Stomach Bugs in Children: Keeping Them Hydrated and When to Worry

More than 50 children have come down with vomiting at Oasis Primary School, Singapore. What exactly happened?

The note in the school bag says a bug is going round the class. By the next evening your child is bent over a basin at 2am and you’re wondering how much of this is normal. Stomach flu and its cousins move through schools and childcare centres quickly, and most cases are mild and pass in a few days. What matters at home is keeping fluids going in, and spotting the point where it stops being mild.

Most childhood tummy bugs are viral, like norovirus or rotavirus, and clear in a few days. The priority is fluids, in small frequent sips, to prevent dehydration. Keep a sick child home until 48 hours after the last vomiting or diarrhoea.

The warning signs to act on are signs of dehydration: little or no urine, no tears, a dry mouth and unusual drowsiness.

What causes it

Gastroenteritis, the stomach bug, is inflammation of the gut that causes vomiting and diarrhoea. In children it’s usually viral:

Norovirus, highly contagious, causes sudden vomiting and diarrhoea and sweeps through schools and childcare centres. It spreads through contaminated hands, surfaces and food.
Rotavirus, a common cause in young children, now less so where the rotavirus vaccine is given.
Hand, foot and mouth disease (HFMD), endemic in Singapore, is a different virus but spreads the same way and often runs through the same classrooms, with mouth ulcers and a rash on hands and feet alongside fever.

Less often, a bacterial infection from contaminated food causes it, which can be more severe and may need a doctor. Vomiting that comes on within minutes of a meal, especially with hives, swelling or breathing trouble, is a different picture altogether: read up on the signs of food allergy and anaphylaxis in children so you can tell the two apart quickly.

The main job: hydration

A child rarely comes to harm from a few days of vomiting itself. Dehydration is the risk, so everything comes back to keeping fluids in:

Small, frequent sips beat big drinks that come straight back up. A spoonful or a sip every few minutes adds up.
Oral rehydration salts (ORS) from the pharmacy are the best fluid, replacing salts as well as water. Follow the packet, and keep some at home.
Breast or formula milk continues for babies; breastfeed more often.
Avoid sugary drinks and undiluted juice, which can worsen diarrhoea.
Food can wait a little. Once vomiting settles, offer plain foods, but fluids come first, and there’s no need to force eating.

Home remedies get passed around for every childhood illness, and soup is the classic one. If you’re curious about what really helps a child’s cold, the same principle applies here: warm fluids comfort, but they don’t shorten a virus.

When to see a doctor

Take your child to a doctor, or A&E if severe, if you see:

Signs of dehydration: little or no urine (a dry nappy for many hours), no tears when crying, a dry mouth, sunken eyes, unusual drowsiness or floppiness
Vomiting that won’t stop, or an inability to keep any fluid down
Blood in the vomit or stool
A high fever, severe tummy pain, or a swollen, tender abdomen
Green (bile-stained) vomit
A baby under six months with vomiting and diarrhoea, who dehydrates faster
Symptoms dragging on beyond about a week

A baby’s dehydration can move quickly, so the threshold to seek help is lower the younger the child.

Stopping it spreading

These bugs travel on hands and surfaces, so hygiene at home and following the school’s rules keeps it from going round the family and the class:

Keep the child home until at least 48 hours after the last episode of vomiting or diarrhoea, which is standard school and childcare guidance.
Wash hands with soap, thoroughly and often, especially after the toilet and before food. Hand sanitiser is less effective against norovirus than soap and water.
Clean surfaces, toilets and toys with a bleach-based cleaner, since these viruses linger.
Don’t share towels, cups or cutlery while anyone is ill.
Tell the school if your child has HFMD or a confirmed bug, so others can be watched.
Consider the rotavirus vaccine for babies, available in Singapore, which prevents one common cause.

While you’re checking the vaccination card, it’s worth confirming the rest is up to date too. Outbreaks in the region have put measles and the MMR vaccine back in the news, and a missed dose is easy to overlook once the baby years are behind you.

Common questions

How do I keep a child with a stomach bug hydrated?

Give small, frequent sips rather than big drinks, and use oral rehydration salts from the pharmacy, which replace salts as well as water. Keep breast or formula milk going for babies, and avoid sugary drinks.

When should I take my child to the doctor for vomiting or diarrhoea?

If there are signs of dehydration (little urine, no tears, dry mouth, drowsiness), constant vomiting, blood in vomit or stool, high fever or severe tummy pain, green vomit, or a baby under six months affected. See a doctor sooner for younger children.

How long should a child stay home with a stomach bug?

Until at least 48 hours after the last episode of vomiting or diarrhoea, the standard school and childcare guidance, since they remain contagious.

How do I stop a stomach bug spreading at home?

Wash hands with soap often, clean surfaces and toilets with a bleach-based cleaner, don’t share towels or cutlery while anyone is ill, and keep the sick child’s things separate.

Is hand sanitiser enough against norovirus?

No. Soap and water is more effective against norovirus than alcohol hand sanitiser, so wash hands properly, especially after the toilet and before eating.

Getting through the next 48 hours

Buy the oral rehydration salts before you need them, because the shops feel very far away at midnight. Then it comes down to patience: a sip every few minutes, a fresh set of sheets, and your eyes on the nappies and the toilet trips. If the urine dries up, the tears stop or your child goes floppy and hard to rouse, that’s your cue to see a doctor, and much sooner for a baby. Keep them home the full 48 hours after the last episode, even when they seem fine, and wash your own hands like you mean it. The parent who nurses everyone through this is usually the next one down.