Varenicline
"I have been smoking for 15 years, I can still remember the day I started I'm 26 now smoke a pack every 2 - 3 days. A  year and a half ago I wanted to quit smoking so I started champix. A week in I started to get little cravings by 3 months I was totally finished smoking no cravings or anything. So I decided to not take the rest of the 3 months I had left, I kept getting the awful nausea all day even if I took it on a full stomach. I figured "I already quit, I don't need the rest". Didn't smoke for 2 months after that. Was smoke free for 5 months, then I started smoking again its been a year  I've smoked again. But I started taking it again so hopefully I can hold out. Pretty much what I'm saying is stay on for the full program or its not gonna work."