Hi, Champix contains varenicline that is used to help adults stop smoking. But like other medications this medication has some side effects of its own. This medication may very rarely affects the hormones of our body and cause diabetes mellitus. It may cause chest pain, tightness or discomfort. It also may cause frequent urination, especially in the night, tiredness, weakness, fatigue, dizziness, increased appetite, weight gain etc. These side effects are mild and usually go away over time as the body adjusts to this medication. But if these side effects persist for long or bother you then you should consult your prescribing doctor promptly for medical help. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Zubayer Alam, General And Family Physician,