Why was varenicline withdrawn in 2021?

Because of a detected impurity (nitrosamine, classed as a probable carcinogen) above acceptable thresholds. The medicine has been reformulated and returned to the market in 2024 with a purified version.

Is cytisine "natural"? Is it safer?

It is plant-derived, yes. But "natural" does not mean "side-effect-free" — it can cause nausea or hot flushes. Its benefit/risk balance is overall favourable, with a strong safety record.

Can bupropion make me depressed?

Quite the opposite: it is an antidepressant, so it tends to lift mood. Like all antidepressants, it can rarely cause dark thoughts or agitation at the start of treatment — another reason to have medical follow-up.

How long do I take these medicines?

Always follow the prescribed length — stopping early raises relapse risk.

Once the course ends, does craving come back?

No, provided you complete the full course. The pills get you through the critical phase (weeks 1-12). Beyond that, your brain has already started rewiring.

If I slip while on medication, should I stop?

Not necessarily. A slip does not mean treatment failure — often you simply need to extend the course or add another tool (NRT, behavioural support). Talk to your GP before stopping anything.

Quit smoking medications: varenicline, cytisine and bupropion — effectiveness and side effects

Varenicline 25% success, cytisine 18-23%, bupropion 18%. How they work, what the side effects are, how to choose one with your GP.

June 27, 2026 Aria

The scientific basis on quitting smoking was reviewed on a voluntary basis by Pr. Bertrand Dautzenberg , a tobacco specialist, in order to rule out gross, potentially dangerous errors. It reflects positions commonly shared by health professionals and health agencies, without always corresponding exactly to his thinking or his practice. He is not the author of this text; he has only carried out a vigilance review of it.

Beyond patches and gums, there are three medications specifically licensed for stopping smoking. They are not miracle pills and not for everyone — but for many, they can double or triple the odds of staying quit. Here is what to know before going to talk to your GP.

Why pills for a cigarette?

Because nicotine dependence is not just willpower. It is a real change in the brain (nicotinic receptors, dopamine, reward circuits) that creates physical craving. These medicines target that craving — either by mimicking nicotine (varenicline, cytisine) or by acting on other circuits (bupropion).

Varenicline helps more people stop smoking than bupropion or a single form of nicotine replacement. Cytisine may be as effective as varenicline.

Cochrane Review, Livingstone-Banks et al., 2023

75 studies, 45,000 participants

Varenicline (Champix)

Common side effects

Cytisine

It's the forgotten one of stop smoking medications, yet one of the most promising.

18 to 23 out of 100

smokers succeed in quitting with cytisine. Close to varenicline.

Cochrane Review 2023, meta-analysis of 75 studies

Bupropion (Zyban)

Side effects

The table that sums it up

	Varenicline	Cytisine	Bupropion
6-month success	21-25%	18-23%	18%
Course length	12 weeks	25 days	7-9 weeks
Top side effect	Nausea	Mild nausea	Insomnia
Total cost (NHS)	Prescription charge	Prescription charge	Prescription charge
UK status	Available 2024, NICE TA	NICE recommended (TA 825, 2024)	NICE recommended
Best for	All smokers	All smokers	Depression, cannabis co-use
Avoid if	Severe psychiatric history	Severe cardiovascular disease, pregnancy	Epilepsy, eating disorder

How to choose with your GP

Score your dependence (Fagerstrom test): the stronger it is, the more useful medication becomes.
List your history

psychiatric (depression, bipolar), neurological (epilepsy), cardiac, current pregnancy.
Talk through previous attempts

what did you try? What was missing?
Pick with your GP the molecule that fits — and that you can live with (which side effects you tolerate).
Schedule follow-up at 2 and 8 weeks to adjust.

Medication + support = the real recipe

Special cases

In United Kingdom

Your questions

Why was varenicline withdrawn in 2021?

Because of a detected impurity (nitrosamine, classed as a probable carcinogen) above acceptable thresholds. The medicine has been reformulated and returned to the market in 2024 with a purified version.
Is cytisine "natural"? Is it safer?

It is plant-derived, yes. But "natural" does not mean "side-effect-free" — it can cause nausea or hot flushes. Its benefit/risk balance is overall favourable, with a strong safety record.
Can bupropion make me depressed?

Quite the opposite: it is an antidepressant, so it tends to lift mood. Like all antidepressants, it can rarely cause dark thoughts or agitation at the start of treatment — another reason to have medical follow-up.
How long do I take these medicines?

Always follow the prescribed length — stopping early raises relapse risk.
Once the course ends, does craving come back?

No, provided you complete the full course. The pills get you through the critical phase (weeks 1-12). Beyond that, your brain has already started rewiring.
If I slip while on medication, should I stop?

Not necessarily. A slip does not mean treatment failure — often you simply need to extend the course or add another tool (NRT, behavioural support). Talk to your GP before stopping anything.

sources

Livingstone-Banks J, Fanshawe TR, Thomas KH et al., Nicotine receptor partial agonists for smoking cessation, Cochrane Database of Systematic Reviews, 2023.
Anthenelli RM et al., EAGLES Study — Neuropsychiatric safety and efficacy of varenicline, bupropion and nicotine patch, The Lancet, 2016.
NICE, Cytisinicline for treating dependence on nicotine (Technology Appraisal 825), 2024.
NICE, Tobacco: preventing uptake, promoting quitting and treating dependence (NG209), 2021.
Howes S, Hartmann-Boyce J, Livingstone-Banks J et al., Antidepressants for smoking cessation, Cochrane Database, 2020-2023.