Prescription Medications to Quit Smoking: Varenicline, Bupropion, and More

Prescription cessation medications are significantly more effective than OTC NRT for most heavy smokers. Despite this, they're underused — partly because of lingering concerns about side effects that have been substantially resolved by large-scale safety studies.

Here's a rigorous comparison of the main options.

Varenicline (Champix / Chantix)

Varenicline is the most effective single pharmacological agent for smoking cessation, with the strongest evidence base of any cessation medication.

How It Works

Varenicline is a partial agonist at the alpha-4 beta-2 nicotinic acetylcholine receptor — the primary receptor subtype responsible for nicotine addiction. It works by two simultaneous mechanisms:

1. Partial agonism: It partially activates the receptor, providing enough stimulation to reduce withdrawal symptoms and craving without producing the full reinforcing effect of nicotine
2. Competitive antagonism: It blocks the receptor from nicotine binding, so if you do smoke while taking it, nicotine produces a significantly reduced reward

The result: cravings are reduced and the reinforcing effect of smoking is blunted simultaneously.

Effectiveness

• 12-month continuous abstinence: Approximately 20–25% (vs. 8–12% for single NRT, 3–5% for unassisted)
• Versus placebo: Odds ratio approximately 2.5–3.0
• Versus NRT: Varenicline outperforms nicotine patch in head-to-head trials (OR approximately 1.5)
• Combination varenicline + NRT: Emerging evidence suggests adding NRT to varenicline produces further benefit (OR ~1.2–1.3 additional)

Dosing

Standard protocol:

• Weeks 1–3: Start varenicline 1–2 weeks before quit date
  • Days 1–3: 0.5 mg once daily
  • Days 4–7: 0.5 mg twice daily
  • Day 8 onward: 1 mg twice daily
• Quit smoking on day 8–14
• Continue for 12 weeks total

An extended course of 24 weeks is sometimes used for high-dependence smokers and produces further improvement in long-term abstinence. For a day-by-day view of what to expect during treatment, see our quit smoking timeline.

Side Effects

The most common: nausea (occurring in about 30% of users), usually mild and often resolves within 1–2 weeks. Taking with food and a full glass of water significantly reduces this. Vivid or unusual dreams.

The psychiatric safety controversy: Early post-marketing data raised concerns about neuropsychiatric adverse events (depression, suicidality, aggression). Subsequent large-scale studies — particularly the EAGLES trial (>8000 participants) — found no significant increase in psychiatric adverse events compared to nicotine patch or placebo, even in people with pre-existing psychiatric conditions. The FDA removed its black-box warning in 2016. Current guidance supports use in patients with psychiatric conditions with appropriate monitoring.

When to be cautious: Severe renal impairment requires dose adjustment. Discuss with GP if significant psychiatric history.

Access

Prescription only. Available on NHS (England) — up to 12 weeks prescribed free through Stop Smoking Services. Many private health insurers cover it. Direct cost: approximately £40–90 per course out of pocket depending on country.

Bupropion (Zyban / Wellbutrin)

Bupropion was originally developed as an antidepressant and was found incidentally to reduce smoking rates in patients. It was subsequently tested and licensed as a cessation aid.

How It Works

Bupropion inhibits reuptake of dopamine and norepinephrine, increasing both in the synapse. It also has weak nicotinic receptor antagonist properties. The net effect is partially compensating for the dopamine deficit of nicotine withdrawal while also reducing the rewarding effect of smoking.

Effectiveness

• 12-month abstinence: Approximately 15–20%
• Versus placebo: Odds ratio approximately 1.9
• Versus varenicline: Bupropion is somewhat less effective than varenicline in direct comparisons

Bupropion is a reasonable choice for people who cannot take varenicline or who have depression alongside the quit attempt (as it treats both simultaneously).

Dosing

• Start 1–2 weeks before quit date
• 150 mg once daily for 3 days, then 150 mg twice daily
• Continue for 7–12 weeks

Side Effects

Most common: dry mouth, insomnia, headache. The insomnia is particularly notable — taking the second dose mid-afternoon rather than evening helps.

Contraindications: History of seizures is a contraindication (bupropion lowers seizure threshold). Bulimia or anorexia nervosa (also contraindicated). Current or recent MAOI use.

Access

Prescription required. NHS prescribes it via GP. Insurance coverage varies.

Cytisine (Cytisimicine / Tabex)

Cytisine is a plant-derived alkaloid (from Laburnum anagyroides seeds) that has been used in Eastern Europe for cessation since the 1960s. It works similarly to varenicline — partial agonism at nicotinic receptors.

Effectiveness: Two large randomized trials show cytisine is significantly more effective than placebo and comparable to NRT, with some evidence it may approach varenicline's efficacy.

Availability: Widely available OTC in Eastern Europe (branded as Tabex). Available via prescription in several countries. Not currently licensed in the US or UK, though this is evolving.

Side effects: Similar to varenicline — nausea, sleep disturbances. Generally well tolerated.

Advantage: Cost — a full course of cytisine costs a fraction of varenicline and may be more accessible globally.

Comparing the Options

How to Get a Prescription

UK: GP or NHS Stop Smoking Service. NHS covers up to 12 weeks of varenicline or bupropion through Stop Smoking Services.

Australia: Both medications are PBS-listed and subsidized.

US: Check with your insurer — many plans cover cessation medications. Free medication may be available through state quitlines.

EU: Availability and coverage varies by country; varenicline is widely available.

FAQ

What is the most effective medication to quit smoking?

Varenicline (Champix/Chantix) has the strongest evidence base, with 12-month quit rates approximately double those of NRT alone. Combination of varenicline with NRT produces the highest rates in current trials.

Is Champix safe?

Yes, for the vast majority of people. The large EAGLES trial (8000+ participants including people with psychiatric conditions) found no significant increase in neuropsychiatric adverse events compared to placebo or nicotine patch. The earlier FDA black box warning was removed in 2016.

How long should I take varenicline?

The standard course is 12 weeks. A 24-week course produces additional benefit in some high-dependence smokers. Do not stop early if still experiencing cravings — completing the course significantly improves long-term outcomes.

Related: Nicotine Replacement Therapy Guide, Nicotine Patches vs. Gum, Quit Smoking Tips That Actually Work