The first sign of norovirus is usually a sudden sick feeling followed by forceful vomiting and watery diarrhoea.
Some people may also have:
- a raised temperature (over 38C/100.4F)
- headaches
- stomach cramps
- aching limbs
Symptoms usually appear one to two days after you become infected but they can start sooner. Most people make a full recovery within a couple of days.
Apart from the risk of dehydration, the illness is not generally dangerous and there are usually no long-lasting effects from having norovirus. However, it can be pretty unpleasant while you have it.
Dehydration
The main risk from norovirus is dehydration from your body losing water and salts from vomiting and diarrhoea.
The first sign of dehydration is thirst. Other symptoms are:
- dizziness or lightheadedness
- headache
- tiredness
- dry mouth, lips and eyes
- dark, concentrated urine
- passing only small amounts of urine (fewer than three or four times a day)
Mild dehydration is common and can be easily reversed by making sure you have plenty to drink.
Dehydration is more of a risk in the very young and the elderly. It's important that you get medical attention straight away if you think your child is becoming dehydrated.
Severe dehydration
If you do not replace the lost fluid, dehydration will get worse and could lead to complications such as low blood pressure and kidney failure. It can even be fatal.
As well as severe thirst, you may also have:
- dry, wrinkled skin
- an inability to urinate
- irritability
- sunken eyes
- a weak pulse
- a rapid heartbeat
- cold hands and feet
- seizures
If you or your child have any symptoms of severe dehydration after catching a norovirus infection, seek medical attention as soon as possible.
Read more about treating norovirus.
