Britain's King Charles spent a short time under observation in hospital on Thursday after experiencing side effects from treatment for cancer, Buckingham Palace said.
The king has been having treatment for the illness since he was diagnosed with an unspecified form of cancer in February last year following tests after a corrective procedure for an enlarged prostate.
The Palace said he had returned to his home Clarence House, and that as a precaution his engagements for Friday would be rescheduled.