A stomach bug is one of the most common illnesses of childhood, and almost all of them are caused by a virus that runs its course on its own. Doctors call it acute gastroenteritis. Parents call it the stomach bug or stomach flu, though it has nothing to do with influenza. It brings some mix of vomiting, diarrhea, stomach cramps, and sometimes a fever. Almost every child gets one in the first couple of years. The illness itself is rarely the problem. The one real risk is dehydration, and nearly everything you do for a sick child is aimed at preventing it. Most children get better at home in a few days.
This guide covers what to do first, what to give your child, how to tell if they are getting dehydrated, and when to call.
What is a stomach bug?
A stomach bug is a short viral infection of the stomach and intestines. The most common causes are norovirus and rotavirus, both very contagious. Vomiting usually comes first, and watery diarrhea often follows within a day. A mild fever and loss of appetite are common. The stool is watery and frequent. It should not contain blood.
Your child usually catches it from another person or from a surface, and the first illness is often the worst. Later infections tend to be milder. Because it is viral, antibiotics do not help and there is no medicine that cures it. It has to run its course, and your job is to keep your child hydrated and comfortable while it does.
What should I do first?
Start fluids in small amounts, and give them often. This is the single most important thing you will do. Large drinks are more likely to set off more vomiting and come right back up. Small, steady amounts stay down and add up.
For a child who is vomiting, offer about a teaspoon of fluid every few minutes. It feels too slow. It is not. A teaspoon every five minutes is more than an ounce every twenty minutes, and it is far more likely to stay down than a full cup. For a baby, or an older child who will not sip from a cup, give the small amounts with an oral syringe or a spoon. Once your child has kept fluids down for a few hours, you can slowly increase the amount and space out the sips.
Do not wait for your child to look dehydrated before you start. Begin early, keep it small, and stay steady.
What should my child drink?
For most children, an oral rehydration solution is the best choice. These are sold as Pedialyte or a store brand at any pharmacy or grocery store. They have the right balance of water, sugar, and salt to replace what your child is losing, which plain drinks do not.
The drinks to avoid matter as much as the ones to choose:
- Do not use plain water as the main rehydration fluid for babies, young toddlers, or any child who may be dehydrated. Water alone does not have the salts and sugar a young child needs, and too much can lower their sodium to an unsafe level.
- Do not give soda, undiluted juice, or full-strength sports drinks. They carry too much sugar, which pulls more water into the gut and can make diarrhea worse.
Keep breastfeeding. A breastfed baby should keep nursing, often in shorter, more frequent feeds. Breastfed babies tend to handle stomach bugs better than others.
Keep formula at full strength. Once the vomiting settles, go back to your baby's usual full-strength formula. Watering it down does not help.
For an older child who refuses the electrolyte solution, a store electrolyte drink or diluted juice is a reasonable second choice, and an electrolyte ice pop often works when a cup will not. Save these for children over a year old, and keep infants on breast milk, formula, or oral rehydration solution.
What if my child throws up everything?
Expect the first few hours to be the roughest, and do not read them as failure. When a stomach bug starts, many children vomit everything for three or four hours. Then the stomach tends to settle and the vomiting eases. Vomiting from a stomach virus usually slows within twelve to twenty-four hours.
If your child throws up, stop offering fluids for thirty to sixty minutes and let the stomach rest. Then start again with an even smaller amount, a few sips at a time, and build back up slowly. Sleep helps too. A short nap often empties the stomach and calms the urge to vomit.
When your child has both vomiting and diarrhea, treat the vomiting. Focus on getting small amounts of fluid to stay down. You do not need to do anything special for the diarrhea beyond replacing fluids and returning to food when your child is ready.
When can my child eat again?
Sooner than you may think. Once your child has stopped vomiting and is asking for food, offer it. There is no need to hold food back for more than a day. Getting back to normal eating actually helps the gut heal and can shorten the illness.
Return to a normal, age-appropriate diet as your child tolerates it. Start with what appeals to them and build back to their usual meals. The old advice to give only bananas, rice, applesauce, and toast, the BRAT diet, is out of date. Those foods are fine, but on their own they are too low in protein, fat, and nutrients to help your child recover. A regular balanced diet is better.
A few practical notes. Fatty and greasy foods can worsen diarrhea, so go easy on them at first. There is no need to avoid milk or dairy unless it clearly makes the vomiting or diarrhea worse. If it does, hold it for a day or two. And expect stools to stay loose for a while even as your child improves. Loose stools during recovery are normal and do not mean things are going backward.
Do any medicines help?
For most stomach bugs, no. There is no medicine that cures a stomach virus, and the ones parents reach for often do more harm than good in children.
- Do not give over-the-counter anti-diarrhea medicine such as loperamide to a child. It is not recommended and can cause problems.
- Do not give over-the-counter anti-nausea medicine on your own. If vomiting is severe, call us. There are prescription options a doctor can consider in specific situations, but that is a decision to make together, not from the medicine aisle.
- Probiotics are not necessary. They were once thought to shorten a stomach bug, but large, careful studies found they do not help, and they are no substitute for fluids.
You can treat fever or discomfort with the usual fever medicine. When a child is vomiting a lot, not drinking, or may be dehydrated, acetaminophen is the safer choice. Avoid ibuprofen in those situations unless we advise it, and do not give ibuprofen to a baby under six months. Dose by your child's weight rather than age, use the measuring tool that comes with it, and call us if you are unsure of the right amount.
How do I know if my child is dehydrated?
Watch how your child looks and how often they urinate, not the number of times they vomit. Urine output is one of the clearest signs of whether hydration is keeping up. A child who is alert, active, and still making urine is unlikely to be seriously dehydrated, even if they have thrown up several times. That is the most reassuring sign there is.
Call us if you see the signs of dehydration:
- Less urine than usual. In an older child, no urine for more than eight hours. In a baby, no wet diaper for four to six hours. Urine that is dark yellow rather than pale.
- A dry mouth and tongue, and no tears when crying.
- In a baby, a sunken soft spot on the top of the head.
- Unusual sleepiness, fussiness, or a child who is hard to wake or too weak to stand.
The younger the child, the faster dehydration can set in, so the threshold to call is lower for babies.
How long does it last?
Most stomach bugs are short. Vomiting usually eases within twelve to twenty-four hours. Diarrhea lasts longer, commonly three to seven days, and can linger up to a week or more before stools return to normal. A stomach bug typically runs its full course in three to seven days.
Judge recovery by the whole picture, not the stool. Increasing energy, a returning appetite, and more frequent urination all tell you your child is getting better, even while the stools are still loose.
When should I call us?
Call us anytime you are worried. You never have to earn the call, and checking in early is often what keeps a long night from turning into an emergency room trip. With that as the starting point, here are the situations that should prompt a call.
Call right away, or seek emergency care, if your child:
- Is very hard to wake, unusually sleepy or confused, too weak to stand, or much less alert than usual.
- Is breathing fast, deep, or working hard to breathe.
- Shows the signs of dehydration above, especially little or no urine.
- Has blood in the stool, or vomit that is green.
- Has stomach pain that is there even when they are not vomiting, or severe pain.
- Is vomiting everything for more than about eight hours despite small, steady sips.
- Has a very high fever, or is under three months old with any fever. Do not give fever medicine to a baby this young before we have seen them.
Call us the same day if your child:
- Is under three months old and has vomited more than once.
- Is under six months old and has a stomach bug.
- Is under a year old and cannot keep the electrolyte solution down.
- Has been vomiting longer than twenty-four hours, or has had a fever for more than three days.
- Has diarrhea after recent travel, a recent course of antibiotics, or a food that made other people sick, especially with fever or blood.
- Has a weakened immune system or a significant ongoing health condition.
- Simply does not seem right to you. You know your child.
How do I keep it from spreading?
Wash hands with soap and water, and do not count on hand sanitizer. This is the part most families get wrong. Alcohol hand sanitizer works against many germs, but it does not reliably kill norovirus, the most common cause of stomach bugs. Soap and water physically wash the virus away. Sanitizer is a backup, not a substitute.
A few more things make a real difference:
- Wash hands well after using the bathroom, after changing diapers, and before handling food. Twenty seconds, every time.
- Clean and disinfect surfaces, toys, and bathrooms with a bleach-based cleaner. Let it sit for several minutes before wiping, as the label directs, since a quick spray and wipe does not kill these viruses. They survive on hard surfaces for days.
- Wash soiled clothing and bedding on the hottest setting, and wear gloves while handling it.
- Keep the sick person out of the kitchen and away from food preparation.
The rotavirus vaccine, part of the routine infant schedule, prevents one of the most severe causes of this illness and is the best protection there is for babies.
When can my child go back to school or daycare?
Wait until your child has turned the corner, not just had one good hour. Keep your child home until three things are true: no vomiting for about twenty-four hours, no fever, and diarrhea that is improving and can be contained in the toilet or a diaper. Your child should also have enough energy to take part in the day. A perfectly formed stool is not the bar. Containment and overall wellness are.
Keep your child out of swimming pools until all symptoms have fully stopped, since these viruses spread easily in water. Handwashing at home stays important for several days after your child feels well, because the virus can still be passed for a while.
The bottom line
Most stomach bugs do not need a visit. They need a plan and someone who knows your child to check in with. The plan is small, steady fluids, an early return to normal food, careful handwashing, and a close watch on how your child looks and how often they urinate. Keep those in mind and you will handle almost every stomach bug at home. What makes the difference on the hard nights is being able to reach your pediatrician early, before you are guessing alone. Because we keep our practice small, you can call and talk to a doctor who already knows your child, and we can tell you whether what you are seeing is routine or worth a closer look.
Common questions
Is the stomach flu the same as the flu? No. They are unrelated. Influenza is a respiratory illness. The stomach flu is a gut infection, usually from norovirus or rotavirus, and the flu vaccine does not protect against it.
Can I just give my baby water? No. For babies and young children, plain water lacks the salt and sugar they need and can lower their sodium to an unsafe level. Use breast milk, formula, or an oral rehydration solution instead.
Is the BRAT diet still recommended? No. Bananas, rice, applesauce, and toast are fine to offer, but they are not a complete diet and do not speed recovery. Return your child to normal, balanced meals as they tolerate them.
Should I give my child probiotics? They are not necessary. Large studies found they did not shorten the illness or improve how children felt, and they should never take the place of fluids.
What should I keep at home for stomach bugs? A few basics make the next one easier: an oral rehydration solution such as Pedialyte or a store brand, an oral syringe or medicine cup, acetaminophen, disposable gloves, paper towels, and a bleach-based cleaner.
Should I wake my child to give fluids? If your child is resting comfortably after vomiting, let them sleep. Sleep helps settle the stomach, and you do not need to wake them for sips. Start again with small amounts when they wake on their own. If your child is very hard to wake or showing signs of dehydration, that is different. Call us.
My child's diarrhea has lasted a week. Is something wrong? Usually not, if your child is drinking, urinating, and slowly perking up. Diarrhea can take a week or more to fully resolve. Call us if it lasts longer than that, gets worse, or you see blood.
Can I give anti-nausea or anti-diarrhea medicine? Not on your own. Over-the-counter anti-diarrhea medicines are not recommended for children, and anti-nausea medicine should only be used if we advise it. Call us if vomiting is severe.
My child is vomiting but has no fever and no diarrhea. Does that change anything? Often it is still a stomach bug, and the approach is the same: rest the stomach, then start small, steady sips. But vomiting on its own has other causes. Call us right away for severe or constant belly pain, green vomit, a bad headache or stiff neck, vomiting after a head injury, or a child who looks very ill. Also call for any vomiting that lasts more than a few hours in a baby, or that comes with signs of dehydration.
