I agree with Padgett that not drinking enough water can harm your voice. I don't know about alcohol "tightening the vocal cords" but it does lead to dehydration. (As Archie Bunker said, "You don't buy beer, you rent it" -- and you pay interest, too.) I had to leave a band because the gigs were in very smoky pubs, and I have asthma. Zinc lozenges can be helpful for an irritated throat...but make sure you take them on a full stomach, otherwise you may get an uncomfortable "sick" feeling in your stomach a while later. The best advice is as recommended above: avoid smoke. There is no magic cure.

Aloha,
Mark