Merton misses 'Have I Got News' with illness
The comedian and team captain, 51, is suffering from a kidney infection. Stand-up comic Frank Skinner will replace him on the topical panel show.
"Paul loves filming the show and really tried to avoid taking the day off," a source told The Sun.
"It's only a minor infection but he was too sick to film the show. Luckily, Frank stepped in and Paul was able to stay home and get some rest."
Merton stood down from the show during its eleventh series in 1996, but returned afterwards claiming it had been given a "shot in the arm" in his absence.