Gary Lucy was taken ill on stage during his "The Full Monty" performance on Friday (22.03.19).
The "Hollyoaks" actor passed out 10 minutes into the production at the Liverpool Empire theatre, and his fellow stars had to help him off stage, after he was struck down with tonsillitis and a chest infection.
A theatre source said: "It was quite dramatic and it seemed like Gary was pretty unwell.
"Audience members were understandably quite worried, there were audible gasps in the room."
Gary - who is taking a break from his "Hollyoaks" role as Luke Morgan to star in the play - took a few days off as a result.
A spokeswoman for Gary told The Sun newspaper's Bizarre column: "He is pretty poorly with tonsillitis and a chest infection so has had to take a couple of days off work with medication."
The 37-year-old actor took to his Twitter account to post a picture of his tonsils and admitted he couldn't talk but was hopeful he would be available for last night's (25.03.19) show in Leeds.
He wrote: "That's a throat btw Can't talk but will be fighting fit for Monday in Leeds @FullMontyPlay (sic)"
Gary inadvertently caused another stir at the Liverpool Empire earlier this month when the theatre received "several complaints" about a poster of his bare butt.
The Empire were hit with criticism for displaying a large image of his naked behind, advertising his part in "The Full Monty" play, but the former "Footballers" Wives" star saw the funny side.
He wrote on Twitter: "LIVERPOOL !!! A big juicy thank you from my A**e ! @FullMontyPlay will see all you a week on Monday where you'll see more than my A**e (sic)"