The 75-year-old has generally enjoyed good health, other than an array of sporting injuries as a younger man.
In 2008, he had a non-cancerous growth removed from the bridge of his nose in a minor, routine procedure and in 2003 had a hernia operation.
He has had Covid-19 twice, but had only mild symptoms and continued to work through it.
On Friday morning, he was admitted to the London Clinic for treatment for an enlarged prostate. The Queen was with him for company, and he is understood to have visited the Princess of Wales, who is at the same hospital, before his surgery.
Then, a spokesman for Buckingham Palace said: “The King was this morning admitted to a London hospital for scheduled treatment.
“His Majesty would like to thank all those who have sent their good wishes over the past week and is delighted to learn that his diagnosis is having a positive impact on public health awareness.”
The Princess had been recuperating at the London Clinic after undergoing abdominal surgery at the hospital last week, and was discharged
The King received his diagnosis nearly two weeks ago, approving a statement about it from Buckingham Palace to give the public details of his condition in the hopes of raising awareness of its symptoms.
A press release was issued just 90 minutes after Kensington Palace confirmed that the Princess of Wales had undergone abdominal surgery at The London Clinic.
On Wednesday, January 17, a spokesman for the King said: “In common with thousands of men each year, The King has sought treatment for an enlarged prostate.
“His Majesty’s condition is benign and he will attend hospital next week for a corrective procedure. The King’s public engagements will be postponed for a short period of recuperation.”
At the time, the King was at his Scottish residence at Birkhall and had cancelled a handful of engagements as a result of advice from doctors. He has since been in Sandringham and Clarence House, as he awaited hospital treatment.
The Queen is said to have urged her husband, who is 75, to slow down. He in turn is said to be “raring” to return to work following a short period of recuperation.
After his diagnosis, the Queen said the King was “fine” and “looking forward to getting back to work”. She has visited at five times, understood to want to keep him company while he recuperates in hospital.
The King’s decision to share details of his medical condition led to a surge in the public seeking information about enlarged prostates.
NHS England said that since Charles shared his diagnosis, the “enlarged prostate” page on the NHS website has received 26,170 visits in 48 hours, including another 9,760 visits on Thursday, compared with a daily average of 1,400 visits earlier in the week.
Prostate Cancer UK saw 8,025 visits to its online risk check service, of which 6,800 were noted as high risk, more than double the previous day.