King undergoes hospital observation due to cancer treatment side-effects

King Charles required hospital observation on Thursday after experiencing “temporary side-effects” as part of his continuing medical treatment for cancer, Buckingham Palace has said.

The 76-year-old monarch underwent scheduled treatment for cancer on Thursday morning, which required “a short period of observation in hospital”, according to a palace statement.

“His majesty’s afternoon engagements were therefore postponed,” a spokesperson said.

“His majesty has now returned to Clarence House and as a precautionary measure, acting on medical advice, tomorrow’s diary programme will also be rescheduled.”

The king sent his apologies to “all those who may be inconvenienced or disappointed” as a result of his decision to postpone his engagements and reschedule his diary, the statement added.

A source described it as a “most minor bump in a road that is very much heading in the right direction”.

Charles was diagnosed with an undisclosed form of cancer in February 2024 and returned to public-facing duties in April while still undergoing weekly treatment.

He has had a busy week of engagements, including a reception for media and a visit to a soil exhibition, and he is due to make a historic state visit to Italy in 10 days’ time. It is understood that this visit, where the king plans to become the first British sovereign to address both houses of the Italian parliament, is expected to go ahead as planned.

The king had been due to meet ambassadors in audiences at Buckingham Palace on Thursday afternoon and to travel to Birmingham on Friday, but these were postponed.

The king visited the London Clinic, the same hospital where he was treated for an enlarged prostate in January 2024, on Thursday morning.

It is understood the side-effects, the specifics of which have not been disclosed, were temporary and not uncommon with many medical treatments.

He was not joined by the queen during his brief stay, and travelled to and from the hospital by car.

After he returned home to Clarence House, the king was said to be on good form, and was reported to be working on state papers and making calls from his study.

A Buckingham Palace spokesperson said: “His majesty was due to receive credentials from the ambassadors of three different nations this afternoon.

“Tomorrow he was due to undertake four public engagements in Birmingham, and is greatly disappointed to be missing them on this occasion.

“He very much hopes that they can [be] rescheduled in due course and offers his deepest apologies to all those who had worked so hard to make the planned visit possible.”

The announcement from the palace was made late on Thursday evening because the king needed time to consult his staff and medical team after he returned to Clarence House.

Since his diagnosis last year, the king’s diary of engagements is understood to have been developed in full consultation with his medical team at all stages to protect his recovery.

It was decided on balance that it was wiser to cancel the visit to Birmingham, which involved four back-to-back engagements, as a precautionary measure.

Sources told PA Media the hospital visit was not a major development and no further updates were expected on the king’s health, with any minor alterations to his diary that may be required next week being announced in due course.

Charles became king on 8 September 2022 after the death of his mother, Queen Elizabeth II.

When announcing his cancer diagnosis last February, the palace asked for privacy and only confirmed it was a “form of cancer”.

The king was diagnosed after a “separate issue of concern was noted” and investigated while he was being treated for a benign prostate condition.

In December 2024, the palace said the king’s “treatment has been moving in a positive direction and as a managed condition the treatment cycle will continue into next year”.

When asked how he was that month during a visit with the queen to Walthamstow in north-east London, the king smiled as he replied: “I’m still alive.”