Coronation Street star Charles Lawson has pulled out of another two performances of the Inspector Rebus stage play.
He is being replaced with understudy Neil McKinven for the matinee and evening performances at the King's Theatre today.
His departure means he will have been replaced for at least half the shows in the Edinburgh run of Long Shadows.
Lawson has not appeared on stage since appearing to forget his lines during the second half of the opening night performance on Monday.
The Northern Irishman apologised to the sold-out audience and said he was feeling faint before being helped off the stage.
The producers of the show, which premiered in Birmingham last month before its eagerly-awaited run in Edinburgh this week, say Lawson was "taken ill" during Monday's show.
Lawson, 59, who saw doctors on Tuesday morning, has not commented publicly on his absence from the production, the first time Ian Rankin's grizzled detective has been adapted for the stage.
A statement issued on behalf of the producers said: "Doctors have advised that Mr Lawson should not perform today and so Neil McKinven will perform the part of Rebus.
"Mr Lawson will be back on stage as soon as possible."
Lawson had been performing in a pivotal scene with John Stahl, who plays Rebus’s arch-nemesis Cafferty, and Cathy Tyson, who plays long-time the retired detective’s long-time sidekick Siobhan Clarke. McKinven took over the role of Rebus after a break of around five minutes.
The King’s Theatre was sold out for the opening night of the run of the play, which was created by Rankin, who was in the audience, and playwright Rona Munro.
It emerged last week that Andy Gray had pulled out of the forthcoming Christmas panto at the King’s Theatre after being diagnosed with blood cancer.
The 58-year-old had been due to appear with regular co-stars Grant Stott and Allan Stewart in Beauty and the Beast.