How long it normally lasts

The NHS gives clear timings for a stomach bug: "vomiting usually stops in 1 or 2 days", and diarrhoea, if it comes too, usually stops within 5 to 7 days. Most toddler vomiting is viral, self-limiting and needs nothing but fluid and patience.

NICE guideline CG84 covers acute diarrhoea and vomiting caused by gastroenteritis in children under 5, and exists partly to standardise when care needs to be escalated — a reminder that the management question is mostly about hydration and safety-netting rather than about stopping the vomiting itself.

Fluid first, food later

The NHS advice is short and specific: rest at home, and drink lots of fluids such as water or squash, taking small sips if feeling sick. Keep breast or bottle feeding, offering smaller feeds more often than usual. Eat when able to, avoiding fatty or spicy foods.

It is equally specific about what not to do:

do not give fruit juice or fizzy drinks, because they can make diarrhoea worse;
do not make baby formula weaker — use it at its usual strength;
do not give children under 12 medicine to stop diarrhoea;
do not give aspirin to children under 16.

The HSE adds the reassurance most parents need: "do not worry if your child doesn't want to eat. It's more important that they drink plenty of fluids." The American Academy of Pediatrics suggests keeping a child off solid food for roughly the first 24 hours of an illness that causes vomiting, and encouraging small amounts of an electrolyte solution instead, because liquids are less likely than solids to stimulate more vomiting.

If your pharmacist recommends oral rehydration powder, follow the instructions on the pack. This page does not give amounts, and the AAP's own guidance is that fluid requirements are set by a clinician based on the individual child.

The practical version at 2am

Very small amounts, very often, beats a full cup that comes straight back. A teaspoon or a small sip every few minutes, offered from a spoon, syringe or open cup, is the technique that works with a toddler who has just been sick and does not want to see a drink. Wait 15 to 20 minutes after a vomit before restarting. Ice lollies count as fluid and are often accepted when nothing else is.

Spotting dehydration

This is what all the fluid advice is protecting against. The HSE lists the signs of dehydration in babies and children as fewer wet nappies than usual, nappies that do not feel as heavy, being less energetic or responsive than usual, dark yellow urine, and complaining of a headache. Thirst is one of the earliest signs.

The AAP separates mild to moderate from severe. Mild to moderate: playing less than usual, urinating less frequently, a parched dry mouth, fewer tears when crying, and a sunken soft spot in an infant or toddler. Severe adds being very fussy, excessively sleepy, sunken eyes, cool or discoloured hands and feet, wrinkled skin, and urinating only once or twice a day.

The HSE says to take a child urgently to a GP or emergency department if they seem drowsy or hard to wake, are breathing fast, have few or no tears when they cry, have a sunken fontanelle, have a dry mouth, have not passed urine in the last 12 hours, are pale, have less energy than usual, have fewer than three wet nappies a day, or seem confused.

When to call 111

The NHS lists these as urgent-advice reasons to call 111:

you are worried about a baby under 12 months;
your child stops breast or bottle feeding while they are ill;
a child under 5 has signs of dehydration, such as fewer wet nappies;
you or your child keep being sick and cannot keep fluid down;
there is bloody diarrhoea or bleeding from the bottom;
diarrhoea lasts more than 7 days, or vomiting more than 2 days.

The HSE's threshold for contacting a GP is more granular and useful for a toddler: vomiting more than 3 times in the past 24 hours; vomiting for more than 3 days; signs of dehydration; recent travel abroad; a high temperature; severe tummy pain; or bloody, brown or green vomit.

When to call 999 or go to A&E

The NHS lists immediate-action signs: vomiting blood, or vomit that looks like ground coffee; yellow-green or green vomit in a child; possibly having swallowed something poisonous; a stiff neck and pain when looking at bright lights; a sudden severe headache; a sudden severe tummy ache; blue, grey, pale or blotchy skin, lips or tongue (easier to see on the palms or soles on brown or black skin); severe difficulty breathing or fast shallow breathing; or being confused or not responding as usual.

The HSE adds a specific ambulance trigger: call 999 if your child has a headache, stiff neck, rash and is vomiting. It also advises going straight to an emergency department for pain that gets worse quickly and spreads across the tummy.

When it is not a bug

Vomiting is a symptom of many things other than gastroenteritis, which is why the red flags above matter more than the number of vomits. The HSE names infections such as meningitis, pneumonia and urinary tract infections, reflux, milk intolerance and food allergies, and conditions affecting the intestines such as pyloric stenosis or intussusception, along with strangulated hernia and appendicitis. A vomiting toddler with no diarrhoea, who is in pain, or who is getting worse rather than better, needs assessing rather than waiting out.

Stopping it spreading

The NHS advises staying off nursery or work until 48 hours after the last episode of vomiting or diarrhoea, washing hands frequently with soap and water, washing soiled clothing and bedding separately on a hot wash, cleaning toilet seats, flush handles, taps, surfaces and door handles daily, avoiding preparing food for others, not sharing towels, flannels or cutlery, and staying out of swimming pools for at least 48 hours after symptoms stop.

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