A hospital has closed its doors to visitors in a bid to stem the growing number of people infected with the winter vomiting bug.
Birmingham City Hospital has told visitors to stay away after it was forced to close three wards due to the norovirus infection.
Other hospitals have also taken to Twitter to caution visitors and potential patients.
Doncaster and Bassetlaw Hospitals NHS Foundation Trust tweeted: "Please don't visit hospital until at least 2 days after last symptoms of #vomiting #diarrhoea 'norovirus Stay home, rest & take fluids."
Recent figures from the Health Protection Agency (HPA) show that more than 750,000 people could be affected by the outbreak of norovirus that has swept the UK.
There have been 2,630 confirmed reports of norovirus so far this season, but for every reported case there are likely to be a further 288 unreported sufferers, the HPA said.
It means 757,440 people could be affected by the stomach bug - representing a 72 per cent increase on the same period last year.
The infection has led to the closure of dozens of hospital wards.
A statement from Sandwell and West Birmingham Hospitals NHS Trust, which runs City Hospital, reads: "City Hospital has closed three wards due to the infection, and as a precaution has closed all wards at City Hospital to visiting, effective immediately.
"However, this does not affect the following areas: critical care, paediatrics, maternity and the Birmingham & Midland Eye Centre.
"Members of the public are urged not to come to accident and emergency departments if they have diarrhoea and vomiting symptoms, unless they need emergency medical treatment. Instead, they should telephone their GP or NHS Direct on 0845 4647.
"People suffering with symptoms who are due to attend the hospital for an appointment should telephone the hospital first."
Norovirus is highly contagious and can be transmitted through contact with an infected person or contaminated surfaces and objects. It is known to spread rapidly in closed environments such as hospitals, schools and nursing homes.
Symptoms include sudden vomiting, diarrhoea or both, a temperature, headache and stomach cramps.
The bug usually goes away within a few days.
Although people can suffer from norovirus at any time of the year, activity increases in the winter months, with most cases seen between October and April.