Chantix does not appear to have any significant interactions with most drugs. However, there may be an increase in side effects, such as skin reactions, when used with nicotine replacement therapy (NRT) because they both activate nicotine receptors in the brain.
Zyban, on the other hand, does not have additive effects with NRT. Taking Zyban with NRT has the same potential side effects as each drug alone, but there is no increased risk of side effects of either drug.
This information is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment, and should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.