The 75-year-old royal was recently treated for an enlarged prostate.
The Princess of Wales was recently hospitalized for planned abdominal surgery.
This will likely be Charles' longest period away from work.
The Princess of Wales is 'making good progress' as she recovers at home, according to Kensington Palace.
The Duke of Sussex's ongoing rift with his family didn't stop him from reaching out amid their health scares.
A source tells ET that the king was admitted to London Clinic on Friday morning.
Kate Middleton and the king are both currently hospitalized at London Clinic.
The Duke of Sussex had sued over an article about his publicly funded security arrangements.
Prince William drove himself to the hospital to support wife Kate after she underwent abdominal surgery.
The mother of three is recovering after undergoing abdominal surgery.
The Prince of Wales has already canceled several of his events to be by his wife's side.
Royal expert Katie Nicholl talks with ET about Kate Middleton’s hospitalization and King Charles’ prostate condition.
Kensington Palace announced that Kate Middleton is recovering from abdominal surgery on Wednesday.
The monarch has postponed a series of meetings and events, per doctor's orders.
