Chantix contains verenicline, which is effective in treating addiction for smoking by acting on nicotine receptors. It does not have any significant interactions with Ortho Tri Cyclen Lo, which is a combined low dose oral contraceptive pill. So, taking Chantix concomitantly with Ortho Tri Cyclen Lo will not affect the birth control and does not decrease its efficacy. Both drugs can cause common side effects like nausea, vomiting, head aches while Chantix can cause neuropsychiatric problems like mood disorders and aggression.
Smoking should be stopped if you have been taking Ortho Tri Cyclen Lo. But, Chantix is not recommended for you as its safety and efficacy is not established in people below 18 years of age. So, I advise you to consult your physician for alternative treatments like various nicotine replacement products like Nicoderm, Nicorette etc.
Thank you and do get back for any further queries.