varenicline
Brand names: Chantix
Varenicline (Chantix) is a medicine that can help you stop smoking. It works on receptors in the brain to reduce cravings and withdrawal symptoms.
Drug Pricing (NADAC)
Generic Price
$0.67/unit
Generic Available
Yes (18 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Varenicline is used to help adults stop smoking.
Common side effects
Feeling sick to your stomach, Strange or vivid dreams, Constipation
Key warnings
Varenicline can cause changes in your mood or behavior.
How It Works
Varenicline works by attaching to certain receptors in your brain. These receptors are called nicotinic receptors. By attaching to them, varenicline reduces cravings and withdrawal symptoms linked to nicotine addiction.
How to Take It
Start taking varenicline one week before your quit date. You can also start taking it and quit smoking between days 8 and 35. Take the tablets after eating with a full glass of water. The usual dose is 0.5 mg once a day for days 1-3, then 0.5 mg twice a day for days 4-7, then 1 mg twice a day for 12 weeks.
Pregnancy & Breastfeeding
Tell your doctor if you are pregnant or plan to become pregnant. Varenicline may affect your unborn baby. It is not known if varenicline passes into breast milk. Talk to your doctor about the best way to feed your baby if you take varenicline.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
Storage
Store varenicline tablets at room temperature, between 68° to 77°F (20° to 25°C).
Side Effects (from patient reports)
Based on 3,717 FDA adverse event reports.
FDA Adverse Event Report Analysis
Detailed analysis of 5,766 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2007–2025.
Total Reports
5,766
Death-Related Reports
65
Hospitalization Reports
469
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | SNEEZING | 732 |
| 2 | NAUSEA | 558 |
| 3 | DRUG INEFFECTIVE | 457 |
| 4 | VOMITING | 381 |
| 5 | DEPRESSION | 349 |
| 6 | HEADACHE | 289 |
| 7 | NASAL DISCOMFORT | 260 |
| 8 | PRODUCT DELIVERY MECHANISM ISSUE | 252 |
| 9 | RHINORRHOEA | 226 |
| 10 | NIGHTMARE | 212 |
| 11 | ABNORMAL DREAMS | 210 |
| 12 | SUICIDAL IDEATION | 207 |
| 13 | COUGH | 196 |
| 14 | INSOMNIA | 188 |
| 15 | EYE PAIN | 181 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Varenicline can cause changes in your mood or behavior. These can include depression, anxiety, aggression, and suicidal thoughts. If you have these symptoms, stop taking varenicline and call your doctor right away. Varenicline may also increase your risk of seizures, accidental injuries, heart problems, sleepwalking, and severe allergic reactions.
Known Drug Interactions
Bupropion Varenicline (1 mg twice daily) did not alter the steady-state pharmacokinetics of bupropion (150 mg twice daily) in 46 smokers. The safety of the combination of bupropion and varenicline has not been established.
Mechanism: These drugs do not change each other's levels in the body, but it is not yet known if taking them together is safe.
What to do: Talk to your doctor before using these together because the safety of this combination is not yet certain.
( 7.1 ) Effect of Smoking Cessation on Other Drugs: Pharmacokinetics or pharmacodynamics of certain drugs (e.g., theophylline, warfarin, insulin) may be altered, necessitating dose adjustment. 7.2 Effect of Smoking Cessation on Other Drugs Physiological changes resulting from smoking cessation, with or without treatment with varenicline, may alter the pharmacokinetics or pharmacodynamics of certain drugs (e.g., theophylline, warfarin, insulin) for which dosage adjustment may be necessary.
Mechanism: Quitting smoking causes changes in the body that can change how well this medicine works.
What to do: Your doctor may need to change your dose of warfarin after you stop smoking.
( 7.1 ) Effect of Smoking Cessation on Other Drugs: Pharmacokinetics or pharmacodynamics of certain drugs (e.g., theophylline, warfarin, insulin) may be altered, necessitating dose adjustment. 7.2 Effect of Smoking Cessation on Other Drugs Physiological changes resulting from smoking cessation, with or without treatment with varenicline, may alter the pharmacokinetics or pharmacodynamics of certain drugs (e.g., theophylline, warfarin, insulin) for which dosage adjustment may be necessary.
Mechanism: The physical changes that happen when you stop smoking can change how your body handles this medication.
What to do: Your doctor may need to adjust your dose of theophylline once you quit smoking.
Common Questions
How long do I need to take varenicline?
Can I use nicotine patches while taking varenicline?
What if I can't quit smoking suddenly?
What should I do if I feel depressed while taking varenicline?
Can I drink alcohol while taking varenicline?
What if I have kidney problems?
Can varenicline cause sleepwalking?
What are the signs of a serious allergic reaction?
What if I still feel the urge to smoke?
Is it okay to take other medications with varenicline?
What are the common side effects of varenicline?
Does varenicline interact with other medications?
What drug class is varenicline?
Is varenicline safe during pregnancy?
Has varenicline been recalled?
Active Recalls
Sub potent drug: during the 9-month stability test conducted, the assay value for the affected lot was below specification limit.
Dr. Reddy's Laboratories, Inc.
CGMP Deviations: Presence of the N-nitroso-varenicline impurity above FDA s acceptable interim acceptable intake limit
Pfizer Inc.
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What the FDA Data Shows for varenicline
The FDA label for varenicline (sold under brand names such as Chantix) classifies it as a prescription-only medication in the Nicotinic Receptor Partial Agonist class. Varenicline is used to help adults stop smoking. Official labeling lists 5 commonly reported side effects, including Feeling sick to your stomach, Strange or vivid dreams, Constipation.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 3,717 voluntary reports. The database also lists 3 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated minor severity. NADAC pricing from CMS shows a generic unit cost of $0.67.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history (currently 2 recall records on file), and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: May 8, 2025
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages