Varenicline
Pronunciation: vair-EN-i-kleen.
- Generic name
- varenicline
- Drug class
- Nicotinic acetylcholine receptor partial agonist (smoking-cessation aid)
- Form
- Film-coated tablet (0.5 mg, 1 mg)
- Route
- Oral
- Legal status
- Prescription-only
Availability and supply rules vary by country
Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand
Australia: Champix (9) · Full directory
What varenicline is and how it works
Varenicline is a prescription tablet used to help adults stop smoking. It is taken by mouth, usually starting 1-2 weeks before a chosen quit date, as part of a 12-week course (sometimes extended for another 12 weeks). (1) (5)
Varenicline partly activates the same brain receptors that nicotine acts on, which reduces craving and withdrawal symptoms, while also blocking nicotine from having its usual effect if you do smoke, which can make smoking less satisfying. It carries important warnings about mood/behaviour changes, seizures, and cardiovascular symptoms, and should be used as part of a supported quit-smoking plan.
Mechanism of action: how varenicline works
Varenicline is a selective nicotinic acetylcholine receptor (alpha4beta2) partial agonist: it stimulates receptor-mediated activity at a lower level than nicotine itself (reducing craving and withdrawal) while also competitively blocking nicotine from binding (reducing the rewarding effects of smoking if a lapse occurs). (1) (5)
What varenicline is used for
Aid to smoking cessation
Used in adults as an aid to stop smoking, alongside behavioural support/counselling for the best chance of success. (1) (5) (7)
Before taking varenicline
Do not take / not appropriate for
- Do not take varenicline if you have had a serious allergic reaction or a serious skin reaction (such as Stevens-Johnson syndrome or erythema multiforme) to it in the past. (all countries where authorised) (1)
Tell your clinician about
- Any personal history of depression, other mental health conditions, or suicidal thoughts/behaviour.
- Any history of seizures or conditions that can lower the seizure threshold.
- Any heart or blood vessel problems, including any new or worsening symptoms during treatment.
- Kidney problems, since your dose may need adjusting.
- Whether you drink alcohol -- there are reports of an interaction, including reduced alcohol tolerance and, rarely, unusual or aggressive behaviour.
- Pregnancy, plans for pregnancy, or breastfeeding.
- All other medicines you take.
- Where you live and whether the brand (Chantix/Champix) or only a generic is currently available, since brand supply has varied by country since 2021.
How to take varenicline
- Usually started 1-2 weeks before your chosen quit date, or you can start taking it and quit smoking between days 8 and 35 of treatment.
- Swallow tablets whole with water; can be taken with or without food.
- Complete the full course as directed by your prescriber -- do not stop or change your dose yourself without medical advice.
- A further 12-week course may be considered by your clinician if you successfully quit, to help maintain abstinence.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Missed dose
If you miss a dose, take it as soon as you remember unless it is close to your next dose -- in that case skip the missed dose and continue your normal schedule. Do not take a double dose. Contact your prescriber or pharmacist if you are unsure.
Overdose
Seek urgent medical attention if you think you have taken too much varenicline, particularly if you develop nausea, vomiting, or neurological symptoms such as seizures. (1)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms.
Nausea (the most common side effect, affecting up to around 30% of people).
What to notice: Nausea (the most common side effect, affecting up to around 30% of people).
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)
Abnormal or vivid dreams and sleep disturbance.
What to notice: Abnormal or vivid dreams and sleep disturbance.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (5)
Headache.
What to notice: Headache.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (5)
Constipation, flatulence, or vomiting.
What to notice: Constipation, flatulence, or vomiting.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (5)
Dry mouth.
What to notice: Dry mouth.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (5)
Serious warnings
Changes in mood, thinking, or behaviour — high caution
Symptoms: New or worsening depression, agitation, hostility, unusual behaviour, hallucinations, or any thoughts of suicide or self-harm.
Action: Contact a healthcare provider immediately, and do not take any further varenicline until you have spoken with them, if you or someone taking it notices these changes. This was the subject of a boxed warning on the US label from 2009 until it was formally removed in December 2016 after a large randomised trial (EAGLES) found no significant increase in these events compared with placebo -- it remains a genuine, actively monitored warning today, just no longer a boxed one. (1) (2) (3) (5)
Seizure — emergency
Symptoms: Convulsions, sudden loss of consciousness, or unusual jerking movements.
Action: Seek emergency medical help immediately. New or worsening seizures have been reported, including in people with no prior seizure history. (1) (5)
Signs of a heart or circulation problem — high caution
Symptoms: Chest pain or pressure, shortness of breath, or leg pain when walking.
Action: Tell your doctor promptly about any new or worsening cardiovascular symptoms; a small increase in cardiovascular events has been observed in some studies. (1) (5)
Signs of a serious allergic or skin reaction — emergency
Symptoms: Swelling of the face, mouth, throat, or limbs; difficulty breathing or swallowing; a spreading rash, blistering, or peeling skin.
Action: Seek emergency medical help immediately and do not take any further varenicline until a clinician has assessed you -- angioedema and serious skin reactions, including Stevens-Johnson syndrome, have been reported. (1)
Interactions
- Alcohol: there are post-marketing reports of an interaction with alcohol, including reduced alcohol tolerance and, rarely, unusual or aggressive behaviour -- use caution until you know how varenicline affects you. (1) (5)
- Stopping smoking itself (with or without varenicline) can change how some other medicines work, since certain drugs are processed differently in smokers versus non-smokers (for example, some doses of insulin, warfarin, or theophylline may need adjusting) -- tell your prescriber you are quitting smoking. (5)
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Smoking cessation, ideally without medicine, is recommended first in pregnancy; varenicline is generally not recommended in pregnancy unless the clinical benefit outweighs the risk, since data are limited. Discuss with your prescriber. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Breastfeeding
Varenicline passes into breast milk in animal studies; a decision on breastfeeding should be made with your prescriber, weighing the benefits of breastfeeding and of quitting smoking against any potential risk. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Children
Not established as safe/effective in children in the sources reviewed for this dossier; not indicated for use in children. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Elderly
No overall difference in effectiveness observed, but elderly patients (especially those with reduced kidney function) may need dose adjustment. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Hepatic_impairment
No dose adjustment described in the sources reviewed for hepatic impairment. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Renal_impairment
Dose adjustment recommended for moderate-to-severe kidney impairment, and dosing in severe impairment/dialysis should be individualised by a clinician. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Source_ids
US-DAILYMED-CHANTIX-CURRENT-2026,UK-EMC-CHAMPIX-2026 (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Monitoring
Before starting
- Personal/family history of depression, other mental illness, or suicidal thoughts
- Personal history of seizures
- Cardiovascular history
- Kidney function if impairment suspected
During treatment
- Watch for and promptly report any new or worsening mood, thinking, or behaviour changes.
- Report any new or worsening cardiovascular symptoms.
- Report any seizure activity immediately.
- Clinical follow-up to support the quit attempt and monitor tolerability, typically across the 12-week course.
Storage
Store at room temperature, in the original packaging, away from moisture, and out of the reach of children.
Professional information
Clinician-facing context only, sourced from the current US prescribing information and UK SmPC; verify against the current full label before prescribing, and confirm current local brand/generic availability given the 2021 nitrosamine-driven supply disruption.
United States, United Kingdom, European Union, Canada, Australia, New Zealand
Indication: Smoking cessation aid in adults
Dose summary: Days 1-3: 0.5 mg once daily. Days 4-7: 0.5 mg twice daily. Day 8 onward: 1 mg twice daily, for a 12-week course (with an optional further 12-week course for successful quitters). Start 1-2 weeks before the target quit date, or use a flexible quit-date approach (quitting between days 8-35).
Renal context: Moderate renal impairment: consider dose reduction. Severe renal impairment/end-stage renal disease: individualised, more conservative dosing under close supervision. (1) (5)
Hepatic guidance
No specific dose adjustment described in the sources reviewed for hepatic impairment.
Overdose note
Manage with supportive care; no specific antidote is described in the sources reviewed. Monitor for nausea, vomiting, and neurological symptoms including seizures. (1) (5)
Frequently asked questions
Does varenicline (Chantix/Champix) still have a 'black box' warning about suicidal thoughts?
No -- not currently. The FDA required a boxed warning about serious neuropsychiatric events (including depression and suicidal thoughts) on the US Chantix label from 2009. In December 2016, the FDA approved REMOVAL of that boxed warning, based on the large EAGLES randomised trial (run with the FDA and EMA), which found no significant increase in serious neuropsychiatric adverse events with varenicline compared with placebo, bupropion, or nicotine patch. A direct check of the current (2025-revised) US label confirms there is no boxed warning today. Neuropsychiatric symptoms are still listed as a standard warning, because some people do experience mood or behaviour changes, so you should still contact your doctor right away, and not take any further doses until you've spoken with them, if this happens to you -- it's just no longer the label's most serious 'boxed' category of warning. (1) (2) (3)
Why has brand-name Chantix/Champix been hard to find, and is it safe now?
This is a separate issue from the neuropsychiatric warning history. In 2021, Pfizer recalled brand-name Chantix/Champix worldwide after finding a nitrosamine impurity (N-nitrosovarenicline) at levels above acceptable limits -- nitrosamines are classified as probable human carcinogens at high long-term exposure, though regulators were clear the immediate health benefit of quitting smoking outweighs this theoretical risk. This caused a multi-year brand shortage. Generic varenicline filled the gap in several countries. Brand supply has since returned unevenly: it came back in the UK in mid-2025 after reformulation to lower nitrosamine levels, but brand Champix was discontinued (cancelled) in Canada, and New Zealand is replacing it with a new brand (Pharmacor Varenicline) in 2026. Always check current local availability with your pharmacist. (4) (6) (8) (10)
Can I drink alcohol while taking varenicline?
Use caution -- some people have reported reduced alcohol tolerance, or unusual or aggressive behaviour, while drinking alcohol on varenicline. Reduce your alcohol intake until you know how the combination affects you, and discuss this with your prescriber. (1)
What is the mechanism of action of varenicline?
Varenicline is a selective nicotinic acetylcholine receptor (alpha4beta2) partial agonist: it stimulates receptor-mediated activity at a lower level than nicotine itself (reducing craving and withdrawal) while also competitively blocking nicotine from binding (reducing the rewarding effects of smoking if a lapse occurs). (1) (5)
References
- CHANTIX (varenicline tartrate) tablets, film coated -- full prescribing information (Revised 6/2025)U.S. Food and Drug Administration / DailyMed (NIH), full prescribing information, Pfizer Laboratories · United States · accessed 2026-07-30 · source 1
- CHANTIX -- historical label (revised 2010) showing the original boxed warning text, for historical accuracy only -- NOT the current labelU.S. Food and Drug Administration / DailyMed (NIH), historical/superseded label · United States · accessed 2026-07-30 · source 2
- FDA Approves Removal of Boxed Warning Regarding Serious Neuropsychiatric Events From CHANTIX (varenicline) LabelingPfizer press release, corroborated by FDA advisory committee record · United States · accessed 2026-07-30 · source 3
- Pfizer Issues a Voluntary Nationwide Recall for Lots of CHANTIX (Varenicline) Tablets Due to N-Nitroso-Varenicline ContentU.S. Food and Drug Administration -- drug recall notice · United States · accessed 2026-07-30 · source 4
- CHAMPIX 0.5 mg and 1 mg film-coated tablets -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom -- Pfizer Limited · United Kingdom · accessed 2026-07-30 · source 5
- Champix (varenicline) nitrosamine recall (2021), prolonged shortage, and brand return (2025)Pharmaceutical Journal / MHRA supply-disruption alerts, corroborated by Pfizer press communication · United Kingdom · accessed 2026-07-30 · source 6
- Champix (varenicline) -- EPAR medicine overviewEuropean Medicines Agency (EMA) -- EPAR for Champix · European Union · accessed 2026-07-30 · source 7
- CHAMPIX (varenicline tartrate) -- Health Canada product listing and post-market statusHealth Canada Drug Product Database / Drug and Health Products Portal · Canada · accessed 2026-07-30 · source 8
- CHAMPIX varenicline (as tartrate) 1.0 mg tablet -- ARTG entry 124944Therapeutic Goods Administration (TGA), Australia · Australia · accessed 2026-07-30 · source 9
- Varenicline (Champix): brand change to Pharmacor Varenicline -- Pharmac medicine noticeMedsafe (New Zealand regulator) / Pharmac (Te Pataka Whaioranga) · New Zealand · accessed 2026-07-30 · source 10
Brand names by country
Single-ingredient varenicline names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- CHANTIX1 mg, .5 mg · pfizer laboratories div pfizer inc
- Tyrvaya.03 mg/.05mL · oyster point pharma, inc.
United Kingdom
Canada
- CHAMPIX
Australia
- Champix (9)TGA ARTG 124944 registered since 2007-02-15 · Pfizer Australia Pty Ltd · ARTG entry remains listed/current; affected by the 2021 nitrosamine shortage; a generic varenicline product has been available since April 2022. Exact current (mid-2026) retail brand availability could not be confirmed from a single authoritative source.
New Zealand
- Champix (10)being delisted 2026-09-01 · Pfizer New Zealand Ltd · Champix is being actively phased out in favour of a new funded brand, Pharmacor Varenicline (listed 1 January 2026, stock released to wholesalers April 2026); Champix's delisting date is 1 September 2026. Medsafe has reviewed and approved Pharmacor Varenicline as meeting international safety/quality/efficacy standards.
View brands in additional countries.
European Union
Champix (7)