Varenicline, sold under the brand names Chantix and Champix among others, is a medication used for smoking cessation[5][7] and for the treatment of dry eye syndrome.

[5][6] When activated, this receptor leads to the release of dopamine in the nucleus accumbens, the brain's reward center, thereby reducing cravings and withdrawal symptoms with smoking cessation, although less pronounced than a full agonist (e.g.

[9] Common side effects include nausea, insomnia, abnormal dreams, headache, and nasopharyngitis (inflammation of the nose and throat).

[17][18] Mild nausea is the most common side effect and is seen in approximately 30% of people taking varenicline, though this rarely (<3%) results in discontinuation of the medication.

Rare side effects reported by people taking varenicline compared to placebo include change in taste, vomiting, abdominal pain, flatulence, and constipation.

[17][18] No evidence for increased risks of cardiovascular events, depression, or self-harm with varenicline versus nicotine replacement therapy was found in one post-marketing surveillance study.

[41][42] Use of Cytisus plants as a smoking substitute during World War II[43] led to use as a cessation aid in eastern Europe and extraction of cytisine.

[7] In September 2021, Pfizer announced a recall of "all lots of its anti-smoking treatment, Chantix [Varenicline], due to high levels of cancer-causing agents called nitrosamines in the pills".

[54] According to the Pfizer Inc. 2020 Form 10-K Annual Report, high-revenue products by the company include[d] Chantix/Champix (varenicline) to treat nicotine addiction, which recorded direct product revenues of more than $1 billion in 2019, $919 million in 2020, and $398 million in 2021 (the lower 2021 revenue was due, in part, to the basic product patent expiration for Chantix in the US in November 2020 and in Europe in September 2021, and the aforementioned Pfizer voluntary recall across multiple markets and a global pause in shipments of Chantix).

[55][56] In October 2021, the US FDA approved Oyster Point Pharma to market Tyrvaya as a new route of varenicline administration through nasal spray for the treatment of dry eye disease.