Vomiting is one of the most common reasons parents contact their GP or seek urgent care, and it is often possible to manage safely at home once the underlying cause is identified and red flags have been excluded. The anxiety that vomiting provokes is understandable – a vomiting infant looks and sounds distressed – but in most cases the episode is self-limiting and the main task is maintaining hydration.
This guide covers the common causes of vomiting at different ages, how to manage it at home, and which signs should prompt urgent medical assessment.
Healthbooq (healthbooq.com/apps/healthbooq-kids) covers common childhood illnesses and when to seek help.
Common Causes by Age
Young infants (0-3 months). Bringing up small amounts of milk (posseting) is normal in the first weeks and months and reflects immaturity of the lower oesophageal sphincter rather than illness. Gastro-oesophageal reflux – more persistent regurgitation that may cause discomfort – is common and usually resolves without treatment.
Pyloric stenosis is an important cause of vomiting in young infants, typically presenting between 2 and 8 weeks with progressive, forceful projectile vomiting after feeds. It is caused by hypertrophy (thickening) of the pyloric muscle, which narrows the outlet from the stomach. The classic description is vomiting so forceful it lands at a distance. A baby with pyloric stenosis is hungry and feeds eagerly immediately after vomiting. Pyloric stenosis requires surgical correction (pyloromyotomy) and is not a condition to manage at home; persistent projectile vomiting in a young infant warrants prompt clinical assessment.
Infants and toddlers (3 months-3 years). Viral gastroenteritis is the most common cause in this age group. Rotavirus was historically the leading cause; since routine vaccination was introduced into the NHS childhood schedule in 2013, rotavirus-related hospitalisations have fallen substantially. Other viruses including norovirus and adenovirus cause gastroenteritis at all ages.
Food allergy or intolerance can cause vomiting, sometimes alongside rash, diarrhoea, or other symptoms. Intussusception – where one portion of bowel telescopes into another – is a surgical emergency that presents in infants aged 3 months to 3 years with severe intermittent abdominal pain, vomiting, and eventually blood in the stool (often described as redcurrant jelly stool). This requires urgent assessment.
Older children. Gastroenteritis remains common. Appendicitis typically presents with central abdominal pain that migrates to the right iliac fossa, associated with vomiting, fever, and loss of appetite. Cyclic vomiting syndrome – a pattern of recurrent, stereotyped episodes of intense vomiting separated by symptom-free periods – affects around 1-2% of school-aged children and is associated with migraine in many families.
Managing Vomiting at Home
For viral gastroenteritis without red flags, management is supportive:
Oral rehydration. The priority is preventing dehydration. Oral rehydration solution (ORS such as Dioralyte) replaces salts and fluids more effectively than water or diluted juice, which can worsen electrolyte imbalance if given in large amounts. Small, frequent sips (5-10ml every few minutes) are far better tolerated than larger volumes, which are likely to be vomited immediately.
Resuming feeds. Breastfed babies should continue to breastfeed. Formula-fed infants should resume normal formula as soon as they can tolerate it – prolonged withholding of formula is not recommended. Children who have started solids can resume a normal diet as tolerated; the BRAT diet (bananas, rice, applesauce, toast) is no longer specifically recommended, though bland foods are often preferred initially.
Anti-emetic medication. Ondansetron is widely used in paediatric emergency settings to reduce vomiting and improve oral rehydration success, but it is not routinely prescribed for home use in the UK. Research by Freedman and colleagues at the University of Calgary, published in NEJM (2006), demonstrated that ondansetron given in emergency departments significantly reduced the need for IV rehydration and hospital admission. In practice, ondansetron is generally reserved for severe presentations in clinical settings.
Signs of Dehydration
Dehydration is the main risk. Signs that suggest significant dehydration and prompt urgent assessment: sunken fontanelle (in young infants), significantly reduced wet nappies or urination, dry mouth and lips, sunken eyes, no tears when crying, unusual drowsiness, and mottled or pale skin. Mild dehydration may be managed at home with ORS; moderate or severe dehydration requires clinical assessment and may require intravenous fluids.
Red Flags: When to Seek Urgent Help
Urgent assessment is needed for any of the following: bilious (green or yellow-green) vomiting in any age, which suggests possible bowel obstruction; blood in the vomit; severe or persistent abdominal pain; signs of dehydration; altered consciousness or unusual sleepiness; vomiting after a head injury; vomiting in an infant aged 2-8 weeks that is forceful and projectile; and vomiting that has not improved after 24 hours in an infant under 3 months.
Key Takeaways
Most vomiting in children is caused by viral gastroenteritis and resolves without treatment beyond careful oral rehydration. The main risk is dehydration, which develops faster in young infants. Oral rehydration solution (ORS) is the first-line treatment; small, frequent sips are more effective than large volumes. Red flags that require urgent assessment include persistent bilious (green) vomiting, blood in vomit, severe abdominal pain, signs of dehydration, altered consciousness, or vomiting following a head injury. Pyloric stenosis presents with forceful projectile vomiting in infants aged 2-8 weeks.
