Can Chantix During Chemo Therapy Cause Vomiting?

My son started on Chantix 2 weeks ago, then went in the hospital for a week of chemo treatments. The hospital did not give him the Chantix while he was in the hospital, but he resumed taking it when he got out. He will be out 2 weeks then go back in for another week long chemo session. Does this starting and stopping Chantix affect the drug s purpose? He is very sick, throwing up, while in the hospital and probably would throw up the Chantix even if they do give it to him. Should he just wait until the chemo treatments are over to use the Chantix or continue taking it when he can?