Beloved TV personality Ed McMahon's health issues are much worse than he's admitted to the public - he's in hospital battling both bone cancer and pneumonia.

The former The Tonight Show sidekick, 85, is in a "serious" condition in an intensive care unit after he was admitted to an undisclosed facility almost four weeks ago.

His representative Howard Bragman confirmed on Friday that McMahon is being treated for pneumonia in hospital, but it has now emerged that he has also been fighting systemic bone cancer.

A source tells news show Entertainment Tonight that McMahon's wife, Pam, has been holding a bedside vigil, and her "deep faith is helping her through this difficult time".

(This news article provided by World Entertainment News Network)