The Queen has been hospitalised for gastroenteritis, but though the condition is common, most people are unlikely to need hospital treatment.
Gastroenteritis sounds scary but it's really just the umbrella term for when the stomach or large intestine gets inflamed by an infection.
Caused by norovirus or food poisoning, symptoms are vomiting and diarrhoea and three or more episodes of either within 24 hours is classed as gastroenteritis rather than just an upset tummy.
Gastroenteritis is particularly common over the winter when people's immune systems may be lowered and when we're more likely to be in closer contact with others in confined spaces, such as on public transport, to get out of the cold.
[Related: Five spices that can boost your health]
Gastroenteritis becomes dangerous when there is the threat of serious dehydration, so it's important to make sure you're drinking plenty of fluids and re hydration liquids might be necessary.
More dangerous for children and the elderly, gastroenteritis can sometimes to hospitalisation, as in the case of the Queen, who is 86.This is usually due to dehydration and patients may need to be put on a drip to replace lost fluids.
How to avoid stomach infections
The main thing to remember is simply sticking to good hygiene practices such as regularly washing your hands and keeping food preparation areas clean using antibacterial products.
But picking up nasty bugs is sometimes unavoidable, in public places and around others. If you know someone with the infection, try to stay away as much as possible.
[Related: Is what you drink enough to harm your health]
If you come down with the bug and even once you're better you may still be harbouring germs. So make sure you wash your hands regularly, don't share any towels or bedding and stay off work for a good 48 hours after your toilet habits return to normal.
Though in some cases gastroenteritis can be very serious, most people make a full recovery within a few days.