Vomiting in Infants: Causes and When to Worry

Spit-up vs vomiting

About half of babies spit up every day in the first months. It is called "happy spitting" when the baby is feeding and growing well. It is laundry, not a medical problem.

Common causes of vomiting in babies

Viral gastroenteritis

Viral gastroenteritis is the most common cause. Norovirus and rotavirus are typical. Vomiting usually starts first, then diarrhea, sometimes with fever. Vomiting usually stops within 1 to 2 days, though diarrhea can last up to a week. The rotavirus vaccine has greatly reduced severe cases.

Overfeeding and swallowed air

Large feeds, fast bottle flow and swallowed air during feeds can cause larger spit-ups or vomiting.

Gastroesophageal reflux

When spit-up is frequent and comes with poor weight gain, feeding refusal, arching, breathing problems or blood, it may be gastroesophageal reflux disease rather than simple reflux.

Cow's milk protein allergy

Milk protein allergy can cause vomiting, fussiness, eczema, and mucus or blood in stools. It affects formula-fed and breastfed babies. A severe delayed form, FPIES, causes repeated vomiting 1 to 4 hours after a trigger food, sometimes with lethargy and pallor.

Infections elsewhere

Ear infections, urinary tract infections, pneumonia and meningitis can all cause vomiting in babies. Vomiting with fever, irritability or lethargy needs prompt assessment.

Serious causes not to miss

• Pyloric stenosis: thickening of the muscle at the stomach outlet. Babies aged 2 to 8 weeks develop forceful, projectile vomiting after feeds, are hungry again right away, and may lose weight and become dehydrated. More common in firstborn boys. Treated with a small operation.
• Malrotation with volvulus: the bowel twists and cuts off its blood supply. Sudden green vomiting, usually in the first weeks of life. A surgical emergency.
• Intussusception: bowel telescoping, most often between 6 months and 3 years. Episodes of severe crying with legs drawn up, vomiting (later green), lethargy and "redcurrant jelly" stools.
• Hernia that becomes stuck, with a tender lump in the groin.
• Head injury, metabolic disorders and raised pressure in the skull, which are rare.

Vomiting by age

Signs of dehydration in babies

• fewer wet diapers (fewer than 6 a day in young infants, or none in 6 to 8 hours)
• dark, strong-smelling urine
• dry mouth and lips, no tears when crying
• sunken soft spot on top of the head or sunken eyes
• unusual sleepiness or irritability
• cool hands and feet

What to do when your baby is vomiting

Keep fluids going

• Breastfed babies: keep breastfeeding, but offer shorter, more frequent feeds, for example every 1 to 2 hours.
• Formula-fed babies: offer smaller amounts more often. Do not dilute formula.
• Oral rehydration solution (ORS): if vomiting is frequent, give small amounts with a spoon or syringe, about 5 ml (1 teaspoon) every 1 to 2 minutes, and increase slowly as it stays down. Ask your doctor or pharmacist about amounts by weight.
• Do not give plain water to babies under 6 months, juice, sports drinks or soda.
• Once vomiting has eased, go back to normal milk feeds. Babies on solids can restart usual foods within 24 hours.

Other care

• Hold your baby upright for 20 to 30 minutes after feeds.
• Burp during and after feeds.
• Lay your baby on their back to sleep, as always, even if they spit up. Do not use wedges or positioners.
• Do not give anti-nausea medicines unless a doctor prescribes them.

How doctors assess a vomiting baby

A doctor will ask about the color and force of vomiting, how often, feeds, wet diapers, stools, fever and weight. They will weigh your baby, check hydration, and examine the belly for swelling, tenderness or a lump. Tests may include urine tests, blood tests for hydration and salts, an abdominal ultrasound (for pyloric stenosis or intussusception) and an upper GI contrast study (for malrotation).

Frequently asked questions

How do I know if my baby is spitting up or vomiting?

Spit-up flows out easily in small amounts, usually soon after a feed, and the baby stays content. Vomiting is forceful, larger in amount, and the baby may be upset or seem unwell. Frequent spit-up in a happy, growing baby is normal.

When should I worry about my baby vomiting?

Seek emergency care for green vomit, blood, a swollen belly, severe crying episodes, a floppy or very drowsy baby, or signs of dehydration. Call your doctor promptly for projectile vomiting in a young baby, fever under 3 months, or vomiting lasting more than 12 to 24 hours.

What does projectile vomiting in a baby mean?

Occasional forceful vomiting can happen with overfeeding or a stomach bug. Repeated projectile vomiting after feeds in a baby aged 2 to 8 weeks who still seems hungry suggests pyloric stenosis, which needs prompt assessment and an ultrasound.

Why is my baby's vomit green?

Green or yellow-green vomit usually means bile, which can signal a blockage or twisting of the bowel. This is an emergency in babies. Take your baby to the ER immediately, even if they otherwise seem well.

Should I keep feeding my baby after vomiting?

Yes. Continue breast milk or formula in smaller, more frequent amounts. Oral rehydration solution in small sips helps if vomiting is frequent. Stopping feeds entirely raises the risk of dehydration.