Singing live with a cold is quite a stressful experience but it can be done without it being a disaster.

Concentrate on your breathing - make sure you get that air into your diaphragm (stomach area) and use it to hold your notes.

As Mike said, watch out for side effects of drugs; basically, don't take anything you haven't taken before and you aren't 100% confident about.

Drink plenty of fluids - water is the best, not coffee or alcohol! So carry a bottle of water with you and drink plenty from it during soundcheck etc

And don't forget to explain to your audience you have a cold; get them on your side but sharing a few anecdotes about your cold.

I once saw Marianne Faithfull with the worst cold i've ever seen anyone on stage with. She had to blow her nose between each song and phlegm was coming out as well. But she managed to deliver a great performance nonetheless. So good luck smile

Nat JM - quirky post punk music. New video for "chirpy wheels" just added