Combining Zyban, the patch and nicotine gum is very effective.
Those great success rates for smokers who quit by the seventh week using Zyban get a power boost when combined with nicotine replacement therapy. A clinical trial showed that 58 percent of patients who used combination therapy had quit by week 7, as opposed to 36 percent in a separate trial who took Zyban alone [source: GlaxoSmithKline]. The manufacturer of the drug reports, however, that the study has not been replicated and should not be interpreted as demonstrating the superiority of one method of treatment over another.
However, a separate study by a researcher at the University of Wisconsin showed that patients who used Zyban, along with the long-acting patches and the occasional boost from nicotine gum, were most likely to quit.
Chantix has not been tested in combination with nicotine replacement therapy.
Also, it's important to remember that if you experience some side effects with one drug, you may multiply those side effects with three.