Sickness and Diarrhoea: The 48-Hour Rule Explained

My School Agent | 8 July 2026

She threw up at 3am on a Tuesday. Then again at 4am. Then nothing. By Wednesday morning she was watching telly and asking for toast.

Could she go back to school? Technically no. The 48-hour rule.

Technically it was only 30 hours since the last vomit. But she felt fine. She was bored. I had meetings. Surely the rule was for children who were still unwell?

The rule is not for children who are still unwell. The rule is for the other children in the class who don't want to be next.

The 48-Hour Rule

Children must stay off school for 48 hours after the last episode of vomiting or diarrhoea.

Not 48 hours from when they first got ill. From the last time they were sick.

If your child vomits on Monday morning, seems fine Monday afternoon, then vomits again Monday night, the clock resets. They can return to school on Thursday morning (48 hours after the Monday night episode).

This rule applies even if your child feels completely fine. Even if they're bouncing around asking to go back. Even if you're certain it was a one-off and not a bug.

Why 48 Hours?

Most vomiting and diarrhoea in children is caused by norovirus or rotavirus. Both are extremely contagious.

The virus spreads through tiny particles of vomit or faeces. You don't need to touch the sick itself. Touching a contaminated door handle, toilet flush, or toy is enough.

Children are contagious from before symptoms start until 48 hours after symptoms stop. That's why the rule is 48 hours from the last episode, not from when they feel better.

Your child might feel fine on day 2. But they're still shedding the virus. They can still infect the entire class.

Schools enforce the 48-hour rule to stop outbreaks. When one child breaks the rule and returns too early, six more children go home sick by Friday. Then their siblings get it. Then their parents get it. Then half the class is off the following week.

What Schools Enforce

Most schools follow the NHS 48-hour guidance. Some are stricter.

If your child is sent home from school after vomiting, they can't return until 48 hours after that episode. The school office will tell you this when you collect them.

If your child vomits at home and you keep them off school, you need to tell the school it's vomiting or diarrhoea (not just "unwell"). The office will note the 48-hour rule and expect them back after that.

Some parents say "tummy bug" or "not feeling well" to avoid triggering the 48-hour countdown. Schools know this trick. If your child looks fine when you collect them, the office may ask directly: "Was it vomiting or diarrhoea?"

The Morning-Sick Dilemma

Your child wakes up, vomits once, then seems fine. Do you keep them off school?

If it's an isolated vomit and they have no other symptoms, it might not be a bug. It could be:

Coughing fit that triggered vomiting (common with colds)
Ate something dodgy
Anxiety about a test or presentation
Reflux or mild food intolerance

The safe answer is to keep them home and see if it happens again. If they vomit once more, it's a bug. 48-hour rule starts.

If they don't vomit again, have no diarrhoea, and feel completely well, some parents send them in the next day. This bends the rule. Schools differ on how strict they are.

My rule: if there's any doubt, keep them home. One extra day at home is better than starting an outbreak.

What About Diarrhoea?

Same rule. 48 hours from the last episode of diarrhoea.

Diarrhoea means loose, watery stools. Not just "a bit soft." If it's formed enough to hold its shape, it doesn't count as diarrhoea for the 48-hour rule.

This gets tricky with younger children who might not tell you clearly what happened. If your child had an upset tummy and you're not sure if it was diarrhoea, assume it was. Better safe than spreading norovirus.

When to Call the GP

Most vomiting and diarrhoea bugs clear up on their own within 2-3 days. You don't need to see a doctor.

Call your GP or NHS 111 if:

Your child has blood in their vomit or stools
They're vomiting for more than 2 days
They have diarrhoea for more than 5 days
They show signs of dehydration (dry mouth, sunken eyes, no tears when crying, not weeing much)
They have a high fever that won't come down
They're unusually drowsy or unresponsive
They have severe tummy pain

Preventing Spread at Home

If one child has a vomiting bug, the rest of the household is probably next. You can't entirely prevent this, but you can reduce the risk.

Wash hands obsessively. Hot water, soap, 20 seconds. Every time anyone uses the toilet, before eating, after touching the sick child.
Bleach-clean contaminated surfaces. Door handles, toilet flush, taps, light switches. Norovirus survives on surfaces for days.
Wash contaminated clothes and bedding separately at 60°C or higher. Don't shake them out first (this spreads the virus).
Use separate towels. Don't share flannels or hand towels.
Keep the sick child away from food prep areas. Don't let them "help" make dinner.

Hand sanitiser doesn't kill norovirus. Only soap and water works.

The Long View

Stomach bugs are miserable. The 48-hour rule feels punitive when your child is clearly better. But it works.

Every parent has been tempted to cut it short. Most of us have learned the hard way why the rule exists.

I built My School Agent to take some of the logistical pressure off these situations. When your child is off sick for 3 days and you're behind on emails, behind on washing, behind on everything, the last thing you need is to manually track what homework they missed and when the next mufti day is. Let the app handle that. You handle the sick bowl.