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

Stop-smoking medicines raise your chances of quitting — by around half for NRT and bupropion, and more than double for varenicline — yet many people never ask for them — partly because of old worries about side effects that a large trial has since answered. This page compares the main options using the Cochrane reviews and the official product information. Doses are there so you know what to expect; your prescriber sets yours.

Varenicline (formerly Champix / Chantix)

In the Cochrane review, varenicline more than doubled quit rates compared with placebo (RR 2.32, high-certainty evidence). It also beat bupropion (RR 1.36) and a single form of nicotine replacement (RR 1.25). Against combination NRT (patch plus a fast-acting form) there was no clear difference.

How It Works

Varenicline is a partial agonist at the α4β2 nicotinic receptor — the main receptor involved in nicotine addiction. It does two things at once:

1. Partial activation: it stimulates the receptor enough to ease cravings and withdrawal
2. Blocking: it occupies the receptor, so if you do smoke, nicotine has less effect

The NHS describes it simply: varenicline blocks nicotine's effects in your brain, making smoking less enjoyable and reducing cravings.

Dosing (US product information)

• You set a quit date and start the tablets one week before it — or start, and quit between days 8 and 35
• Days 1–3: 0.5 mg once daily
• Days 4–7: 0.5 mg twice daily
• Day 8 to the end of treatment: 1 mg twice daily
• Take after eating, with a full glass of water
• A course is 12 weeks; for people who have stopped by then, the label recommends another 12 weeks to improve the chance of staying stopped
• People with severe kidney disease take a lower dose

Side Effects

The product information lists nausea as the most common side effect — up to 30% of people — usually mild or moderate and often short-lived, though for some it lasts months. Starting on the low dose and building up helps. Sleep problems and unusual dreams are also common.

Mental-health safety: Early reports raised concerns about depression, agitation and suicidal thoughts. The EAGLES trial of 8,144 smokers, about half with a psychiatric history, found no significant increase in moderate or severe neuropsychiatric side effects from varenicline or bupropion compared with nicotine patches or placebo. In 2016 the US Food and Drug Administration removed its boxed warning, while noting that the risk of these side effects "is still present, especially in those currently being treated for mental illnesses". If you have a mental-health condition, you can usually still take it — tell your doctor, and stop and seek help straight away if your mood, behaviour or thinking changes.

Access

Prescription only. In England, your GP or local Stop Smoking Service can provide it; the NHS says varenicline is available again in the UK. Cost and coverage vary by country.

Bupropion (Zyban)

Bupropion was first an antidepressant. In the Cochrane review it raised quit rates by about 60% compared with placebo (RR 1.60). It worked about as well as a single form of NRT, and less well than varenicline or combination NRT.

How It Works

The NHS says bupropion works by changing chemicals in your brain to reduce cravings and withdrawal symptoms.

Dosing (UK product information)

• Start while still smoking, and set a stop date in the first two weeks of treatment — preferably the second week
• 150 mg once daily for six days, then 150 mg twice daily from day seven, at least 8 hours apart (US labelling uses three days before the increase)
• The maximum is 300 mg a day

Side Effects and Who Shouldn't Take It

The UK product information lists insomnia as very common; avoiding a bedtime dose helps. At the maximum dose, the risk of a seizure is about 0.1% (1 in 1,000).

It must not be used by people with: a current seizure disorder or any history of seizures; a brain tumour; a current or past eating disorder (bulimia or anorexia); a history of bipolar disorder; severe liver cirrhosis; anyone going through abrupt withdrawal from alcohol or benzodiazepines; anyone taking, or within 14 days of stopping, an MAOI antidepressant; or anyone already taking another medicine that contains bupropion. It also interacts with several other medicines — your prescriber needs your full medicine list.

Access

Prescription required, through your GP or Stop Smoking Service in the UK. Coverage varies elsewhere.

Cytisine

Cytisine is a plant-derived medicine that works like varenicline, as a partial agonist at nicotinic receptors. It has been used in Eastern Europe for decades.

Effectiveness: In the Cochrane review, cytisine helped more people quit than placebo (RR 1.30, moderate certainty). In two trials that compared it head to head with varenicline, slightly more people quit on varenicline, but the difference was not certain.

Availability: The NHS says cytisine is new to the UK and available through Stop Smoking Services and GPs. Availability elsewhere varies — ask your doctor or pharmacist.

Comparing the Options

Relative effects from the Cochrane reviews (RR above 1 means more people quit):

We don't print a single "12-month quit rate" for each option: the absolute numbers depend heavily on who is quitting, what support they get and how success is measured. People quitting on their own stay stopped for 6 to 12 months only 3–5% of the time per attempt, and every row above improves on that. Prices vary too much by country to be useful here.

The NHS adds that combining a nicotine-free medicine with a nicotine product such as patches gives the best chance of success; ask your adviser whether that suits you.

How to Get a Prescription

UK: Your GP or local NHS Stop Smoking Service, which is free.

Elsewhere: Ask your doctor or pharmacist. Many insurers and national health systems cover stop-smoking medicines, and quitlines can often help with access.

Before you start any of these: tell the prescriber about every medicine you take. Stopping smoking also changes how fast your body clears some drugs — including clozapine, olanzapine and theophylline — so doses may need adjusting once you quit.

FAQ

What is the most effective medication to quit smoking?

In the Cochrane reviews, varenicline and combination NRT (patch plus a fast-acting form) came out on top: varenicline more than doubled quit rates against placebo and beat single-form NRT, with no clear difference against combination NRT. Which suits you depends on your health and other medicines.

Is varenicline safe?

For most people, yes. The EAGLES trial of more than 8,000 smokers, including people with psychiatric conditions, found no significant increase in serious mental-health side effects compared with placebo or nicotine patches, and the FDA removed its boxed warning in 2016 — while noting the risk remains, especially for people being treated for mental illness. Nausea is the commonest side effect. The Cochrane review also found people on varenicline were slightly more likely to report a serious adverse event than people not taking it (RR 1.23, moderate certainty); it could not tell whether heart or mental-health events specifically were more common. Tell your doctor about your health history, and seek help at once if your mood or behaviour changes.

How long should I take varenicline?

The standard course is 12 weeks. The product information recommends another 12 weeks for people who have stopped smoking by then, to improve the chance of staying stopped. Talk to your prescriber before stopping early.

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