What Is Norwalk Virus?

  • Arunima BabuMasters, Biomedical Sciences, University of Aberdeen, UK
  • Katheeja Imani MRes Biochemistry, University of Nottingham, UK


Norovirus, previously known as Norwalk virus, is a highly contagious virus that causes vomiting and diarrhoea. It is often called the ‘winter vomiting bug’ or stomach flu and it can be very unpleasant but symptoms usually go away after a few days.1

Outbreaks of norovirus are very common and can occur at any time but most often occur from November to April in the countries located above the equator and from April to September in the countries below the equator. This article will detail the symptoms of this contagious virus and guide you on how you can prevent it as well as easily treat it at home.

Causes of Norwalk virus

Norovirus is a highly contagious virus which means that it can be easily spread to others. The virus enters your body, making your stomach and intestines swollen or inflamed. This is a condition known as gastroenteritis which triggers symptoms of norovirus.

Norovirus is present in vomit and stools and can spread from the first day you have symptoms until several days after you recover. This virus is hard to kill as it can withstand both hot and cold temperatures as well as disinfectants. Therefore, virus particles can remain on surfaces and objects for days or even weeks.

You may get the norovirus infection by:

  • Being in close contact with someone with the virus
  • Eating contaminated food or drinking contaminated water
  • Touching a contaminated surface or object and then touching your mouth or nose

Signs and symptoms of Norwalk virus

Norovirus symptoms often begin within one or two days of being infected and usually last one to three days. Some people may not show symptoms of norovirus infection but can still be contagious and therefore can still spread the virus to others.

The main symptoms of norovirus virus are:

  • Feeling sick/nauseous
  • Diarrhoea
  • Vomiting
  • Headaches
  • Fever
  • Weak or aching arms and legs
  • Stomach pain or cramps

Infected children and adults usually experience similar symptoms except in cases of diarrhoea or vomiting. Vomiting is seen more often in children than in adults and diarrhoea is seen more often in adults than in children.

Diagnosis of Norwalk virus

The diagnosis of norovirus depends on the symptoms you experience but it can also be diagnosed using your stool sample.

Further tests are only required if you have an underlying medical condition that weakens your immune system and affects your body’s ability to fight infections.

Management and treatment for Norwalk virus

Norovirus is usually treated at home and most people recover completely without treatment. However, young children, older adults or people with medical conditions may experience severe dehydration from vomiting and diarrhoea and so may require medical attention and treatment.

Recovery and treatment depend on the health of your immune system. The most important thing is to ensure you are well-rested and hydrated.

In general, you can treat norovirus by:

  • Staying hydrated by drinking plenty of fluids and taking small sips if you feel sick
  • Get plenty of rest
  • Eating soft and bland food

If your symptoms are severe, health professionals might recommend:

  • Oral rehydration sachets to replace lost fluids and prevent dehydration
  • Medicine to stop severe diarrhoea for a few hours


Can the Norwalk virus be prevented?

To prevent norovirus infection you can:

  • Avoid contaminated food and drinks, especially food prepared by someone who is infected
  • Wash your hands often with soap and water for at least 20 seconds
  • Wash fruit and vegetables before eating it
  • Cook your food thoroughly (especially seafood) or to an appropriate temperature
  • Avoid contact with people who are infected with the virus
  • Disinfect objects or surfaces that may have been contaminated
  • Use caution if travelling to an area with a high risk of norovirus infection – for example, only eat cooked food, drink only hot or carbonated drinks and avoid street food

Who is at risk of the Norwalk virus?

Anyone can be infected with norovirus as it is highly contagious and so is easily spread to others. However, you are at a higher risk of norovirus if:

  • You have come into contact with someone who is infected with norovirus
  • You have a genetic susceptibility which means your genes make you more likely to develop symptoms 

How common is the Norwalk virus?

Norovirus is an extremely common virus. Globally, there are around 685 million cases reported each year with 200 million of those cases affecting children.

Is the Norwalk virus contagious?

Norovirus is highly contagious and can be easily spread to others through close contact with an infected person or through contaminated food, surfaces or objects.

When should I see a doctor?

You should seek medical attention if:

  • You are unable to eat or drink, this can lead to severe dehydration
  • You have bloody diarrhoea or are bleeding from the bottom
  • You have diarrhoea for more than 7 days or are vomiting for more than 2 days
  • You are worried about a baby that is under 12 months

You should seek urgent medical attention if:

  • You are vomiting blood or your vomit looks like ground coffee
  • Your vomit is green or yellow-green
  • You have a sudden, severe stomach ache or headache


Norovirus also known as Norfolk virus is a highly contagious virus that causes vomiting and diarrhoea. It affects both children and adults and can easily spread through close contact and touching contaminated food, objects or surfaces. Norovirus is usually diagnosed based on the symptoms which are usually vomiting, diarrhoea, nausea, headache and muscle aches. Treatment includes staying hydrated and drinking plenty of fluids, staying well rested and eating soft, bland food when you can. Your symptoms should start to go away after 2 days but if your symptoms persist or if you are unable to eat or drink or you have bloody diarrhoea or vomit, please seek medical attention immediately.


  1. Robilotti E, Deresinski S, Pinsky BA. Norovirus. Clin Microbiol Rev [Internet]. 2015 Jan [cited 2023 Mar 10];28(1):134–64. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4284304/
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Suad Mussa

Bachelor of Science – BSc, Biology. Queen Mary University of London

Suad Mussa is a biology graduate with a strong passion for medical writing and educating the public about health and wellbeing.

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