Food Poisoning in Children: What to Watch For, What to Do

A child who has been eating happily and is now vomiting and miserable is alarming. Most of the time it's a self-limiting infection that will be over in a few days, but the watching is the hard part — knowing what to do, what to look for, and what crosses the line into "needs to be seen now." Food poisoning in children specifically follows some predictable patterns; recognising them helps you make the call.

For a comprehensive overview, see our complete guide to child health.

Food Poisoning vs Gastroenteritis vs "A Bug"

Strictly speaking, food poisoning = illness from a food contaminated with bacteria, viruses, parasites, or toxins. Gastroenteritis = the broader category of GI infection that includes person-to-person spread (rotavirus, norovirus). At home you usually can't tell which you've got, and treatment is the same: hydration, rest, watching for warning signs.

Children get food poisoning more easily than adults. Their stomach acid is less acidic (less bacterial killing), their immune systems are less experienced, and their hand-to-mouth habits are unrivalled. A toddler who has just licked the floor of a public bathroom is doing exactly what evolution designed them to do.

The Common Causes — and Their Tell-Tale Timelines

The time between eating and getting sick is one of the most useful clues to the cause.

Staphylococcus aureus toxin — 1 to 6 hours. The classic "wedding buffet" food poisoning. Sudden, dramatic vomiting, often with diarrhoea, usually no fever. The toxin is pre-formed in the food (typically dairy, cream, or cooked meat left at room temperature), so even brief reheating doesn't destroy it. Resolves within 24 hours.

Norovirus (the "winter vomiting bug") — 12 to 48 hours. Sudden vomiting, profuse diarrhoea, mild to moderate fever. Spreads in nurseries and schools rapidly. Self-limiting, usually 1 to 3 days.

Salmonella — 12 to 72 hours. Fever, vomiting, diarrhoea (sometimes bloody), abdominal cramps. Classic culprits: undercooked chicken, raw or runny eggs (less common in UK now due to British Lion mark), unpasteurised dairy, contact with reptiles or chicks. Symptoms usually settle in 4 to 7 days.

Campylobacter — 2 to 5 days. The single most common cause of bacterial food poisoning in the UK — UKHSA estimates around 280,000 to 500,000 cases per year. Often associated with undercooked chicken. Severe abdominal pain that can mimic appendicitis, bloody diarrhoea, fever. Lasts 5 to 7 days. Some children have a longer phase of post-infectious bowel sensitivity.

E. coli O157 (STEC) — 2 to 8 days. Less common but serious. Severe cramping, watery then bloody diarrhoea. Associated with undercooked minced beef, unpasteurised milk, contaminated water, contact with farm animals (a recurring outbreak source). Around 5 to 10% of paediatric cases progress to HUS — haemolytic uraemic syndrome — in the second week of illness.

Listeria — uncommon but dangerous in pregnancy and immunocompromised children. Found in soft cheeses, pâté, and ready-to-eat cold meats. Mostly relevant for what to avoid in pregnancy.

Bacillus cereus — 30 minutes to 6 hours, or 8 to 16 hours depending on toxin. Classic culprit: rice left out overnight then reheated. Vomiting predominant; resolves quickly.

What HUS Looks Like (and Why It Matters)

Haemolytic uraemic syndrome is the rare but important reason to take E. coli O157 seriously. It typically appears in the second week of illness, often after the diarrhoea is actually improving.

Signs:

• Reduced urine output — fewer wet nappies, much less wee than usual
• Pallor — looking unusually pale or "washed out"
• Unusual lethargy — much more tired than the illness itself would explain
• Bruising or unusual bleeding (low platelets)
• Dark, tea-coloured urine
• Swelling of face, hands, or feet

If your child has had bloody diarrhoea and is now developing any of these in the second week of illness, this is a medical emergency — go to A&E. Early treatment of HUS substantially affects outcomes. A child with HUS needs hospital admission.

At-Home Management: What to Do

The treatment of viral and bacterial gastroenteritis at home is essentially the same: replace fluids, rest, watch.

Oral rehydration solution (Dioralyte or equivalent). This is the active ingredient. The exact glucose-to-electrolyte ratio of ORS is what makes intestinal absorption work even when the gut is inflamed. Plain water doesn't replace lost electrolytes. Sugary squash and fruit juice make osmotic diarrhoea worse.

How to give it:

• Small, frequent sips — every few minutes — beats large gulps that come back up
• After each loose stool: aim for around 5 to 10 ml/kg of ORS over the following hour
• After each vomit: wait 15 to 30 minutes, then start small sips again
• A 200 ml dose split over an hour is very different from 200 ml in one go

Continue breastfeeding — uninterrupted. Breast milk hydrates and contains immune factors. Don't switch to water "to be gentler."

Don't dilute formula. Keep formula at standard strength.

Food. Don't withhold food once the worst of the vomiting has settled. The old "BRAT" diet (banana, rice, applesauce, toast) isn't necessary, but light, plain foods are often better tolerated than rich ones in the first 24 hours. Let appetite guide. A child who isn't yet asking for food doesn't need to be made to eat.

• Anti-diarrhoeals like loperamide — not for under-12s with infectious gastroenteritis. Stopping the diarrhoea traps the infection inside.
• Anti-emetics without medical advice — domperidone and ondansetron exist for severe cases but should be doctor-led.
• Probiotics — modest evidence in some specific situations; not the priority. Hydration first.

When to Get Medical Help

Same-day GP or 111 if:

• A baby under 3 months with any vomiting or diarrhoea
• A baby under 6 months with vomiting or diarrhoea lasting more than a few hours, or with reduced wet nappies
• Vomiting that is preventing any oral fluids staying down
• Fewer than 3 wet nappies in 24 hours (or much less wee for older children)
• Bloody diarrhoea at any age
• High fever (≥39°C) or fever lasting more than 3 days
• Severe abdominal pain (right lower quadrant, persistent, or making them double up — could mimic appendicitis)
• Symptoms lasting more than 7 days
• Returned from travel and now unwell — some travel-related causes need different treatment
• A child who looks unusually unwell, lethargic, or pale

A&E or 999 if:

• Signs of significant dehydration — sunken fontanelle in babies, dry lips and tongue, sunken eyes, no tears when crying, very floppy
• A child who is hard to rouse or unusually drowsy
• Repeated bilious (green) vomiting in a baby — possible obstruction
• A non-blanching rash
• Severe ongoing abdominal pain
• Suspected HUS signs (above)
• A child with a known immune-compromising condition who is unwell

When Antibiotics Are (and Aren't) Used

For most bacterial food poisoning in otherwise healthy children, antibiotics are not prescribed — the illness is self-limiting and antibiotics don't significantly shorten it.

Specific situations:

• Suspected E. coli O157: antibiotics are avoided — some evidence (and current PHE/UKHSA guidance) suggests they may increase the risk of HUS by causing rapid bacterial die-off and toxin release.
• Salmonella in healthy children: usually no antibiotic. In immunocompromised, very young (under 3 months), or severely unwell children, antibiotics may be used.
• Campylobacter: antibiotics shorten illness only modestly and are usually reserved for severe or prolonged cases.
• Giardia, amoebic dysentery, and other parasites: specific treatments after stool diagnosis.

A stool sample is sometimes requested — particularly with bloody diarrhoea, prolonged illness, recent travel, or in children at risk. The lab can identify the organism and inform decisions.

Prevention: The Things That Actually Reduce Risk

UK food poisoning rates in children are dominated by a few preventable scenarios.

1. Cook meat thoroughly. Particularly chicken (no pink inside, juices clear) and minced meat (cooked through). Whole steak can be served pink because contamination is on the surface, killed by searing; minced meat distributes contamination throughout, so cook through.

2. Don't reuse marinades that touched raw meat.

3. Wash hands before handling food and after handling raw meat.

4. Separate chopping boards for raw meat and other foods. Or wash thoroughly between.

5. Refrigerate leftovers within 1 to 2 hours of cooking. Cool large portions in shallow containers (cools faster). Reheat to steaming hot.

6. Reheat rice with care. Cooked rice left at room temperature is the classic Bacillus cereus risk. Refrigerate within an hour, eat within a day.

7. Don't wash chicken before cooking. This was traditional advice and it's wrong — splashing spreads campylobacter around the kitchen.

• Unpasteurised milk and dairy products
• Soft mould-ripened cheeses (brie, camembert, blue cheese) made from unpasteurised milk
• Raw or runny eggs in homemade mayonnaise, mousse — supermarket British Lion eggs are now considered safe runny for older children, but follow current Food Standards Agency advice for the age group
• Raw shellfish
• Pâté

9. Honey — not under 12 months (botulism risk).

10. Farm visits: lots of opportunities for E. coli O157. Wash hands thoroughly after touching animals, before eating, before going home.

11. Travel and street food with young children — stick to cooked-hot food, peeled fruit, bottled water in higher-risk areas.

After the Illness

A few things worth knowing about recovery:

• Lactose intolerance after gastroenteritis is common — the gut lining takes 1 to 2 weeks to recover, and lactose can cause continued loose stools during that period. Switching to lactose-free milk briefly can help if diarrhoea is dragging on.
• Post-infectious irritable bowel syndrome can follow significant gastroenteritis in some children. If bowel pattern is still off 4 weeks later, see the GP.
• Return to nursery or school: standard public health guidance is 48 hours after the last episode of diarrhoea or vomiting — not just symptom-free that morning.
• Hand hygiene at home matters during recovery — children continue to shed organisms in stool for days to weeks after symptoms resolve.

Most childhood food poisoning resolves at home with rest and oral rehydration over 2 to 5 days. The serious risk is dehydration in young children — replace fluids in small frequent sips with oral rehydration solution (Dioralyte or supermarket equivalent) rather than plain water or sugary drinks. Bloody diarrhoea, significant dehydration, high or prolonged fever, severe abdominal pain, or any vomiting and diarrhoea in a baby under 3 months means same-day medical review. E. coli O157 is the one to be especially careful about — bloody diarrhoea can be the precursor to haemolytic uraemic syndrome (HUS) in around 5 to 10% of paediatric cases. Antibiotics are not routinely prescribed for childhood food poisoning, and for suspected O157 they may make things worse.