How long is norovirus contagious?

The illness itself usually lasts about two days. The catch: the CDC says you can still spread the virus for two weeks or more after you feel better.

That is why norovirus, the winter vomiting bug, is the one illness on this site where the clock runs from the end of symptoms, not the start. You will feel better long before you stop being infectious, and it takes only a few virus particles to pass it on. The NHS supplies the rules and the CDC the figures the NHS does not publish, and Britain, Germany, Italy and the Netherlands each count the clear days differently.

Day by day

UK & USA (NHS / CDC) does not publish a day-by-day contagious period for norovirus; its rule counts from the last episode of vomiting or diarrhoea instead.

Are you contagious before norovirus symptoms start?

Neither the NHS nor the CDC says you are. What they say is that the illness arrives fast: the CDC puts the time from exposure to symptoms at 12 to 48 hours, and says you are most contagious while you have symptoms. The NHS publishes no incubation figure. In practice the pre-symptom window barely exists, because the first symptom is often the first warning anyone gets.

Other European authorities give slightly different incubation ranges from the same literature: Germany's RKI 6 to 50 hours, the Dutch RIVM 8 to 60 hours with 30 as typical, Italy's ISS 12 to 48 hours, and France's Ameli 24 to 72 hours. None of them publishes a figure for contagiousness before symptoms either.

When is norovirus most contagious, and why does vomiting matter most?

The CDC is specific: you are most contagious while you have symptoms, especially vomiting, and during the first few days after you feel better. It takes only a few norovirus particles to make someone ill. The virus spreads through vomit and poo, on hands, on surfaces, in food handled by someone who has it, and in the droplets thrown into the air when someone vomits.

The NHS names the everyday routes: close contact with someone who has norovirus, touching surfaces or objects that have the virus on them and then your mouth, and eating food that has been prepared or handled by someone with it. A shared bathroom during the vomiting phase is the single riskiest place in the house, which is why the NHS cleaning list is toilet seats, flush handles, taps and bathroom door handles.

How long does norovirus last, and when does it stop being contagious?

The illness is short. The NHS says norovirus usually gets better in about two days and that you will usually start to feel better in two to three days; the CDC says most people are better within one to three days. Both count from the first symptom.

The contagious period is not. The NHS rule is two full days with no vomiting and no diarrhoea before you go back to work, school or nursery or visit anyone in hospital or a care home. The CDC goes further and says you can still spread norovirus for two weeks or more after you feel better. Germany's RKI puts the same point in numbers: the virus is usually still present in your poo for another seven to fourteen days after symptoms stop, which is why hand washing with soap stays important long after the 48 hours are up.

So a day of feeling fine is not the finish line. The finish line is two full days without symptoms, and even after that, your hands are the thing to watch.

Is there a test for norovirus?

Not one you can do at home. The CDC says diagnostic methods for norovirus detect viral genetic material or viral antigen, which means a sample sent to a laboratory, and the NHS norovirus page does not mention testing at all.

No test decides when you can go back. The NHS rule counts days since the last episode; a negative result would not shorten it, and a positive one, given that the CDC says you can still spread the virus for two weeks or more, would not tell you anything the rule does not already assume.

Treatment: nothing shortens the contagious period

There is no specific medicine to treat norovirus, the CDC says, and antibiotics will not help because they fight bacteria, not viruses. The treatment is fluids: drink plenty to replace what is lost, and the CDC says oral rehydration fluids from a pharmacy are most helpful for mild dehydration.

Because nothing treats the virus, nothing shortens the contagious period either. Anti-sickness or anti-diarrhoea medicines may make you feel better, but neither the NHS nor the CDC gives them any role in deciding when you are safe around others. The 48-hour count starts from your last symptom, medicated or not.

When can you go back to work, school or nursery after norovirus?

The NHS rule is clear and applies to everyone: do not go to school, nursery or work until you have not been sick or had diarrhoea for two days, and do not visit others in hospitals or places like care homes until the same two days have passed. The UK Health Security Agency's exclusion list for nurseries and schools says the same: away until two days after the diarrhoea and vomiting has stopped. The CDC gives the same figure for the two things that matter most, handling food and caring for others: wait at least two days, 48 hours, after symptoms stop.

This is one illness where the neighbours mostly agree, but not on who the rule is for. Germany's RKI applies the same 48 hours after symptoms stop to everyone. Italy's ISS asks food handlers to wait three days after recovery, because the virus stays in poo for at least 72 hours. The Dutch RIVM applies its rule, one day after symptoms stop, only to people who work with food or in care, and says keeping children off school during an outbreak is not justified because transmission has usually already happened. France's Ameli publishes no return rule; in Spain the Catalan health service, Canal Salut, asks for 48 hours without vomiting or diarrhoea before returning.

Everyday situations: a baby at home, a shared bathroom, cooking, the gym, a care home

Count full days from the last episode of vomiting or diarrhoea, not from when you started to feel better.

• A baby or an older relative at home: the NHS asks you to get advice if you are worried about a baby under 12 months with norovirus, and dehydration is the danger for the very young and the very old. If you have two bathrooms, give the person who is ill one to themselves, and wash your hands with soap before touching the baby or preparing anything they eat.
• A shared bathroom: the NHS cleaning list is toilet seats, flush handles, taps and bathroom door handles. The CDC adds that surfaces need a chlorine bleach solution of 1,000 to 5,000 parts per million, left on for at least five minutes.
• Cooking for the family: the CDC says do not prepare or handle food for at least two days, 48 hours, after symptoms stop. The NHS says wash your hands with soap and water before preparing, serving or eating food, and alcohol gel does not count.
• The gym: no NHS or CDC rule mentions gyms, but the NHS work rule, two days clear, is the sensible one, and the CDC's warning that a few particles are enough should keep you off shared equipment until then.
• A flight or a family dinner: the same two days clear. A dinner where you handle food falls under the CDC's 48-hour food rule; a dinner where someone else cooks still means shared surfaces, and the CDC's warning that the first few days after you feel better are among the most contagious.
• A care-home or hospital visit: the NHS is explicit. Do not visit anyone in hospital or a care home until you have had two days with no vomiting or diarrhoea.

How long is norovirus contagious in children, older adults and people with weakened immunity?

Neither the NHS nor the CDC publishes a longer contagious period for children, older adults or people with weakened immunity, and none of the European authorities in this comparison does either. The 48-hour rule is the same for a toddler and an adult. What differs is the danger to the person, not the danger from them: the NHS asks you to get advice if you are worried about a baby under 12 months, if a child stops feeding, or if there are signs of dehydration that do not improve with rehydration sachets.

Children are also the group most likely to pass it on, simply because nursery-age children vomit without warning and cannot manage their own hand washing. The NHS puts hand washing with soap and water after changing nappies on its list for exactly that reason. And the CDC notes that you can get norovirus many times in your life, because there are many different types, so a bout last winter protects no one.

Why the official guidance on norovirus differs between countries

On the biology there is no argument: a short, violent illness, then a long tail in which you can still pass the virus on. The RKI's seven to fourteen days in poo, the ISS's at least 72 hours and the CDC's two weeks or more all describe the same thing. The disagreement is about how much of that tail to turn into a rule, and for whom.

The UK and Germany apply 48 hours to everyone. Italy sets 72 hours, but only for food handlers. The Netherlands sets 24 hours, only for food and care workers, and argues that excluding schoolchildren during an outbreak is pointless because the class has already been exposed. France says nothing, and Spain's figure comes from Canal Salut, the Catalan health service, rather than the national ministry. Both the RIVM and the NHS have a point: one is minimising disruption where exclusion cannot help, the other is protecting hospitals and care homes, where an outbreak is serious.

If you are in the UK the NHS rule stands; if you live in Germany, Spain, Italy or the Netherlands, switch the calculator to your country and it applies that rule. If you work with food, in care or in a hospital, the two full days are the minimum, and the CDC's two weeks of possible spread is the reason to keep washing your hands with soap and water well beyond them.

What the guidance says in six countries

The same illness, six official positions. Where a country publishes nothing, the table says so rather than borrowing a neighbour's number.

How to stop norovirus spreading at home: soap, bleach and a 60°C wash

• Wash your hands with soap and water after going to the toilet or changing nappies and before preparing, serving or eating food. The NHS says alcohol hand gels do not kill norovirus, and the CDC says hand sanitiser does not work well against it and is not a substitute for washing for at least 20 seconds.
• Wash clothes and bedding with vomit or poo on them on a 60°C wash and separately from other laundry, the NHS says. The CDC's version: detergent and hot water on the longest cycle, then tumble dry on the highest heat.
• Clean toilet seats, flush handles, taps and bathroom door handles, as the NHS advises. The CDC specifies a chlorine bleach solution of 1,000 to 5,000 parts per million, or a disinfectant registered as effective against norovirus, left on the surface for at least five minutes.
• Do not prepare or handle food for others, or care for others, until at least 48 hours after symptoms stop, the CDC says.
• Stay away from work, school, nursery, hospitals and care homes until two full days after your last episode of vomiting or diarrhoea, the NHS rule.

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Other illnesses

Contagious periods for the other illnesses covered by this tool.

This tool gives general information based on published guidance. It does not diagnose you and does not replace advice from a doctor who knows your situation. You choose the illness; we do not work out what you have.