New Year, no cigarettes: varenicline vs bupropion

Medically reviewed by Muhammad A Jalil, Superintendent Pharmacist (GPhC Reg No: 2236161)

Published 2026-08-22 · Clinically reviewed 2026-08-22 · Updated 2026-08-23

Varenicline and bupropion are the UK's two prescription stop-smoking tablets. How they compare on effectiveness, side effects and who suits each.

Varenicline is the more effective of the two prescription stop-smoking tablets: in the largest head-to-head trial, about one in three people taking it were smoke-free through the final weeks of treatment, against roughly one in four on bupropion — and both comfortably beat patches or willpower alone. Bupropion earns its place when varenicline is unsuitable, has been tried already, or when post-quit weight gain is a major worry, since it measurably blunts that gain. Whichever you choose, the tablets start one to two weeks before a fixed quit date — for a New Year attempt, that means starting between Christmas and the first days of January.

How each tablet works

Varenicline is a partial agonist at the brain's main nicotine receptor. It occupies the receptor and stimulates it gently — taking the edge off craving and withdrawal — while blocking nicotine itself from landing, so a lapse cigarette feels oddly pointless. Bupropion came from antidepressant research: it raises dopamine and noradrenaline signalling, which softens the withdrawal dip in mood and concentration. It has nothing to do with nicotine receptors, which is why it can be paired with patches under supervision.

What the numbers say

The EAGLES trial randomised more than 8,000 smokers across varenicline, bupropion, nicotine patches and placebo. Through the final month of the twelve-week course, continuous abstinence ran at roughly 34% for varenicline, 23% for bupropion, 23% for patches and 12% for placebo; six months on, varenicline still led. The same trial settled an older safety worry: rates of serious mood or behaviour side effects were not meaningfully higher on either tablet than on placebo, including in people with stable mental health conditions — which is why UK guidance treats varenicline as a first-line option again now that supply has returned.

Side effects, compared

Varenicline's signature effects are nausea (much reduced by taking it with food and a full glass of water), vivid dreams and disturbed sleep. Bupropion's are dry mouth, insomnia (take the second dose in the afternoon, not at bedtime) and, rarely, seizures — about one in a thousand — which is why it is avoided in anyone with a seizure history, a current or past eating disorder, or heavy drinking that might involve sudden alcohol withdrawal. Bupropion also interacts with more medicines, including some antidepressants and tamoxifen, so the prescribing questionnaire matters.

Who suits which tablet

Most people without contraindications start with varenicline on effectiveness grounds. Bupropion is the better fit when varenicline caused intolerable nausea or sleep disruption on a previous attempt, when your other medicines clash with it, or when weight is the deal-breaker: trials consistently show smaller post-quit weight gain on bupropion while treatment continues. Neither tablet is used in pregnancy — specialist support plus nicotine replacement is the route there. And if tablets are off the table entirely, combination nicotine replacement (a patch plus gum or spray) used properly is a respectable third option.

Timing a New Year quit properly

Pick a specific quit date — the first Monday back at work is popular — and count back one to two weeks for the prescription start. With varenicline you smoke as normal through the first week while the dose builds over eight days, which removes the cliff-edge feeling from day one. Courses run twelve weeks for varenicline and seven to nine for bupropion, and finishing the course matters: stopping at week four roughly doubles the relapse risk. Line up behavioural support too — even brief weekly contact roughly doubles any medicine's success rate, and combining a tablet with support is the strongest evidence-backed package there is.

Frequently asked questions

Can varenicline and bupropion be taken together?

The combination has been studied, but the gains were modest and side effects rose, so it is not routine UK practice. Combining bupropion with nicotine patches is done occasionally under supervision.

I smoked after my quit date — is the attempt ruined?

No. A lapse in the first weeks is common and predicts nothing by itself, particularly on varenicline, which strips most of the reward from the cigarette. Keep taking the tablets and recommit to the next smoke-free day.

Isn't varenicline the drug that was withdrawn?

The branded product (Champix) was withdrawn in 2021 over a manufacturing impurity, not because the medicine stopped working or became unsafe at doing its job. Generic varenicline returned to UK prescribing once the impurity issue was resolved, and national guidance recommends it again.

What about vaping instead of tablets?

Vaping is an evidence-supported quitting tool in the UK and suits people who want a hand-to-mouth substitute. Tablets suit people who want to break the ritual entirely. Success rates are broadly comparable; the best method is the one you will actually follow for three months.

Do the tablets work without willpower?

They stack the odds; they do not quit for you. Both medicines roughly double or triple your chances compared with going it alone, and combining tablets with structured support — a local stop-smoking service, an app, or weekly check-ins — raises the odds again. Plan for cravings to cluster around weeks two and six, and treat coffee, alcohol and the after-meal pause as rehearsed danger zones rather than ambushes.

A quit attempt with the right medicine and a fixed date is the strongest position a smoker can start January from. You can check your eligibility for stop smoking treatment online, and a UK clinician will confirm which tablet fits your history.