Quick answer: Norovirus is a highly contagious stomach bug that causes sudden vomiting and diarrhoea. It spreads through contact with an infected person, contaminated food, water, or surfaces. Symptoms usually start 12 to 48 hours after exposure and last 1 to 3 days. The best way to stop it spreading is washing your hands with soap and water — hand sanitiser alone does not kill it.
Nobody enjoys talking about vomiting and diarrhoea, but when norovirus hits your home, school, or workplace, knowing the facts saves you a lot of trouble. This guide breaks it down in plain language, with no medical jargon, so you know exactly what you are dealing with.
What Is Norovirus?
Norovirus is a virus that causes infection of the stomach and intestines. These viruses are also referred to as viral gastroenteritis, though they are commonly known as the stomach bug or stomach flu, despite being unrelated to influenza. Norovirus is the leading cause of gastroenteritis in the United States and is among the most contagious viruses known. The ingestion of a few viral particles is sufficient to cause an infection.
According to the CDC, there are on average 2500 norovirus outbreaks in the United States annually, with most occurring between November and April, which is why it is also called the winter vomiting disease. However, it can occur at any time of the year.
Common Norovirus Symptoms
Quick answer: The main symptoms are sudden vomiting, watery diarrhoea, nausea, and stomach cramps. Some people also get a mild fever, headache, or body aches.
Norovirus does not creep up slowly. It tends to hit fast and hard. The most common signs include:
- Sudden, often forceful vomiting
- Watery diarrhoea
- Stomach cramps or pain
- Nausea
- A low-grade fever
- Headache and body aches
Symptoms usually appear 12 to 48 hours after you pick up the virus, and most healthy adults feel better within one to three days. That said, you can still carry and spread the virus for up to two weeks after you feel fine again, so it pays to stay careful even once the worst has passed.
Children, older adults, and anyone with a weaker immune system can become dehydrated quickly. Watch out for a dry mouth, dizziness, dark-coloured urine, or not urinating much — these are signs the body needs fluids urgently.
How Does Norovirus Spread?
Quick answer: Norovirus spreads through direct contact with an infected person, contaminated food or water, and touching contaminated surfaces before touching your mouth.
This virus is sneaky because it spreads in several ways at once:
- Person to person — caring for someone who is ill, sharing food or cutlery, or simply being in close contact with them.
- Contaminated food — especially raw or undercooked shellfish, or food handled by someone who did not wash their hands properly. Cooking does not always kill it, because the virus can survive temperatures up to around 145°F (63°C).
- Contaminated water — untreated water from wells, lakes, or swimming pools.
- Surfaces and objects — door handles, taps, toilet seats, and toys can carry the virus for days, sometimes even weeks, if they are not cleaned properly.
Places where people live or eat close together — cruise ships, schools, nursing homes, and restaurants — are classic hotspots for outbreaks, simply because the virus has more chances to jump from person to person.
How Long Does Norovirus Last on Surfaces?
This is one of the trickiest parts of norovirus: it is tough. It can survive on hard surfaces for days, and in some conditions, for weeks. It also shrugs off freezing temperatures, so putting contaminated food in the freezer will not make it safe.
How to Prevent Norovirus
Quick answer: Wash your hands with soap and water for at least 20 seconds, clean surfaces with a bleach-based disinfectant, stay home while you are ill, and avoid preparing food for others for at least 48 hours after symptoms stop.
1. Wash your hands properly — and often
This is the single most effective step you can take. Use soap and warm running water, and scrub for at least 20 seconds — about as long as singing “Happy Birthday” twice. Do this:
- After using the toilet or changing a nappy
- Before eating, cooking, or handling food
- After caring for someone who is unwell
Here is the part that surprises most people: hand sanitiser does not work well against norovirus. The virus has a tough outer shell that alcohol struggles to break down, so sanitiser should only ever be a backup when soap and water are not available, never a replacement.
2. Clean and disinfect properly
Ordinary cleaning sprays often are not strong enough. The CDC recommends a bleach-based disinfectant for surfaces that may be contaminated, left on the area for at least five minutes before wiping it away.
3. Handle food safely
Wash fruit and vegetables thoroughly, cook shellfish properly, and avoid preparing food for others if you have been unwell in the last two days. Anyone who is sick should steer clear of the kitchen until they are symptom-free.
4. Stay home when you are ill
It feels obvious, but it is the step people skip most often. Staying off work, school, or childcare while you have symptoms — and for 48 hours afterwards — is one of the best ways to stop an outbreak spreading further.
5. Wash laundry carefully
If clothing or bedding has been in contact with vomit or diarrhoea, handle it with gloves, avoid shaking it (this can spread virus particles into the air), and wash it on a hot cycle.
When to See a Doctor
Most people recover from norovirus at home with rest and plenty of fluids. However, you should get medical help if you notice:
- Signs of dehydration, such as dizziness, a very dry mouth, or little to no urination
- Blood in vomit or stool
- Symptoms lasting more than a few days
- A very young child, elderly person, or someone with an existing health condition becoming unwell
Frequently Asked Questions
Is norovirus the same as food poisoning?
Not quite. They share similar symptoms and can both spread through food, but norovirus is a specific virus, while food poisoning can be caused by several different germs or toxins.
Can you build immunity to norovirus?
Only partial and short-term. There are many different strains, so getting ill once does not fully protect you from catching it again later.
Does cooking food kill norovirus?
Not always. The virus can survive some cooking temperatures, so good hygiene while preparing food matters just as much as cooking it thoroughly.
How long should I stay away from others?
At least 48 hours after your symptoms fully stop, since you remain contagious during that time.
Helpful Resources
- CDC — About Norovirus — https://www.cdc.gov/norovirus/about/index.html
- CDC — How to Prevent Norovirus — https://www.cdc.gov/norovirus/prevention/index.html
- NHS — Norovirus (Vomiting Bug) — https://www.nhs.uk/conditions/norovirus/
- FoodSafety.gov — Bacteria and Viruses (Norovirus) — https://www.foodsafety.gov/food-poisoning/bacteria-and-viruses#norovirus
This article is for general information only and is not a substitute for medical advice. If you are worried about your symptoms, speak to a doctor or healthcare provider.
