For instant use prior to a performance, try Vocalzones pastilles (as originally made for Enrico Caruso, as it used to say on the box)
Not particularly tasty, but bearable, and they really can work wonders on a cold night when your voice isn't at its best - and the black tongue makes a fascinating conversation piece.
They became difficult to get for a period, but we still manage thought our local Boots Chemists, though there have been occasions when they had to order them
VOCALZONES
Jim Carroll