Originally Answered: Singing Emergency PLEASE HELP?
Drink plenty of water, small quantities often, bottled water is best as theres less impurities in it. Rest the voice, that means no whispering as this is the same as shouting to your vocal chords.
The water should help your vocal chords but more importantly will flush the toxins out of your system that the cold is making you produce. You'll pee a lot but thats normal, when its clear, youre getting somewhere (sorry for the description but thats true). Put simply your body is fighting the infection and the rubbish that is collecting in the process has to be got rid of.
The people above have suggested lemon/herbal tea, and some people swear by it, I personally prefer just plain water in emergency cases like this.
Your stuffed nose will usually clear with the adrenilin rush, you'll feel slightly bunged up, but the crowd probably wont notice.
If your still coughing due to a tickle in the throat go to your pharmicist in the morning and get a spray that is for speakers/singers etc, it usually soothes sore throats and stops tickles from making you cough.
Also youre going to have to pace your performance more than usual, get the crowd on your side, sing easier songs between the more challanging ones, if other members of your band can sing, get them doing more songs.
Finally spend a long time warming your voice tomorrow before you try to sing, its recovering and will take much longer to warm up, look after it and it will see you through.
However, despite all that, if the time comes and you really cant do it, DONT, better to lose this one than damage your voice forever.