Norovirus: the winter vomiting bug, the fluids, and the 48-hour quarantine
Last updated September 3, 2026.
Norovirus is the winter vomiting bug: sudden, violent vomiting and watery diarrhea, sometimes with aching and fever, running through households, schools, and cruise ships, and resolving by itself in two to three days. There is no treatment to kill it (antibiotics do nothing for viruses): the whole management is fluids (the dehydration is the only genuine danger, for the very young, the elderly, and the frail), rest, and the strict quarantine-and-bleach hygiene that stops it taking the whole house.
What does it feel like?
The arrival is abrupt: nausea detonating into projectile vomiting, watery diarrhea, sometimes both at once, with aching limbs, a headache, and a mild fever: misery for 24-72 hours, then recovery as sudden as the onset. It is spread terrifyingly easily (a few virus particles infect: the vomit aerosolizes them), which is why one family member's midnight episode is so often the household's by the weekend.
Why does it happen?
Norovirus is a highly contagious gut virus spread by the fecal-oral route: contaminated hands, surfaces, food, and the aerosolized vomit particles (which is why outbreaks sweep closed communities). The immunity after an infection is short and strain-specific, so repeat infections across life are normal. It circulates all year with the winter peak, and its superpower is its hardiness (it survives on surfaces for days and resists many cleaners: hence the bleach rule).
What actually helps?
- Fluids in small, frequent sips: the whole treatment: water, squash, or the oral rehydration sachets for the vulnerable: little and often beats big gulps, which bounce back.
- The reintroduction: food when the appetite returns (no need for the fasting rituals: eat what appeals), and no anti-diarrhea tablets for children.
- The 48-hour quarantine: stay home from work, school, and the hospital visit until 48 hours after the last episode: the virus sheds while you feel recovered.
- The hygiene that works: soap and water (the alcohol gels do not kill it), the bleach-based cleaner on the surfaces, the toilet flushed with the lid down, and the contaminated laundry hot-washed.
- Who needs help sooner: the baby refusing fluids, the frail elder, and anyone with signs of dehydration (passing little urine, very dry mouth, dizziness, listlessness).
When is it an emergency?
The dehydration markers (same-day to urgent): passing little or no urine (the dry nappy for 12 hours, the adult passing almost nothing), dizziness or faintness standing, confusion, a sunken-eyed listless baby, blood in the vomit or stool, severe or localized abdominal pain, green (bile) vomiting, or the high fever with stiff neck. The ordinary three-day misery with fluids going down is home medicine. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
How long until we feel human again?
The shape is mercifully short: the violent phase (the vomiting, the diarrhea, the aching misery) runs 24-72 hours, with most people clearly improving by day two and eating normally by day three or four; the appetite and energy lag the stomach by a few days. The children bounce back faster than the adults, infuriatingly. The things that stretch it: the dehydration itself (the headache and the dizziness linger while the fluids lag: keep sipping through recovery), and the early return to rich food (let the appetite lead). If the vomiting is not clearly settling by day three, or the diarrhea runs past a week, that is the point for the GP rather than more waiting.
Why did the alcohol hand gel not protect us?
Because norovirus is built differently: it lacks the fatty outer envelope that alcohol gels dissolve (the mechanism that makes the gels work against flu and COVID), so it shrugs off the sanitizer, and the only reliable hand decontamination is mechanical: soap and water, a proper 20-second wash, physically lifting the virus off. The same hardiness drives the household rules: it survives on surfaces for days (the bleach-based cleaner is the one that kills it there), it aerosolizes from vomit (flush with the lid down, clean the bathroom after episodes, and the cleaner-up should wash hands obsessively), and it takes only a few particles to infect. The gels are not useless in life, but against this virus they are decoration.
Why the strict 48-hour rule for school and work?
Because the virus keeps shedding after the symptoms stop (you feel recovered but you are still contagious for about 48 hours, sometimes longer), and norovirus needs so few particles to infect that a symptom-free shedder with one hand-washing lapse re-seeds the classroom, the office kitchen, or the care home. The 48-hour rule (from the last episode of vomiting or diarrhea, not from feeling better) is the public-health firewall that breaks outbreaks, and the early return is the classic way families and schools get a second wave. For food handlers and healthcare workers the rule is stricter still. The boredom of day three at home is the price of not being the class's patient-zero-twice.
What should we actually eat and drink?
The modern guidance is gentler than the old rituals: the fluids are the medicine (small, frequent sips: water, diluted squash, or the rehydration sachets, which are worth having for the children and the frail because they replace the salts as well as the water), and the food is appetite-led (when hunger returns, eat what appeals: the toast-and-rice instinct is fine but not required, and there is no need for the old 24-hour starvation rules, which helped nobody). The things to skip: anti-diarrhea tablets for children (not recommended; adults can use them if essential but the bug is better out), anti-sickness tablets are a clinician's call for the child who cannot keep any fluid down, and the fatty blowout on day one of recovery. Little and often beats everything.
When is it more than the vomiting bug?
The deviation list, because most vomiting-and-diarrhea is exactly what it seems: the dehydration signs (no urine for 12 hours, the very dry mouth, the sunken eyes, the listlessness, the dizziness on standing: same-day help), blood in the vomit or the stool (urgent), green bile vomiting or severe localized abdominal pain (the surgical bellies, not the bug), the high fever with a stiff neck or a non-blanching rash (the meningitis alarm), the severe headache, and the symptoms not settling (vomiting past three days, diarrhea past a week, or weight dropping). The elderly and the babies tip into trouble faster and with less fanfare: lower thresholds for both. The ordinary course needs no one; the deviations need today.
Will we get it again?
Probably, eventually, and the immunity story explains why: norovirus infection gives short-lived, strain-specific protection (months, against that strain), while the virus circulates in many strains and keeps mutating, so a household can meet it again next winter, and a lifetime holds many episodes. The practical mitigation is not the immunity but the habits (the soap-and-water reflex, the bleach-cleaning of the sickroom, the 48-hour rule honored by your household and, ideally, everyone else's), plus the honest comfort: healthy children and adults weather it fine, and each episode is the same two-to-three-day shape. The vaccine question comes up every year: candidates are in trials, none is available yet, so the bleach bottle remains the household's best friend.