I had a lot of withdrawal symptoms before I went on Zyban too. You will see that after your second day, you will be smoking a cig, and all of a sudden, you will just want to stop it. It works really fast. It seems like they just make you lose interest in smoking!
Good luck!

I hope you are doing well in your efforts to quit!

Not doing as well as I would like. I've been taking Zyban for two weeks now and haven't been able to quit completely, though my smoking is cut by about half. The dry mouth really does make smoking unpleasant, but I just find myself drinking more fluids. I guess I just need to keep trying, some people say it take a few weeks to work while others have results in just days. I haven't wanted to do this, but I may have to resort to taking the Xanax the doc prescribed for the nighttime anxiety I get after not smoking all day. That might be the only way to get over the hump.