Norovirus season is starting. In the US, norovirus outbreaks are most common from November to April, according to the Centers for Disease Control and Prevention (CDC), and the NHS calls it the winter vomiting bug, although you can catch it at any time of year. This page sums up what the NHS and CDC say about symptoms, care at home and stopping it spreading. It is general information, not medical advice: if you are worried about yourself or someone you care for, ask a doctor, nurse or pharmacist.
What norovirus is
Norovirus is a very contagious virus that inflames the stomach and intestines. It is sometimes called “stomach flu,” but it is not related to influenza. The CDC says it is the leading cause of vomiting, diarrhea and foodborne illness in the US, with 19 to 21 million illnesses, about 109,000 hospital stays and about 900 deaths each year, mostly among adults aged 65 and over. There are many types of norovirus, so having it once does not stop you getting it again.
Symptoms and how long they last
Symptoms usually start 12 to 48 hours after exposure, the CDC says, and the NHS notes that they tend to come on suddenly. The main ones are:
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- feeling sick (nausea)
- vomiting
- diarrhea
- stomach pain
Some people also get a high temperature, a headache and aching limbs. Most people feel better within one to three days.
How it spreads
The virus spreads through close contact with someone who has it, by touching contaminated surfaces and then your mouth, and through food or drink that has been contaminated. Raw or undercooked shellfish such as oysters can also carry it. The CDC adds that the virus can be in vomit or stool before symptoms start and can stay in stool for two weeks or more after a person feels better, which is why it moves so quickly through homes, schools and care homes.
Looking after yourself at home
There is no specific medicine for norovirus, and antibiotics do not work against viruses. Care at home is about rest and fluids:
- Drink plenty of fluids, in small sips if you feel sick. The NHS suggests water or squash and advises avoiding fruit juice and fizzy drinks, which can make diarrhea worse.
- Oral rehydration solutions, sold at pharmacies, help most with mild dehydration, according to the CDC.
- Eat when you feel able, and avoid fatty or spicy food.
- Keep breastfeeding or bottle feeding babies, offering smaller feeds more often if they are being sick. Do not make formula weaker than usual.
- Paracetamol can ease discomfort; check the leaflet before giving it to a child. The NHS says not to give anti-diarrhea medicine to children under 12 or aspirin to children under 16.
Our guide to how much fluid to drink each day covers everyday hydration once you are well again.
Signs of dehydration
The CDC lists passing less urine, a dry mouth and throat, and feeling dizzy when standing up. In children, watch for crying with few or no tears and unusual sleepiness or fussiness. The NHS adds dark, strong-smelling urine as a sign.
When to get medical help
The NHS advises calling 111 in the UK, or contacting a doctor elsewhere, if:
- you are worried about a baby under 12 months, or a child stops feeding
- a child under 5 shows signs of dehydration, such as fewer wet nappies (diapers)
- you keep being sick and cannot keep fluids down
- there is blood in the diarrhea
- diarrhea lasts more than 7 days or vomiting lasts more than 2 days
Get emergency help for vomiting blood, a stiff neck with pain from bright light, a sudden severe headache or stomach ache, confusion, or trouble breathing. Severe dehydration may need fluids given through a drip in hospital.
Young children, older adults and people with weakened immune systems are more likely to become seriously ill, so seek advice early for them.
Stopping it spreading
- Wash hands with soap and water for at least 20 seconds, especially after using the toilet or changing nappies and before handling food. Alcohol hand gels do not kill norovirus, the NHS says; the CDC says sanitizer can add to handwashing but not replace it.
- Clean up carefully. The CDC advises wearing gloves, wiping up with paper towels, then disinfecting with a bleach solution of 5 to 25 tablespoons of household bleach (5% to 8%) per gallon of water, or an EPA-registered disinfectant labelled for norovirus. Leave it for at least 5 minutes, then clean again with soap and hot water.
- Wash laundry hot. Handle soiled items with gloves and without shaking them. The NHS suggests washing at 60°C, separately from other laundry; the CDC advises the longest hot cycle and drying on high heat.
- Stay home. The NHS says to stay off work, school or nursery, and not to visit hospitals or care homes, until you have had no vomiting or diarrhea for 2 days. The CDC likewise advises waiting at least 48 hours after symptoms stop before preparing food or caring for others.
- Cook shellfish thoroughly, to at least 145°F (63°C), as quick steaming may not kill the virus.
Sources
- NHS: Norovirus (vomiting bug)
- CDC: About Norovirus
- CDC: How to Prevent Norovirus
- CDC: Norovirus Facts and Stats
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