Varenicline
"I loved Chantix the first time that I used it!  I told everyone how wonderful this drug was.  Unfortunatley, I started smoking again and decided to use the Chantix again.  Shortly after starting the Chantix, I experienced my first migraine.  It was so scary because it had neurological side effects as well. My vision was blurry and my left arm went numb.  I stopped the Chantix and called my family doctor.  She did a neuro exam on me and everything was okay.  I had an MRI which was negative.  I decided to try the Chantix again after not having another migraine.  Guess what.....my second migraine happened.  I was shocked since I had taken the drug before with no problems but now I am convinced that it was the Chantix that caused this."