BMA Concise Guide to Medicine & Drugs


Brand name Champix

Used in the following combined preparations None


Drug group Smoking cessation aid

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic No


Varenicline is an effective aid to stopping smoking in adults. It works in a similar way to nicotine in the body and helps reduce tobacco cravings. It has been shown to be more effective than nicotine replacement therapy or bupropion, and, like these, is also more likely to be successful in motivated individuals who are given additional expert advice and specialist support.

Treatment with varenicline is usually started 1–2 weeks before stopping smoking (the target stop date) and continued for a period of 12 weeks in total. The course may be repeated in people who have successfully given up but are at risk of relapsing. Adverse effects are common but not usually serious. Rarely, it may cause suicidal behaviour. You should discontinue treatment and seek immediate medical advice if you become agitated, depressed, or have suicidal thoughts while taking varenicline.


Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets.

Frequency and timing of doses Treatment started 1–2 weeks before target stop date. Initially 0.5mg once daily for 3 days, increased to 0.5mg 2 x daily for 4 days, then 1mg 2 x daily for 11 weeks (reduce to 0.5mg 2 x daily if higher dose not tolerated). Take doses at same time every day.

Adult dosage range 0.5–2mg daily.

Onset of effect 3–4 hours but may take weeks for full effect to be noticeable.

Duration of action 24 hours.

Diet advice None.

Storage Keep in original container at room temperature and out of reach of children.

Missed dose Take as soon as you remember unless your next dose is due within 12 hours, in which case omit the missed dose and take the next one as scheduled. Do not take a double dose to make up for a missed one.

Stopping the drug The drug can be stopped safely when no longer needed. However, stopping before the end of the course may increase the likelihood of a relapse.

Exceeding the dose An occasional unintentional extra dose is unlikely to cause problems, although an overdose may cause vomiting. Notify your doctor.


Headache, nausea, vomiting, tiredness, sleepiness or insomnia, and strange dreams are common adverse effects of varenicline. Discuss with our doctor if they are severe. Rarely, the drug may cause agitation, hallucinations, depression, or suicidal thoughts. If any of these occur, stop taking the drug and consult your doctor immediately.


General note Stopping smoking, with or without varenicline, may alter the effects of a wide range of drugs, sometimes necessitating a dose adjustment; important examples include insulin, theophylline, and warfarin. Consult your doctor or pharmacist if you are on other medications or before you take a new medication.


Be sure to tell your doctor if:

· You have a history of psychiatric problems.

· You have had a head injury or have a history of seizures or epilepsy.

· You have severe kidney disease.

· You are pregnant or planning a pregnancy.

· You are taking other medicines.

Pregnancy Avoid. Safety in pregnancy not established. Discuss with your doctor.

Breast-feeding The drug passes into breast milk. Safety not established. Discuss with your doctor.

Infants and children Not recommended.

Over 60 No special problems.

Driving and hazardous work Avoid such activities until you have learned how varenicline affects you. The drug may cause dizziness and sleepiness.

Alcohol Avoid. Alcohol may increase the sedative effect of varenicline.


A course of varenicline lasts 12 weeks. If necessary, the course may be repeated in those who have stopped smoking if they are likely to relapse.