZ Medical Services in Florida. “This inflammation can be the result of either a viral or bacterial infection.”

Gastroenteritis is common. It is responsible for approximately 1.5 million office visits, and 200,000 hospitalizations each year in the United States.

While 90% of children in the United States will have a mild case that does not require medical treatment, there are risks of complications, particularly of dehydration. Approximately 300 children die each year of gastroenteritis in the United States. This number is higher in developing countries, particularly where sanitation and access to clean water and medical care are limited.

What causes stomach bugs?

The causes of gastroenteritis fall into three main categories: viral, bacterial, or parasitic.

1. Viral

Viral infections are the most common cause of gastroenteritis in American children and are commonly spread in daycare, classrooms, cruise ships, and other crowded environments. These infections are typically caused by one of the following viruses:

• Norovirus
• Adenoviruses
• Enteroviruses (during summer months)
• Astroviruses
• Rotaviruses

2. Bacterial

Bacterial gastroenteritis is a less common cause of stomach bugs in children and is usually the result of food poisoning from improperly cooked or stored foods.

Certain types of aggressive bacteria—such as Campylobacter, Salmonella, or E. coli—can cause severe food poisoning and gastrointestinal symptoms in children.

3. Parasitic

Also less commonly, intestinal parasites can cause gastrointestinal distress in children. Among American children, giardia lamblia (the parasite that causes giardiasis), is the most common parasitic cause of diarrhea.

Intestinal parasites can be spread on dirty hands, contaminated surfaces (like toys and bathroom fixtures), and in contaminated water or food. Infections caused by giardia lamblia are more common for children in daycare and those who go camping

Are stomach bugs contagious?

Gastroenteritis is quite contagious. It is spread through contact with body fluids (especially stool and vomit) that contain viral particles, bacteria, or parasites.

This contact is not always as obvious as changing diapers or cleaning up vomit. These particles can transfer by touching surfaces with unwashed hands, sharing food or utensils, and other unhygienic practices.

How long are stomach bugs contagious?

“The question of how long [stomach bugs are contagious] depends on the underlying organism, whether virus or bacteria,” Dr. Delgado-Borrego says. “As a rule of thumb, a child is contagious as long as they’re having diarrhea. Stomach bugs last a few days up to a couple of weeks.”

The cessation of diarrhea is a common marker for when a stomach bug is no longer considered contagious. “While vomiting won’t last longer than 18 to 24 hours, diarrhea in infants and toddlers who have a stomach bug can sometimes last seven to 14 days,” says Rashmi Jain, MD, pediatrician and founder of BabiesMD in California. “During this entire time, they can still be shedding viral particles in their stools and be contagious. As pediatricians, we caution that children can be contagious until diarrhea has been resolved for a good 24 to 48 hours.”

Children should be kept home from school or daycare and away from other people during this time.

Stomach bug symptoms in children

Common symptoms of a stomach virus in children include:

• Vomiting
• Mild diarrhea
• Abdominal pain or cramping
• Lack of or reduced appetite
• Irritability
• Fussiness in babies and toddlers
• Low-grade fever (sometimes)
• Headache (occasionally)

Commonly, viral gastroenteritis starts with vomiting and then may evolve to watery (or explosive) diarrhea within 12 to 24 hours. Viral gastroenteritis is usually self-limited and does not involve blood in the vomit or stool.

Bacterial gastroenteritis is less common, but more serious than viral gastroenteritis. Symptoms can include:

• Nausea
• Vomiting
• Diarrhea
• Fever
• Chills
• Abdominal pain or cramping
• Bloody stools
• Headache

Bacterial gastroenteritis presents with rapid vomiting and diarrhea within hours of eating contaminated food. Some bacterial infections result in bloody diarrhea.

Children with the most common parasitic gastrointestinal infection, giardiasis, may show the following symptoms:

• Severe diarrhea (This is usually the first symptom. The diarrhea often floats, is shiny, and smells very bad)
• Abdominal cramps
• Lots of intestinal gas that causes enlarged belly
• Low energy
• Loss of appetite
• Nausea
• Vomiting
• Low-grade fever
• Weight loss

Symptoms may last for five to seven days or longer. Giardiasis can be acute (short-term) or it can become chronic (long-term). It’s possible for children to show no symptoms initially. Parasitic infections usually occur seven to 14 days after exposure and have long-lasting symptoms (up to six weeks) without treatment. Vomiting is rare with parasitic infections.

What should I do if my child has a stomach bug?

Most of the time gastroenteritis does not require a visit to the pediatrician. If your child can take in and keep down fluids, you can manage it at home. The biggest cause for concern with viral gastroenteritis is the risk of dehydration, especially in babies and young children.

“The problem that arises with stomach bugs is that oftentimes, especially in infants and toddlers, children will lose more of their body’s fluid in the process of vomiting and diarrhea than they can drink and absorb to replenish,” says Dr. Jain. “Thus, they are at high risk for dehydration.”

Dr. Jain recommends parents see a healthcare provider if their child shows signs of dehydration, such as:

• Dry lips or tongue
• Absence of saliva in their mouth
• No tears when crying
• Decreased urination
• Fatigue, lethargy, or excessive sleepiness
• Inconsolable irritability
• A sunken fontanel (soft spot) on the top of a young infant’s head
• Pale or sickly appearance 

You should also seek medical care if your child meets any of the following criteria:

• Is younger than 2 months old
• Has a high fever greater than 102 degrees Fahrenheit
• Shows blood or pus in stools or vomit, or has dark forest green colored vomit
• Has severe abdominal pain or swollen abdomen
• Has yellowish skin or whites of the eyes
• Stops vomiting for a few hours but then starts again
• Vomits for longer than 18 to 24 hours
• Has diarrhea that persists more than 72 hours
• Has a chronic medical condition
• Is unable to keep necessary medication down

If you recently took your child on a trip to a foreign country, that may also signal a need for medical care. If symptoms are mild, a child can see their pediatrician or primary care provider. If symptoms are more severe, especially in terms of dehydration, take your child to the emergency room. Call 911 if the child has:

• Trouble breathing
• Confusion
• Extreme drowsiness or loss of consciousness
• Trouble walking
• Rapid heart rate
• Stiff neck
• Seizure

Bacterial GI infections can typically resolve on their own. You should seek medical care if the child has bloody stool or is unable to keep anything down. Parasitic gastroenteritis requires medical care to help your child recover. The healthcare provider will likely ask for specifics about the symptom duration and for a description of the vomit and/or stool. Gastroenteritis is usually diagnosed by examination of symptoms and rarely requires further testing, unless there are unusually severe symptoms or bacterial or parasitic gastroenteritis is suspected.

Treatments for a stomach bug in children

There is no medical cure for viral gastroenteritis. It will go away on its own, usually within a few days to a week (though diarrhea may last longer than a week). Treatment is aimed at symptom management.

Dietary remedies

“The most important part of managing a stomach bug is to keep your child hydrated,” says Dr. Jain. “This usually means waiting for them to stop vomiting and offering very small amounts (10–15 ml in infants and no more than 30 ml in toddlers) of water or Pedialyte at frequent intervals (every 15–30 minutes) so that the stomach does not feel overloaded or overwhelmed as it attempts to keep the body hydrated.” 

Most parents can successfully hydrate their child at home with a teaspoon or syringe and the best liquid is an oral rehydration solution (ORS),which you can make or purchase in packets at the pharmacy. Pedialyte is an acceptable alternative. Parents should not use sports drinks (such as gatorade), soda, juice, tea, or bullion solutions as these can make the problem worse and be dangerous. 

Infants and toddlers who are breastfeeding should resume doing so as soon as possible. In fact, breast milk is the best thing to give a child in these circumstances. For formula-fed infants, they can resume formula once they tolerate water, ORS, or Pedialyte without vomiting for two hours. If children become dehydrated or cannot take in or keep down liquids, they may need fluids administered by IV, usually in a hospital setting.

Once toddlers and older children are able to tolerate fluids without vomiting for at least two hours, you can start offering small bites of food. Dr. Jain recommends starting with bland, starchy foods such as crackers, toast, rice, noodles, mashed potatoes, bananas, or applesauce.

Dr. Jain advises avoiding fried fatty foods, concentrated sweets (like fruit juices, cookies, and candies), spicy foods, highly processed foods, and dairy products until the child’s stomach is settled.

Prescription medications

Bacterial gastroenteritis may be treated with antibiotics, but most bacterial infections can resolve without treatment. Antibiotics will not work for viral gastroenteritis.

Parasitic gastroenteritis is treated with a medicine (usually in liquid form) that kills the parasites. Treatment typically lasts about five to seven days. These medications may have side effects. It’s important to follow the directions given by your child’s healthcare provider.

Over-the-counter medications

Do not give over-the-counter anti-diarrhea or anti-nausea/antiemetic medications to your child without first checking with a healthcare provider. In most cases, these medications are not recommended.

If your child has a fever, Tylenol (acetaminophen) or Advil/Motrin (ibuprofen) can be used as directed. If your child vomits after taking this medication, don’t give a second dose, contact your child’s healthcare provider or pharmacist for direction.

Occasionally, the prescription antiemetic ondansetron is given with the advice of a healthcare professional, usually in cases of or risk of dehydration.

RELATED: Children’s Motrin dosage, forms, and strengths

How to prevent stomach bugs in kids

Good hygiene is the best way to prevent the spread of gastroenteritis. “The key to preventing any viral illness is handwashing and disinfection,” says Dr. Jain. This is especially important when parents, teachers, daycare workers, and babysitters are taking care of children who are dealing with a stomach bug. These viruses are extremely tenacious and can live on surfaces for days.” Ways to help prevent all forms of gastroenteritis include:

• Wash hands with soap and water frequently 
• Help children wash hands thoroughly and frequently with soap and water
• Practice food safety when preparing raw meat and refrigerating cooked foods
• Follow instructions regarding safe storage of bottles with breast milk or formula
• Use caution when traveling with regards to drinking water, raw produce, and swimming
• Sanitize toys, soiled surfaces and clothing appropriately with diluted bleach solution when necessary
• Watch for parasite infection in pets
• Prevent children from sharing food, utensils, or other personal items
• Keep sick children out of school or daycare until they are no longer contagious

If your child attends school or daycare, inform them promptly that your child has gastroenteritis so they can take proper sanitation measures.

Vaccinations

A vaccine for rotavirus is routinely given to infants and has markedly reduced the incidences of (and complications from) gastroenteritis caused by rotavirus in children. Currently, a vaccine for norovirus is undergoing trials, with promising preliminary results.

While stomach bugs are inconvenient, gross, and uncomfortable for everyone, the good news is that most stomach bugs are caused by common viruses and go away on their own with rest, fluids, and a lot of TLC.