Vomiting and diarrhoea in children — keeping your child hydrated, and knowing when to worry

About this guide

Vomiting and diarrhoea, usually together and usually from a viral infection, are among the commonest childhood illnesses. Most children are better within a few days without any medicine at all. The one thing that matters, and the thing that occasionally lands a child in hospital, is dehydration. Almost all of the advice in this guide comes down to keeping enough fluid going in while the illness runs its course.

What causes it

Viruses cause most gastroenteritis in children:

• Rotavirus, once the leading cause of severe diarrhoea in infants and toddlers. Cases have fallen since the rotavirus vaccine became available; it is given by mouth in the first months of life and is part of Singapore’s National Childhood Immunisation Schedule (NCIS).
• Norovirus, the classic “winter vomiting bug” that sweeps through families, preschools and cruise ships in any season. It causes sudden, forceful vomiting, needs only a few virus particles to spread, and survives on surfaces.
• Adenovirus and astrovirus, which tend to cause a longer, milder diarrhoea.

Bacteria such as Salmonella, Campylobacter and some strains of E. coli cause a smaller share, often with higher fever, crampy pain and sometimes blood in the stool, and often traced to undercooked eggs or poultry, unpasteurised products or contaminated food. Parasites such as Giardia are uncommon in Singapore but worth considering after travel.

Not all vomiting is gastroenteritis. Vomiting without diarrhoea, especially if it goes on for more than a day, can be the first sign of something else: a urine infection, an ear infection, meningitis, appendicitis, a bowel blockage (intussusception in babies and toddlers), or, in an older child, diabetes. That is why vomiting alone gets more attention from us than vomiting with diarrhoea.

What to expect

• Vomiting usually starts first and settles within 1 to 2 days.
• Diarrhoea follows and typically lasts 5 to 7 days, occasionally up to two weeks. Stools may be watery, greenish and frequent.
• A mild fever, tummy cramps and poor appetite are common in the first days.
• Once the vomiting stops, most children keep fluids down and steadily improve.

Dehydration: what to look for

A child loses water and salts with every vomit and every loose stool. Babies and toddlers become dehydrated faster than older children because they are small and cannot ask for a drink.

Any sign in the last column means a children’s emergency department now, or 995.

How to rehydrate at home

Oral rehydration solution (ORS) is the treatment for gastroenteritis. It is a measured mix of glucose and salts (brands in Singapore include Hydralyte and Pedialyte, as sachets, ready-made bottles or ice blocks) that the gut absorbs even while it is inflamed. Plain water on its own replaces water but not salts, and large volumes of it can make things worse in a small child.

The method that works:

1. Small amounts, very often. About 5 mL (one teaspoon) every 1 to 2 minutes, using a spoon, a syringe or a small cup. A child who gulps a whole cup usually vomits it straight back. Small sips are much more likely to stay down. This is tedious for the parent and it works.
2. After each vomit, wait 10 to 15 minutes, then start again with small sips.
3. After each loose stool, give extra: roughly 10 mL per kilogram of body weight (for a 10 kg toddler, about 100 mL) on top of normal drinks.
4. Flavour matters. Chilled ORS, or ORS ice blocks, are taken more readily than warm ORS. Do not dilute it or add cordial; the concentration is what makes it work.
5. Breastfed babies should keep breastfeeding, more frequently and for shorter feeds if needed, with ORS in between. Formula-fed babies should continue their usual formula at full strength; there is no need to dilute it or switch brands.

Drinks to avoid: soft drinks, fruit juice, cordial, isotonic sports drinks and glucose drinks. They are too sugary and have the wrong balance of salts, and they can pull more water into the gut and worsen diarrhoea. Home-made salt and sugar mixtures are risky unless measured exactly; a pharmacy sachet is safer.

What to feed

The old advice to starve the gut is out of date. Offer normal food as soon as your child wants it, ideally within 24 hours, even if the diarrhoea is continuing. Early feeding shortens the illness. Sensible choices in the first days: rice, porridge, bread, noodles, potatoes, plain crackers, bananas, soups, lean meat, eggs, yoghurt. There is no need for a restrictive “BRAT” diet or for lactose-free milk in most children; if the diarrhoea clearly worsens with milk after a week, ask us.

Avoid very fatty, spicy or sugary foods until the stools are settling.

Medicines: mostly none

• Anti-diarrhoeal medicines such as loperamide (Imodium) should not be given to children. They can cause serious side effects and do not shorten the illness.
• Anti-vomiting medicines are not for routine home use. In the clinic, we sometimes give a single dose of ondansetron to a child who cannot keep ORS down; it reduces vomiting for a few hours and can avoid a hospital trip for a drip. It is a doctor’s decision, not an over-the-counter one.
• Antibiotics do not help viral gastroenteritis and are not routinely given even for most bacterial causes, which settle on their own. They are used in specific situations, for example a very young baby, a child with a weakened immune system, or certain bacteria identified on a stool test.
• Probiotics have been studied extensively; the better-quality recent trials show little or no benefit, and we do not routinely recommend them.
• Zinc is recommended by the World Health Organization for children in countries where zinc deficiency is common. It is not needed for well-nourished children in Singapore.
• Paracetamol for fever or tummy discomfort is fine, dosed by weight. Ibuprofen is best avoided while a child is vomiting or at risk of dehydration.

Preventing spread

Gastroenteritis is highly contagious.

• Wash hands with soap and water after every nappy change or toilet visit, and before preparing food. Alcohol hand rub is not reliable against norovirus.
• Clean surfaces (toilet, taps, high chair, toys) with a bleach-based household cleaner. Vomit should be cleaned up promptly with gloves and the area disinfected.
• Wash soiled clothing and linen separately on a hot cycle.
• Keep your child home from preschool, school and swimming until 48 hours after the last vomit or loose stool.
• Food safety: cook eggs and poultry thoroughly, keep cooked and raw food separate, and refrigerate leftovers promptly.
• The rotavirus vaccine, given by mouth in early infancy, is the single most effective way to prevent severe rotavirus disease. Ask us if your baby has not had it.

When to see a doctor

Come in the same day if:

• Your baby is under 6 months and vomiting or having frequent loose stools
• There are signs of dehydration (middle column of the table above): fewer wet nappies, dry mouth, unusual tiredness
• Your child cannot keep any fluid down despite small sips for several hours
• Vomiting continues beyond 24 hours, or vomiting without diarrhoea goes on for more than a day
• Diarrhoea lasts more than 7 days
• There is a high fever, or severe or persistent tummy pain
• Your child has recently travelled, or has a long-term condition
• You need a medical certificate for school or childcare
• You are worried

Go to a children’s emergency department or call 995

• Signs of severe dehydration: no urine for 8 hours, drowsy, floppy, hard to wake, sunken eyes, cold hands and feet
• Green (bile-stained) vomit, or vomit containing blood
• Blood in the stool in a child who is unwell
• Severe tummy pain, especially pain that is constant or that makes the child draw up the legs and scream in episodes (possible intussusception in babies and toddlers)
• A swollen, hard tummy
• A non-blanching rash, a stiff neck or a bulging fontanelle
• Fast breathing, or breath that smells sweet or of nail-polish remover in an older child (possible diabetes)

How we manage gastroenteritis at our Punggol clinic

Children with vomiting or diarrhoea are seen as walk-ins, Monday to Saturday, and can be booked online. At the visit:

• We check hydration properly: weight, the signs in the table, and how much has been going in and coming out. Weighing a child and comparing with a recent weight is one of the most useful measures we have.
• We look for the causes that are not gastroenteritis, especially in a child who is vomiting without diarrhoea: ears, throat, tummy, urine.
• A supervised ORS trial in the clinic for a child who is struggling, sometimes with a single dose of ondansetron, so that you go home with a child who is keeping fluids down and a clear plan for the next 24 hours.
• Stool tests when they would change management: blood in the stool, prolonged diarrhoea, recent travel, or an outbreak.
• A medical certificate covering the 48-hour exclusion period.
• Referral to a children’s emergency department for intravenous or nasogastric fluids when a child is dehydrated and cannot be rehydrated by mouth, with a letter so that treatment is not delayed.

Cross-links

• Fever in children
• Hand, foot and mouth disease: mouth ulcers that stop a child drinking
• Constipation in children: the other common childhood tummy problem
• Childhood vaccinations (NCIS): including the rotavirus vaccine

Get in touch

Punggol: 658 Punggol East, #01-04, Singapore 820658 · Tel 6312 4589 · Walk-ins welcome Mon–Sat

Joo Chiat: 172 Joo Chiat Road, #01-01, Singapore 427443 · Tel 6920 1952 · By appointment

Email: admin@ktmc.sg

References

• National Institute for Health and Care Excellence (NICE). Diarrhoea and vomiting caused by gastroenteritis in under 5s: diagnosis and management. Clinical guideline CG84. 2009. nice.org.uk
• Guarino A, Ashkenazi S, Gendrel D, et al. European Society for Paediatric Gastroenterology, Hepatology and Nutrition / European Society for Paediatric Infectious Diseases evidence-based guidelines for the management of acute gastroenteritis in children in Europe: update 2014. J Pediatr Gastroenterol Nutr. 2014;59(1):132–152.
• HealthHub, Ministry of Health Singapore. Gastroenteritis in children and Dehydration in children. healthhub.sg
• KK Women’s and Children’s Hospital (KKH). Acute gastroenteritis, patient information. kkh.com.sg
• Ministry of Health Singapore. National Childhood Immunisation Schedule (NCIS). moh.gov.sg
• Freedman SB, Williamson-Urquhart S, Farion KJ, et al. Multicenter trial of a combination probiotic for children with gastroenteritis. N Engl J Med. 2018;379:2015–2026.
• Fedorowicz Z, Jagannath VA, Carter B. Antiemetics for reducing vomiting related to acute gastroenteritis in children and adolescents. Cochrane Database Syst Rev. 2011;(9):CD005506.
• World Health Organization. The treatment of diarrhoea: a manual for physicians and other senior health workers. 4th revision, 2005.

This information is for general education only and is not a substitute for medical advice. Fluid and medicine amounts depend on your child’s weight and condition; please check with our team. v1.0 · September 2026 · Review due September 2028.