Gastroenteritis (Stomach Flu) in Babies and Children
Content reviewed against published AAP, CDC, WHO guidelines
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Gastroenteritis is an inflammation of the stomach and intestines, commonly called the "stomach flu" (though unrelated to influenza). It causes vomiting, diarrhea, and abdominal pain. In infants and young children, the primary concern is dehydration. Most cases are viral (norovirus and rotavirus being the most common causes), though bacterial and parasitic causes also occur.
Key takeaways
- Gastroenteritis is an inflammation of the stomach and intestines, commonly called the "stomach flu" (though unrelated to influenza).
- Duration: Vomiting typically resolves in 1-2 days. Diarrhea usually lasts 3-7 days but may persist for up to 2 weeks. Full recovery including appetite return takes about 1 week.
- Go to ER if: Signs of severe dehydration — sunken eyes, no tears, lethargic, dry mouth, no wet diaper for 6+ hours
- A vaccine or immunization is available
Symptoms
How It Presents by Age
0-6 months
Highest risk for dehydration due to small body size and inability to communicate thirst. May present primarily with watery stools, decreased feeding, and lethargy. Vomiting may cause aspiration risk. Breastfed infants may have some protection.
Risk level: High — dehydration can develop rapidly
6-12 months
Frequent watery diarrhea and vomiting. Monitor closely for signs of dehydration — fewer wet diapers, dry mouth, sunken fontanelle, no tears. May refuse solids but should continue breast milk or formula.
Risk level: Moderate to high
1-3 years
Classic presentation with vomiting followed by diarrhea. Child may be clingy and irritable. Dehydration risk remains significant. Oral rehydration therapy is the cornerstone of management.
Risk level: Moderate
3-5 years
Can usually tolerate oral rehydration. Abdominal cramps and vomiting are prominent. May complain of tummy ache. Lower risk of severe dehydration but still requires monitoring.
Risk level: Low to moderate
Treatment
Oral rehydration therapy (ORT)
Small, frequent sips of oral rehydration solution (Pedialyte) — 1-2 teaspoons every 1-2 minutes. This is the WHO-recommended first-line treatment for dehydration. Do not use juice, soda, or sports drinks.
Continue feeding
Continue breastfeeding or formula feeding throughout illness. Resume age-appropriate diet as soon as tolerated — the BRAT diet is no longer recommended. Normal diet speeds recovery.
Anti-nausea medication
Ondansetron (Zofran) may be given for persistent vomiting to allow oral rehydration. Available by prescription. A single dose often allows successful oral rehydration.
IV rehydration
For moderate to severe dehydration when oral rehydration fails. IV normal saline bolus followed by maintenance fluids with electrolyte monitoring.
Probiotics
Lactobacillus rhamnosus GG or Saccharomyces boulardii may reduce the duration of diarrhea by 1 day. Evidence is moderate. Not a substitute for rehydration.
Home Care
- Offer small amounts of oral rehydration solution (Pedialyte) frequently — 1 teaspoon every 1-2 minutes
- Continue breastfeeding on demand
- Resume normal diet when vomiting subsides — do not restrict food
- Track wet diapers to monitor hydration (at least 4-6 per day)
- Offer popsicles made from oral rehydration solution for older toddlers
- Avoid apple juice, soda, and sugary drinks (can worsen diarrhea)
- Wash hands thoroughly after diaper changes
- Apply barrier cream to protect the diaper area from acidic diarrhea
When to Worry
Go to the ER if:
- Signs of severe dehydration — sunken eyes, no tears, lethargic, dry mouth, no wet diaper for 6+ hours
- Bloody diarrhea with high fever
- Child is limp, unresponsive, or inconsolable
- Persistent vomiting — cannot keep any fluid down for 8+ hours
- Green (bilious) vomiting in infants
- Severe abdominal pain or abdominal distension
- Signs of shock — rapid heart rate, cold extremities, mottled skin
Call your doctor if:
- Infant under 3 months with vomiting or diarrhea
- Signs of dehydration — dry mouth, fewer wet diapers, no tears
- Blood or mucus in stool
- Fever above 102F (39C) in a young child
- Vomiting lasting more than 24 hours
- Diarrhea lasting more than 5-7 days
- Child refuses all fluids
- Abdominal pain that is severe or localized to one area
Keep an eye on:
- Fewer than 4 wet diapers in 24 hours
- No tears when crying
- Sunken fontanelle in infants
- Child is increasingly lethargic or limp
- Diarrhea lasting more than 7 days
- Bloody stool
- Persistent vomiting preventing all oral intake for more than 12 hours
Prevention
- Rotavirus vaccine (oral, given at 2, 4, and 6 months)
- Thorough handwashing with soap and water (alcohol gel less effective against norovirus)
- Proper food handling and cooking
- Disinfect contaminated surfaces with bleach-based cleaner
- Keep sick children home from daycare for 48 hours after last vomiting/diarrhea
- Breastfeeding provides some protection
- Do not prepare food for others while ill
- Clean up vomit and diarrhea carefully wearing gloves
Contagion & Incubation
Incubation
1-3 days for most viral causes (norovirus 12-48 hours, rotavirus 1-3 days)
Contagious for
Most contagious during active symptoms and for 48-72 hours after symptoms resolve. Viral shedding in stool can continue for 2 weeks or longer, especially in young children.
Duration
Vomiting typically resolves in 1-2 days. Diarrhea usually lasts 3-7 days but may persist for up to 2 weeks. Full recovery including appetite return takes about 1 week.
Frequently asked questions
How long does gastroenteritis (stomach flu) last?
How does acute viral gastroenteritis spread?
When should I take my baby to the ER?
Can acute viral gastroenteritis be prevented?
When can my child return to daycare?
Sources
All content follows our editorial policy and is reviewed against published clinical guidelines.
2,705 evidence-based guides6 authoritative medical sources
Related Illnesses
Bottom line
Gastroenteritis (Stomach Flu) is a viral illness that typically resolves on its own. Seek emergency care if signs of severe dehydration — sunken eyes, no tears, lethargic, dry mouth, no wet diaper for 6+ hours.
Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.