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Generic name: vareniclinever-EN-e-kleen ]
Drug class: Smoking cessation agents

Medically reviewed by Sanjai Sinha, MD. Last updated on Mar 9, 2023.

What is Chantix?

Chantix is a smoking cessation medicine.

Chantix is used together with behavior modification and counseling support to help you stop smoking.


When you stop smoking, you may have nicotine withdrawal symptoms with or without using medication such as Chantix. This includes feeling restless, depressed, angry, frustrated, or irritated.

Stop taking Chantix and call your doctor if you have if you feel depressed, agitated, hostile, aggressive, or have thoughts about suicide or hurting yourself.

Do not drink large amounts alcohol. Varenicline can increase the effects of alcohol or change the way you react to it.

Before taking this medicine

You should not use Chantix if you used it in the past and had:

  • a serious allergic reaction - trouble breathing, swelling in your face (lips, tongue, throat) or neck; or

  • a serious skin reaction - blisters in your mouth, peeling skin rash.

To make sure Chantix is safe for you, tell your doctor if you have:

  • depression or mental illness;

  • a seizure;

  • kidney disease (or if you are on dialysis);

  • heart or blood vessel problems; or

  • if you drink alcohol.

Tell your doctor if you are pregnant. It is not known whether varenicline will harm an unborn baby if you use the medicine during pregnancy. However, smoking while you are pregnant can harm the unborn baby or cause birth defects.

If you breast-feed while using this medicine, your baby may spit up or vomit more than normal, and may have a seizure.

Chantix is not approved for use by anyone younger than 18 years old.

How should I take Chantix?

Take Chantix exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets.

When you first start taking Chantix, you will take a low dose and then gradually increase it over the first several days of treatment. Take regularly to get the most benefit.

You may choose from 3 ways to use this medicine. Ask your doctor which method is best for you:

  • Set a date to quit smoking and start taking Chantix 1 week before that date. Make sure to quit smoking on your planned quit date. Take this medicine for a total of 12 weeks.

  • Start taking Chantix before you set a planned quit date, and choose a quit date that is between 8 and 35 days after you start treatment. Take this medicine for a total of 12 weeks.

  • Start taking Chantix and gradually reduce the number of cigarettes you smoke each day over a 12-week period, until you no longer smoke at all. Then take for another 12 weeks, for a total of 24 weeks.

Take after eating. Take the medicine with a full glass of water.

When you stop smoking, you may have nicotine withdrawal symptoms with or without using medication such as varenicline. Withdrawal symptoms include: increased appetite, weight gain, trouble sleeping, slower heart rate, feeling anxious or restless, and having the urge to smoke.

Smoking cessation may also cause new or worsening mental health problems, such as depression.

Stop taking this medicine and call your doctor if you have if you feel depressed, agitated, hostile, aggressive, or have thoughts about suicide or hurting yourself.

Store at room temperature away from moisture and heat.

Dosing information

Usual Adult Dose for Smoking Cessation:

Days 1 to 3: 0.5 mg orally once a day
Days 4 to 7: 0.5 mg orally twice a day
Days 8 to end of treatment: 1 mg orally twice a day

-The patient should set a date to stop smoking. Dosing should start 1 to 2 weeks before this date.
-Smoking cessation therapies are more likely to succeed for patients who are motivated to stop smoking and who are provided with additional advice and support.
-In smoking cessation therapy, risk for relapse to smoking is elevated in the period immediately following the end of treatment.

Use: Smoking cessation

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Get your prescription refilled before you run out of medicine completely.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What to avoid

Do not drink large amounts alcohol while taking this medicine. Varenicline can increase the effects of alcohol or change the way you react to it. Some people taking Chantix have had unusual or aggressive behavior or forgetfulness while drinking alcohol.

Do not use other medicines to quit smoking, unless your doctor tells you to. Using Chantix while wearing a nicotine patch can cause unpleasant side effects.

Avoid driving or hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.

Chantix side effects

Get emergency medical help if you have signs of an allergic reaction to Chantix (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Stop using this medicine and call your doctor at once if you have:

  • a seizure (convulsions);

  • thoughts about suicide or hurting yourself;

  • strange dreams, sleepwalking, trouble sleeping;

  • new or worsening mental health problems - mood or behavior changes, depression, agitation, hostility, aggression;

  • heart attack symptoms - chest pain or pressure, chest pain spreading to your jaw or shoulder, nausea, sweating; o

  • stroke symptoms - sudden numbness or weakness (especially on one side of the body), slurred speech, drooping of one side of the face, problems with vision or balance.

Your family or other caregivers should also be alert to changes in your mood or behavior.

Common Chantix side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Chantix?

After you stop smoking, your doctor may need to adjust the doses of certain medicines you take on a regular basis.

Tell your doctor about all your current medicines and any medicine you start or stop using. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here.

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Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Chantix only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.