Norovirus: How Long It Lasts and How Long You Are Contagious

Norovirus has a reputation for good reason. It is the most common cause of infectious gastroenteritis in the UK, it takes remarkably few virus particles to infect someone and it is spectacularly good at spreading through households, schools, cruise ships, care homes and hospital wards. The illness itself is usually short. The problem is how efficiently it moves from person to person and how much of that happens after the worst has passed.

What norovirus does

Symptoms usually begin suddenly, twelve to forty-eight hours after exposure. The classic combination is being sick and having diarrhoea, often both, frequently starting with a wave of nausea that gives very little warning. Many people also have stomach cramps, aching limbs, a headache and a mild fever, which is why it is sometimes mistaken for flu. The vomiting can be forceful and repeated and that is the feature that makes norovirus so transmissible, since vomiting sprays the virus into the air and onto surfaces around it.

The illness typically lasts one to three days. Most healthy adults recover without needing to see anyone and the main risk during it is dehydration rather than the infection itself. That risk rises sharply in babies, very young children, older adults and anyone with a condition that makes fluid loss dangerous.

How long you are contagious

This is the part people get wrong and it is the reason outbreaks keep going. You are infectious from the moment symptoms start and remain so for at least forty-eight hours after they stop. You can also shed the virus in your stool for two weeks or more after you feel completely well, at declining levels.

The practical rule in the UK is clear and worth following even when you feel fine: stay away from work, school or nursery until forty-eight hours after your last episode of vomiting or diarrhoea. For anyone who works in healthcare, food handling or a care setting, this is not simply advice, it is how outbreaks in those settings are prevented. Going back at twenty-four hours because the symptoms stopped is the single most common way norovirus gets into a workplace or a ward. Avoid visiting hospitals or care homes for the same forty-eight hours and do not prepare food for other people during that window.

Why hand gel does not work

Alcohol-based hand sanitiser is effective against many viruses, including influenza and the virus that causes COVID-19, because those viruses have a fatty outer envelope that alcohol disrupts. Norovirus has no envelope. It is a tough, non-enveloped virus and alcohol gel is poor at inactivating it. Relying on hand gel during a norovirus outbreak gives a false sense of security.

What does work is soap and water, thoroughly, for twenty seconds, with attention to the physical action of scrubbing and rinsing, which removes the virus rather than trying to kill it in place. This is one of the few situations where the distinction between washing and sanitising genuinely changes the outcome.

Surfaces need the same thinking. Ordinary household cleaners are not reliably effective against norovirus. A bleach-based product, or a dilute bleach solution, is the recommended approach for cleaning up after someone has been sick and for wiping down toilets, flush handles, taps, door handles and light switches. Norovirus can survive on hard surfaces for days.

Looking after yourself

There is no treatment that shortens norovirus. It is a matter of getting through it while staying hydrated. Sip fluids frequently rather than drinking large amounts at once, which tends to come straight back up. Water is fine and oral rehydration sachets from a pharmacy are genuinely useful if you are losing a lot of fluid, because they replace salts as well as water. Avoid fruit juice and fizzy drinks, which can make diarrhoea worse.

Eat when you feel able, starting with something plain. The old advice to starve for a day has been abandoned, since there is no benefit to it. Anti-diarrhoeal medicines such as loperamide are not recommended for children and are best avoided generally in an infection like this, though a pharmacist can advise an adult on whether they are appropriate. Paracetamol will help with aches and fever.

Watch for dehydration rather than the vomiting itself. Dark urine or passing very little, dizziness on standing, a dry mouth, headache and unusual tiredness are the signs. In a baby, look for fewer wet nappies, a sunken soft spot on the head, no tears when crying and drowsiness. Our guide to gastrointestinal symptoms in viral illness covers the overlap with other infections.

Stopping it spreading at home

Once norovirus is in a household, containing it takes deliberate effort. Clean up any vomit or diarrhoea immediately, wearing disposable gloves if you have them, using paper towels that go straight in the bin and then a bleach-based cleaner on the area. Do not vacuum it, since that disperses the virus. Wash contaminated bedding and clothing separately on the hottest wash the fabric allows and do not shake it out first.

Keep the unwell person's towels and flannels separate. Where you have more than one bathroom, dedicate one to them. Wash hands with soap and water after any contact and before handling food. If you are the one who is ill, do not cook for anyone else. These measures sound excessive for a two-day illness and they are exactly what stops it becoming a two-week relay through everyone in the house.

Norovirus, food poisoning and other stomach bugs

Norovirus is often called food poisoning and sometimes it is: contaminated oysters, salad and raspberries are recognised sources and an infected food handler can contaminate a dish directly. But most norovirus is passed person to person rather than through food, which is why an outbreak follows social contact rather than a single meal.

Bacterial causes such as campylobacter, salmonella and E. coli tend to have a longer incubation, more often produce bloody diarrhoea and a higher fever and can last longer than three days. Rotavirus is a major cause in young children, though far less so in the UK since routine infant vaccination. As a rule of thumb, a sudden two-day illness dominated by vomiting that several people in a group develop within a day or two of each other is far more likely to be norovirus than anything you ate.

Is there a vaccine?

Not currently. Several candidates are in development and some have reached advanced trials, but there is no norovirus vaccine in routine use in the UK. Immunity after infection is partial and short-lived and there are many genetically distinct strains, so catching it one winter offers little protection the next. Hygiene remains the only reliable defence, which is a frustrating answer but an accurate one.

When to get medical help

Contact NHS 111 or your GP if you cannot keep any fluids down for a day, if there is blood in your stool, if you have severe stomach pain, if symptoms last more than three days in an adult or two in a child, if you have signs of dehydration that are not improving, or if you have a condition or medication that makes dehydration dangerous, such as kidney disease or diuretics. Be particularly quick to seek advice for a baby under a year old, an older adult or someone who is immunosuppressed. A pharmacist can help with rehydration before it gets to that point and knowing which NHS service to use saves time when you feel too ill to work it out.

A quick recap

Norovirus arrives suddenly twelve to forty-eight hours after exposure, usually lasts one to three days and needs fluids rather than treatment. You stay infectious for at least forty-eight hours after symptoms stop, which is the rule that decides when you can return to work or school. Alcohol hand gel does not reliably work on it, so use soap and water and bleach-based cleaners. There is no vaccine and reinfection is normal.

Frequently asked questions

How long after norovirus can I go back to work?

Forty-eight hours after your last episode of vomiting or diarrhoea, even if you feel well sooner. This is particularly important for healthcare, care home and food handling roles.

Does hand sanitiser kill norovirus?

Not reliably. Norovirus has no fatty envelope for alcohol to disrupt, so soap and water for twenty seconds is markedly more effective.

How long does norovirus survive on surfaces?

It can remain infectious on hard surfaces for days. A bleach-based cleaner is recommended rather than an ordinary household spray.

Can you catch norovirus twice in one winter?

Yes. Immunity is short-lived and there are many distinct strains, so catching it again in the same season is possible.

Is norovirus the same as food poisoning?

It can be spread by contaminated food, but most cases pass directly from person to person. Bacterial food poisoning usually has a longer incubation and can last longer.

Should I take something to stop the diarrhoea?

Generally no and not in children. Ask a pharmacist if you are an adult considering it. Rehydration is the priority rather than suppressing symptoms.

Is there a test for norovirus?

Stool testing exists and is used to confirm outbreaks in hospitals and care homes. It is not routine for individual cases, since it would not change treatment.