The tenor was due to join forces with gender-bending 2014 Eurovision Song Contest winner Wurst for the Pop meets Opera show on 17 May (15). Peruvian singer Juan Diego Florez has now been drafted in as his replacement.
Officials at the Vienna State Opera have not disclosed the nature of Domingo's ailment, but his poor health has also prompted the veteran star to postpone his performances at the venue's five-day production of Giuseppe Verdi's Nabucco from Sunday (10May15).
He is expected to be back onstage at the Vienna State Opera from 18 May (15).
It's the second time Domingo has fallen ill in as many months - in early April (15), a bad cold forced the 74 year old to step down from a gig at New York's Metropolitan Opera. Fellow opera star Luca Salsi was called upon to fill in for the star for a performance of Verdi's Ernani.