Varenicline (trade name Chantix and Champix) is a medication used for smoking cessation. Varenicline is also used for the treatment of dry eye disease.

The most common side-effects include nausea (feeling sick), insomnia (difficulty sleeping), abnormal dreams, headache and nasopharyngitis (inflammation of the nose and throat).

It is a high-affinity partial agonist for nAChRα4β2, a subtype of nicotinic acetylcholine receptor (nAChR) that leads to the release of the neurotransmitter dopamine in the nucleus accumbens (reward center of the brain) when activated, and therefore, has the capacity to reduce the feelings of craving and withdrawal caused by smoking cessation. In this respect it is similar to cytisine and different from the nicotinic antagonist bupropion and nicotine replacement therapies (NRTs) like nicotine patches and nicotine gum. It is estimated that varenicline successfully helps one of every eleven people who smoke remain abstinent from tobacco at six months.