how does this medication work? what will it do for me?
varenicline belongs to the class of medications called smoking cessation therapies. it is used to help people quit smoking when nicotine replacement therapy has not been effective or is not appropriate. varenicline is intended to be used by adults in combination with quit-smoking education and counselling.
varenicline works in the brain to reduce cravings and withdrawal symptoms. it also decreases the pleasure that people get from smoking. it is thought to have these effects by working at the same receptors that nicotine from cigarettes affects, although how varenicline exactly works is not clear.
this medication may be available under multiple brand names and/or in several different forms. any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. as well, some forms of this medication may not be used for all of the conditions discussed here.
your doctor may have suggested this medication for conditions other than those listed in these drug information articles. if you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. do not stop taking this medication without consulting your doctor.
do not give this medication to anyone else, even if they have the same symptoms as you do. it can be harmful for people to take this medication if their doctor has not prescribed it. do not stop taking this medication without consulting your doctor.
what form(s) does this medication come in?
0.5 mg
each capsular, biconvex, white-to-off-white, film-coated tablet debossed with "pfizer" on one side and "chx 0.5" on the other side contains 0.5 mg of varenicline (as tartrate). nonmedicinal ingredients: anhydrous dibasic calcium phosphate, colloidal silicon dioxide, croscarmellose sodium, magnesium stearate, and microcrystalline cellulose; film-coating: hypromellose, polyethylene glycol, titanium dioxide, and triacetin.
1 mg
each capsular, biconvex, light blue, film-coated tablet debossed with "pfizer" on one side and "chx 1.0" on the other side contains 1 mg of varenicline (as tartrate). nonmedicinal ingredients: anhydrous dibasic calcium phosphate, colloidal silicon dioxide, croscarmellose sodium, magnesium stearate, and microcrystalline cellulose; film-coating: hypromellose, polyethylene glycol, titanium dioxide, triacetin, and fd&c blue no. 2 indigo carmine aluminum lake.
how should i use this medication?
the usual starting dose of varenicline is 0.5 mg once daily for the first 3 days, then 0.5 mg twice daily for the next 4 days, then continue on 0.5 mg twice daily or increase to 1 mg twice daily thereafter. the maximum dose of varenicline is 1 mg twice daily. varenicline should be taken with a full glass of water, after eating.
varenicline is intended to be used in combination with quit-smoking education and counselling. there are 3 different approaches to setting a date to quit smoking (the "quit date"). talk to your doctor or pharmacist about which method would be best for you.
- in the fixed quit approach, start treatment with varenicline 1 to 2 weeks before the date you have set to quit smoking and continue for 12 weeks.
- in the flexible quit approach, start taking varenicline, then set a date to quit smoking between weeks 2 and 5 after the start of treatment. treatment should be continued for 12 weeks. for those who succeed in quitting smoking during this time, an additional 12 weeks of treatment may be recommended by their doctor to reduce the risk that they will start smoking again.
- in the gradual quit approach, start taking varenicline and decrease smoking with a goal to quit smoking by the end of 12 weeks. if you are able to, you may quit smoking at any time before the end of 12 weeks. continue taking varenicline for an additional 12 weeks, to make up a total of 24 weeks of treatment.
your doctor may suggest that you gradually decrease the dose of varenicline as you stop the medication, to reduce the risk of you starting to smoke again.
people who fail to quit smoking during the first 12-week treatment are encouraged to try again once they have identified and addressed the factors that may have caused them to have trouble quitting.
many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. if your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.
it is important that this medication be taken exactly as prescribed by your doctor. if you miss a dose, and it is within a few hours of the missed dose, take it as soon as possible and continue with your regular schedule. if it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. do not take a double dose to make up for a missed one. if you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.
store this medication at room temperature and keep it out of the reach of children.
do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. ask your pharmacist how to dispose of medications that are no longer needed or have expired.
who should not take this medication?
do not take this medication if you are allergic to varenicline or any ingredients of the medication.
do not take varenicline if you are using nicotine replacement therapy such as patches, gum, or the nicotine inhaler. combining varenicline and nicotine replacement therapy may cause more side effects than with varenicline alone and is unlikely to improve your chances of quitting.
what side effects are possible with this medication?
many medications can cause side effects. a side effect is an unwanted response to a medication when it is taken in normal doses. side effects can be mild or severe, temporary or permanent.
the side effects listed below are not experienced by everyone who takes this medication. if you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.
the following side effects have been reported by at least 1% of people taking this medication. many of these side effects can be managed, and some may go away on their own over time.
contact your doctor if you experience these side effects and they are severe or bothersome. your pharmacist may be able to advise you on managing side effects.
- constipation
- diarrhea
- difficulty concentrating
- dizziness
- flatulence (passing gas)
- headache
- increased appetite
- nausea
- sleep disturbance (difficulty sleeping or abnormal dreams)
- sleepiness
- unusual tiredness or weakness
- vomiting
- weight gain
although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.
check with your doctor as soon as possible if any of the following side effects occur:
- signs of mental changes (e.g., changes in behaviour, changes in mood, hallucinations, thinking about harming self or others)
- signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
- sleepwalking
stop taking the medication and seek immediate medical attention if any of the following occur:
- seizures
- signs of heart attack (e.g., sudden chest pain or pain radiating to back, down arm, jaw; sensation of tightness or pressure of the chest; nausea; vomiting; sweating; anxiety)
- signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort
- signs of stroke (e.g., sudden or severe headache; sudden loss of coordination; vision changes; sudden slurring of speech; or unexplained weakness, numbness, or pain in arm or leg)
- symptoms of a serious allergic reaction (e.g., puffy, swollen eyelids, lips, tongue, throat, hands or feet; hives; shortness of breath; or a severe skin rash with peeling and blistering, possibly with headache, fever, coughing, or pain)
some people may experience side effects other than those listed. check with your doctor if you notice any symptom that worries you while you are taking this medication.
are there any other precautions or warnings for this medication?
before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. these factors may affect how you should use this medication.
alcohol: consuming alcohol while taking varenicline may increase the risk of developing mood disorders or behavioural changes. you may also experience increased intoxicating effects of alcohol if you drink while taking varenicline.
allergic reaction: in rare cases, some people may develop serious allergic reactions and skin reactions to this medication. signs of an allergic reaction include a severe rash, skin changes, hives, swollen face or throat, or difficulty breathing. if these occur, seek immediate medical attention.
behaviour or mood changes: some people taking this medication experience erratic or aggressive behaviour, agitation, depressed mood, or thoughts of harming themselves or others. this can occur whether or not there is a history of psychiatric disorder. alcohol can increase the risk of experiencing these mood or behaviour changes. if you experience any mood or behaviour changes or if your friends or family observe any of these changes while you are taking this medication, stop taking this medication and contact your doctor immediately.
cardiovascular disease: varenicline may increase the risk for cardiovascular-related side effects in people who have cardiovascular disease (diseases that affect the heart or blood vessels). if you have cardiovascular disease, such as heart disease or high blood pressure, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. talk to your health care provider if you experience new or worsening cardiovascular-related symptoms, such as new or worsening chest pain, new or worse pain in legs when walking, shortness of breath, or trouble breathing.
diabetes: people with diabetes who quit smoking often experience changes in their blood sugar control. this is a result of removing the effect of nicotine on the body. if you have diabetes, discuss with your doctor how quitting smoking may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. you may be asked to monitor your blood sugar levels more frequently.
drowsiness/reduced alertness: this medication may affect the mental or physical abilities needed to drive or operate machinery. some people find that it causes drowsiness, dizziness, or decreased ability to concentrate. avoid driving, operating machinery, or performing other hazardous tasks until you have determined how varenicline affects you.
kidney function: kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. if you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
if you have kidney disease, you may be prescribed a lower dose of this medication. your doctor will monitor you while you are taking this medication.
mental health problems: if you have any type of mental health condition or any history of mental health problems, including schizophrenia, bipolar disorder, and major depressive disorder, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. if you experience any new or worsening mood or behaviour changes while taking varenicline, or if your friends or family observe any of these changes while you are taking this medication, stop taking this medication and contact your doctor immediately.
nicotine replacement therapy: varenicline should be tried as a smoking cessation therapy only after a trial of nicotine replacement therapy has been unsuccessful.
people who use nicotine replacement therapy at the same time as varenicline may experience an increase in side effects. the safety and effectiveness of taking this medication with other smoking cessation therapies such as nicotine replacement therapy have not been established.
nicotine withdrawal: symptoms of nicotine withdrawal can occur even when using varenicline.
seizures: there have been reports of seizures by people taking this medication. they have been reported by people with seizure disorders and some with no history of seizures. if you have a seizure disorder, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
if you experience seizures while taking this medication, stop the medication immediately and get medical attention.
tips on quitting smoking: varenicline is intended to be used in combination with education and counselling to help you quit smoking. if you start smoking again after your quit date, continue trying to quit. speak to your doctor or pharmacist for additional tips on quitting smoking.
pregnancy: this medication should not be used during pregnancy unless the benefits outweigh the risks. if you become pregnant while taking this medication, contact your doctor immediately.
breast-feeding: it is not known if varenicline passes into breast milk. if you are a breast-feeding mother and are taking this medication, it may affect your baby. talk to your doctor about whether you should continue breast-feeding.
children: the safety and effectiveness of this medication have not been established for children.
seniors: seniors may be more likely to experience side effects when taking this medication.
what other drugs could interact with this medication?
there may be an interaction between varenicline and any of the following:
- alcohol
- nicotine replacement therapy
stopping smoking can cause a change in the way your body uses some medications. if you are taking any of the following medications, the doses of these medications may need to be changed once you are smoke-free.
- insulin
- theophylline
- warfarin
if you are taking any of these medications, speak with your doctor or pharmacist. depending on your specific circumstances, your doctor may want you to:
- stop taking one of the medications,
- change one of the medications to another,
- change how you are taking one or both of the medications, or
- leave everything as is.
an interaction between two medications does not always mean that you must stop taking one of them. speak to your doctor about how any drug interactions are being managed or should be managed.
medications other than those listed above may interact with this medication. tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. also tell them about any supplements you take. since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.
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