The Queen is being treated in hospital for gastroenteritis, an infection of the stomach and large intestine.
The two most common causes of the illness in adults in England are the norovirus and food poisoning, according to the NHS. Common symptoms include vomiting, diarrhoea and dehydration.
It is not yet known if the Queen is suffering from viral or bacterial gastroenteritis but it is unlikely she is being given antibiotics as this prolongs the time it takes to settle the condition.
More top news
Emergency services rushed to the scene to douse the flames, but there were no immediate reports of casualties.
A motion to remove John Bercow from his position as Speaker of the House of Commons is struggling to find support.
Familial hypercholesterolaemia causes abnormally high levels of cholesterol, increasing the risk of a heart attack at a young age.