Hospital chiefs in Cornwall are drawing up a list of staff they can call on amid a big influx of flu patients.
Doctors and nurses are being asked to put their names forward at the Royal Cornwall Hospital.
It has been admitting up to 60 emergency medical cases a day since Monday, 25% more than usual.
Many patients have flu or other respiratory illnesses, said the hospital. It has been forced to reopen wards closed for the Christmas holiday.
A spokeswoman said: "We need a pool of people we can call upon so we are asking front-line staff such as doctors and nurses to volunteer their names for the next week or 10 days."
Director of nursing Christine Rashleigh said the hospital needed extra staff to cope with the work.
"The challenge is discharging enough patients to allow those other patients to come in the front door," she said.
"We are working very closely with the community hospitals and social care to free up as many acute beds as possible."
The hospital is advising people with flu-like symptoms to first contact the NHS Direct service and pharmacists.
It is also advising people to wash their hands to prevent the spread of flu.