Last updated: September 2026
A stomach bug in kids usually means vomiting for 1 to 2 days and diarrhea for 3 to 7 days, and the job at home is to keep your child hydrated while it runs its course. Most children need nothing more than small, frequent sips of an oral rehydration solution and an early return to normal food. What matters most is knowing the dehydration signs that mean call us, and the red flags that mean go to the ER.
Key takeaways
- Norovirus is the most common cause. It peaks from November to April and spreads fast through daycares and schools.
- Rehydrate in small amounts: a teaspoon or syringe of oral rehydration solution every 5 minutes, starting 30 to 60 minutes after the last vomit.
- Skip the BRAT diet and skip antidiarrheal medicine. Return to a regular diet as soon as fluids stay down.
- Hand sanitizer does not kill norovirus. Wash hands with soap and clean surfaces with diluted bleach.
What causes a stomach bug in kids?
The medical name is viral gastroenteritis, and the leading culprit is norovirus. The CDC calls it the leading cause of vomiting and diarrhea in the United States, with 19 to 21 million illnesses a year and about 465,000 emergency department visits, mostly in young children. Outbreaks happen year-round but are most common from November to April. [Source: CDC, Norovirus Facts and Stats]
Rotavirus used to be the number one cause of severe diarrhea in babies. Since the vaccine arrived in 2006, hospitalizations among U.S. children under 5 have fallen by about 75 percent. [Source: AAP HealthyChildren.org, Rotavirus in Children] Because norovirus season overlaps with flu and RSV, our guide to cold versus flu symptoms can help you sort out a feverish, vomiting child.
How long does a stomach bug last in kids?
Symptoms start 12 to 48 hours after exposure. Vomiting usually comes first and is the shortest phase, typically 1 to 2 days. Diarrhea follows and can hang on for 3 to 7 days. Most children feel better within 1 to 3 days even if stools stay loose longer. [Source: CDC, About Norovirus] Rotavirus runs longer, with vomiting and watery diarrhea for 3 to 8 days.
Call us if vomiting continues past 24 hours in an infant, or if diarrhea is still heavy after a week.
How do I rehydrate a child who keeps throwing up?
The most common mistake is offering too much too fast. A full stomach comes right back up, so go small and go often.
- Wait 30 to 60 minutes after a vomit so the stomach can settle.
- Give 1 teaspoon (5 mL) of oral rehydration solution every 5 minutes. Use Pedialyte or a store-brand equivalent. A medicine syringe works well for toddlers who refuse a spoon.
- Increase slowly. After 15 to 20 minutes with no vomiting, move to 2 teaspoons every 5 minutes, then a tablespoon, then small sips from a cup.
- If your child vomits again, go back to step one.
Avoid juice, soda, and sports drinks. The AAP notes that sugary drinks can make symptoms worse, and they lack the salt balance needed to replace what is lost. [Source: AAP HealthyChildren.org, Norovirus: What to Do If Your Child Catches This Stomach Bug] For infants, do not give plain water alone. Water without electrolytes can push a baby’s sodium too low.
Breastfed babies: keep nursing, shorter and more often. The AAP says many breastfed babies stay hydrated with frequent breastfeeding alone. [Source: AAP HealthyChildren.org, Treating Dehydration with Electrolyte Solution]
Formula-fed babies: pause formula during active vomiting and use oral rehydration solution. Once fluids have stayed down for several hours, restart full-strength formula without diluting it.
What should I feed my child after a stomach bug?
The BRAT diet (bananas, rice, applesauce, toast) is no longer recommended by the AAP because it lacks nutrition and may prolong recovery. It is also not necessary to withhold food for longer than 24 hours. [Source: AAP HealthyChildren.org, Diarrhea in Children]
Once your child has kept fluids down for a few hours and wants food, offer a regular diet: rice, potatoes, bread, crackers, lean meat, yogurt, fruit, vegetables. Loose stools may pick up when food restarts. That is expected, not a reason to stop feeding, as long as your child is drinking and peeing.
Can I give my child medicine for vomiting or diarrhea?
For most kids, no. Over-the-counter antidiarrheals (loperamide, bismuth) are not recommended under age 2 and can be harmful in older children, because slowing the gut traps the virus and masks worsening symptoms. [Source: AAP HealthyChildren.org, Diarrhea in Children]
Anti-nausea medicine is different, but only by prescription. The AAP advises never using anti-nausea medicines unless your pediatrician specifically prescribes them. [Source: AAP HealthyChildren.org, Treating Vomiting] In our offices, a single dose of ondansetron (Zofran) is something we may prescribe for a child who cannot keep any fluids down, because breaking the vomiting cycle often prevents an IV in the ER. That decision needs an exam, which is why we hold same-day sick visits every day. Antibiotics do nothing for a viral stomach bug, and a low-grade fever is common (see child fever and when to worry).
What are the signs of dehydration in a child?
Dehydration is the real risk, and wet diapers are your best gauge. The AAP flags fewer than six wet diapers a day in an infant as a warning sign, and urinating only once or twice a day as severe dehydration. [Source: AAP HealthyChildren.org, Dehydration]
| Severity | What you see | Wet diapers or urine | What to do |
|---|---|---|---|
| Mild | Thirsty, slightly dry lips, less energetic but playing | Infant: 4 to 6 wet diapers a day. Older child: peeing about every 6 hours | Rehydrate at home. Call if not improving in 12 to 24 hours. |
| Moderate | Dry mouth, few or no tears, sunken eyes, fussy or sleepy, dark urine | Infant: fewer than 4 wet diapers in 24 hours. Older child: no urine for 6 to 8 hours | Call Sun Pediatrics today for a same-day visit. Keep offering sips. |
| Severe | Very sleepy or hard to wake, cool blotchy hands and feet, sunken soft spot, fast breathing | Infant: no wet diaper in 8 or more hours. Any child: urine only 1 to 2 times a day | Go to the ER or call 911. This needs IV fluids. |
For age-specific detail, read signs of dehydration in babies and signs of dehydration in toddlers. For a baseline, see how many wet diapers a newborn should have and wet diapers for a 1-year-old.
When should I take my child to the ER for a stomach bug?
Most stomach bugs never need an emergency room. Go to the ER, or call 911, for any of these:
- Green (bile) vomit, bloody vomit, or vomit that looks like coffee grounds
- Blood in the stool
- Severe belly pain, a swollen or hard belly, or pain that settles in the lower right side and worsens with movement (possible appendicitis)
- No urine for 8 or more hours in an infant, or 12 or more hours in an older child
- Lethargy: limp, hard to wake, or not responding normally
- Vomiting beyond 24 hours in an infant, or forceful vomiting after every feed in a baby under 3 months
The AAP lists these same signs as reasons to seek care immediately. [Source: AAP HealthyChildren.org, Causes of Vomiting in Infants and Children]
Short of that list, a child who is vomiting but alert, or has diarrhea and is still peeing, belongs at the pediatrician. Our post on pediatrician versus urgent care walks through the decision, and a secure video visit works well for a quick hydration check.
How long is a stomach bug contagious, and when can my child go back to school?
Norovirus is most contagious while symptoms are active, but the CDC notes people can spread it for a few days after feeling better and shed it in stool for 2 weeks or more. [Source: CDC, About Norovirus]
The AAP’s school guidance is to keep a child home if they have had vomiting or diarrhea within the past 24 hours. [Source: AAP HealthyChildren.org, When to Keep Your Child Home from School] For norovirus, the CDC and AAP say waiting 48 hours cuts spread further, and many daycares require stools to be near normal before a toddler returns. Check your center’s policy.
How do I stop a stomach bug from spreading through my house?
Wash hands with soap and water for 20 seconds. Hand sanitizer does not work well against norovirus, according to the CDC.
Clean with bleach, not wipes. The CDC recommends 5 to 25 tablespoons of household bleach per gallon of water on surfaces touched by vomit or diarrhea, left wet for at least 5 minutes. [Source: CDC, Preventing Norovirus]
Wash soiled laundry hot on the longest cycle and machine dry.
Norovirus has no vaccine yet, but rotavirus does. RotaTeq is given at 2, 4, and 6 months, Rotarix at 2 and 4 months, with all doses finished before 8 months. About 9 in 10 vaccinated babies are protected from severe rotavirus illness. [Source: CDC, Rotavirus Vaccination] We are glad to talk through questions as a vaccine-friendly pediatrician.
How Sun Pediatrics can help
A stomach bug rarely waits for a convenient time. Sun Pediatrics holds same-day sick visits every day at all four offices: Marietta, East Cobb, Alpharetta, and Cumming. We are open Monday through Thursday 8:00 to 4:45, Friday 8:00 to 4:15, and we run a Saturday clinic from 9:00 to 12:00 on the first and third Saturday of the month.
At a visit we check hydration and weight, examine the belly, and decide whether a dose of ondansetron will help. When vomiting and fever come together in flu season, we can run in-office rapid tests for flu, RSV, COVID, and strep. Secure video visits are also available.
Every physician is board certified, and our team cares for children from birth through 18. Request an appointment online or call 678-501-5601. Same-day sick visits are held every day at all four offices.
Frequently asked questions
Can my child have Pedialyte instead of water?
Yes, and for infants and toddlers with active vomiting it is the better choice. Oral rehydration solution replaces lost salt and sugar in the right balance. Plain water is fine for older kids once fluids are staying down.
Is Gatorade okay for a stomach bug?
Sports drinks have too much sugar and too little sodium for a child with diarrhea, and the AAP advises against them. Use an oral rehydration solution, diluted juice, or broth instead.
Should I stop breastfeeding while my baby has a stomach bug?
No. Keep nursing, shorter and more often. Breast milk provides fluid, electrolytes, and antibodies. Add electrolyte solution only if we advise it.
Can my child go to daycare 24 hours after the last vomit?
Twenty-four hours symptom free is the minimum most schools follow. The CDC and AAP say 48 hours cuts spread further, and many daycares also require diarrhea to be back to normal. Check your center’s rules.
This article is for general information and is not medical advice. Contact your pediatrician for care specific to your child.
