About 28 million American adults smoke, roughly 15 million try to quit each year, and most try without any of the medicines proven to help. That is partly a trust problem: the best known quit drug carried a black box warning for years, and the newest candidate was supposed to be approved this summer and was not. This article sets out what the large trials actually found about each option, what happened with cytisinicline, and what researchers are testing next.
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What counts as a smoking cessation medication
The FDA has approved seven products for quitting smoking, in three groups. Nicotine replacement therapy, or NRT, gives the body nicotine without smoke: the patch, gum, lozenge, inhaler, and nasal spray. Bupropion, sold as Zyban for smoking and Wellbutrin for depression, is a non nicotine pill. And varenicline, long sold as Chantix and now mostly available as a generic, is a pill that partly activates the brain's nicotine receptors while blocking nicotine from fully doing so. Nothing new has joined this list since varenicline in 2006.
Two facts from the research frame everything below. First, all of these roughly double a person's chance of quitting compared with willpower alone, and combining a medicine with counseling, even a single quitline call, roughly doubles the effect again. Second, most people who quit do it after several attempts, and each attempt with the right support is more likely to be the last one. The trials are how we know which support is right.
Does Chantix work? What the biggest trial found
Yes, and it is the most effective single medicine we have. The evidence comes from EAGLES, a trial of 8,144 people who smoked, run across 16 countries and published in 2016, which compared varenicline, bupropion, the nicotine patch, and placebo head to head over 12 weeks of treatment. Participants were randomly assigned, and neither they nor their doctors knew who was taking what, a design called double blind. The outcome that matters most, staying smoke free from week 9 through week 24, was 21.8 percent with varenicline, 16.2 percent with bupropion, 15.7 percent with the patch, and 9.4 percent with placebo.
Two things are worth noticing in those numbers. Varenicline more than doubled the placebo rate and clearly beat both other medicines. And even the best option left about 4 in 5 people still smoking at six months, which is why researchers keep looking and why quitting usually takes more than one try. In real world US data, quit rates for every option run lower than in the trial, because trial participants get structured support that most people never receive.
Chantix side effects, and the warning that was removed
This is where the trust problem comes from. In 2009 the FDA added a boxed warning to varenicline, its most serious type, about reports of mood changes, agitation, and suicidal thoughts. EAGLES was designed specifically to answer that question, and it enrolled thousands of people with and without a history of psychiatric illness. The result: varenicline did not increase serious neuropsychiatric side effects compared with placebo or the nicotine patch, in either group. In December 2016 the FDA removed the boxed warning. The common side effects are real but mostly mild: nausea in about a quarter to a third of people, vivid dreams, trouble sleeping, and headache, and they usually fade after the first weeks.
A second scare followed. In 2021 Pfizer recalled Chantix worldwide after finding a nitrosamine impurity, a class of chemical that can raise cancer risk with long exposure, above acceptable limits. The recall caused shortages for about two years. Generic varenicline meeting current limits is now widely available in the US, and the FDA considers the benefit of quitting smoking to far outweigh the small theoretical risk from the impurity at the levels found. If you were prescribed Chantix before 2021 and stopped, the medicine you would get today is the same molecule from different manufacturers.
Chantix vs Wellbutrin: how the two pills compare
Both are non nicotine pills, and EAGLES compared them directly: 21.8 percent versus 16.2 percent smoke free at six months, a clear edge for varenicline. Bupropion, the medicine in Wellbutrin and Zyban, is still a good choice for some people, particularly those who also have depression, want to avoid weight gain, or cannot tolerate varenicline's nausea. It carries its own cautions, including a small seizure risk that makes it unsuitable for people with seizure disorders or eating disorders. Neither pill contains nicotine, and both are usually started a week or two before the quit date so that the medicine is working when the last cigarette is smoked.
Nicotine patches and the combination most people never try
The nicotine patch is the most familiar quit aid and the most searched, and it works: in EAGLES it beat placebo handily. But the strongest evidence for NRT is not for the patch alone. A 2023 Cochrane review of more than 100 trials found that combining a patch, which gives steady background nicotine, with a fast acting form such as gum or a lozenge for cravings, raises quit rates about 27 percent above either alone, with high certainty. This combination NRT is what most guidelines now recommend as the first line non prescription option, and it is available over the counter. Starting the patch before the quit date, and using NRT for longer than the standard 8 to 12 weeks, both also improve results in trials.
Cytisinicline: two positive trials, then a wall
Cytisinicline is a plant based compound that works like varenicline on the same brain receptors. A version of it has been sold in Central and Eastern Europe for decades, but it was never tested to US standards until recently. Then it was, twice. In ORCA-2, published in JAMA in 2023, 810 adults who smoked were randomly assigned to cytisinicline or placebo, everyone got behavioral support, and quitting was verified with a lab test. In the 12 week treatment group, about a third were smoke free during the last four weeks of treatment, versus 7 percent on placebo, and 21 percent were still smoke free at six months versus 5 percent. ORCA-3, a replication in 792 people published in 2025, found almost exactly the same thing: 30.3 percent versus 9.4 percent at the end of treatment, and 20.5 percent versus 4.2 percent at six months. Side effects were mild, mostly some nausea and sleep disturbance, and fewer people stopped the medicine for side effects than in varenicline trials. An indirect comparison published in 2026 found no significant difference in quit rates at the end of treatment, but by six months cytisinicline showed significantly higher odds of sustained abstinence than varenicline.
The FDA accepted the application in September 2025 and set a decision date of June 20, 2026. It would have been the first new quit smoking medicine in 20 years. Instead the agency issued a complete response letter, a decision that declines approval for now and specifies what more it needs. The letter cited manufacturing deficiencies at a third-party facility and incomplete labeling, not concerns about the drug's efficacy or safety, and the company planned to resubmit late in 2026. For the millions who tried varenicline and could not tolerate it, this delay matters, and cytisinicline's separate program for quitting vaping, where nothing at all is approved, is still moving.
What researchers are testing next
The field's frustration with a 20 year drought has produced an unusually varied pipeline, much of it recruiting now. Some studies aim to make existing medicines work better rather than replace them. One trial combines varenicline with nicotine lozenges and a smartphone app that reminds people to take the medicine, testing whether the problem with varenicline is the drug or how consistently people take it. Another is studying how cytisinicline changes brain responses to cigarette cues, using imaging to understand why it works.
Others come from outside the field entirely. GLP-1 medicines, the class that includes tirzepatide, reduce the reward value of many things, and observational data suggested people taking them smoke less; a multi site trial of tirzepatide for smoking cessation is now testing that directly. A separate study is testing whether targeting brain receptors called NMDA and sigma-1, involved in craving and stress, can help people quit. Brain stimulation, financial incentives, and quitting programs built into cancer, lung, and heart clinics are all under study. And because most people who try to quit never see a specialist, several trials test whether text messages, pharmacists, or primary care visits can deliver what the trials show works.
Two studies recruiting now
A trial of varenicline combined with nicotine lozenges and a smartphone medication support app tests whether pairing the most effective pill with fast acting NRT and a reminder tool raises quit rates, in adults who smoke daily. A multi site trial of tirzepatide for smoking cessation tests whether a GLP-1 medicine can help adults quit, one of the first controlled tests of this idea. Both, along with the cytisinicline imaging study and the NMDA and sigma-1 trial, are listed with eligibility and locations on our smoking cessation studies page. Study medicines and quit support are typically provided at no cost as part of a clinical trial, and joining does not require leaving your own doctor.
Common questions
What is the most effective smoking cessation medication? Varenicline, based on the largest head to head trial: 21.8 percent of people were smoke free at six months versus 16.2 percent with bupropion, 15.7 percent with the patch, and 9.4 percent with placebo. Combination nicotine replacement, a patch plus gum or lozenge, is the strongest over the counter option. Adding counseling to any of them roughly doubles the effect.
Is Chantix still available? Brand name Chantix has been largely off the market since Pfizer's 2021 recall over a nitrosamine impurity, but generic varenicline that meets current limits is widely available by prescription in the US. It is the same medicine.
Is cytisinicline approved? Not as of mid 2026. It passed two Phase 3 trials in the US, and the FDA was due to decide by June 20, 2026, but issued a complete response letter instead. The company planned to resubmit late in 2026. It remains available only in clinical trials in the US, including studies recruiting now.
Can you use nicotine patches and varenicline together? Some studies suggest the combination helps people who could not quit on varenicline alone, and it is being tested directly in a trial recruiting now. Whether to combine them is a decision for a prescribing clinician, since it depends on how much you smoke and how you respond.
How long do you take quit smoking medication? Standard courses are 8 to 12 weeks for varenicline, bupropion, and nicotine replacement, though trials show longer use, up to six months, improves results for some people and is safe. Many clinicians extend treatment for people who have relapsed after shorter courses before.
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