King Charles III is headed to his country estate in Western England on Friday after he was hospitalized due to side effects of a scheduled cancer treatment the day prior.

The king had to cancel his scheduled events Thursday and Friday due to temporary side effects he experienced after a cancer treatment.

“Following scheduled and ongoing medical treatment for cancer this morning, the king experienced temporary side effects that required a short period of observation in hospital,” Buckingham Palace said in a statement. “His majesty’s afternoon engagements were therefore postponed.”

It is not clear what kind of side effects Charles experienced, according to The Associated Press.

Charles, 76, was diagnosed with cancer last year and it is unspecified what kind he has. 

He began treatment in February of 2024.