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What are the side effects of varenicline?

Dr. Frank T. Leone, MD
Pulmonary Disease Specialist

Varenicline can be used to help you stop smoking, as it reduces the urge to smoke. However, it may cause some side effects. These include:

  • Nausea
  • Headache
  • Insomnia
  • Abnormal dreams

It is recommended that you take varenicline with food and/or water to reduce nausea.

As with all drugs, varenicline has some possible drawbacks you need to be aware of:

  • Before taking varenicline, tell your healthcare provider if you have any history of psychiatric illness.
  • If you have feelings of anxiety, nervousness, tension, depression, unusual behavior, or thoughts about suicide while taking varenicline or after you stop taking it, call your healthcare provider immediately.
  • If you are breastfeeding, pregnant, or hope to become pregnant, you cannot take varenicline.
  • If you are taking varenicline, you cannot use nicotine replacement therapy.
  • If very vivid and unusual dreams disturb your sleep, talk with your doctor about lowering the dose.
  • Be alert to any change in your ability to drive or operate heavy machinery.
  • As your body adjusts to varenicline, you may have digestive side effects, such as constipation and gas. If you experience nausea or vomiting, try taking the drug after eating and with a full glass of water.
  • If you have kidney problems, a lower dose of varenicline may be safer for you.

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Dr. Howard J. Shaffer, PhD
Addiction Medicine Specialist

When varenicline (Chantix) was first approved as a stop-smoking aid, doctors and smokers were eager to try it. After all, it was significantly more effective than bupropion or nicotine replacement. As is the case for all new drugs, unexpected side effects began to pop up as millions of people tried the drug. Some of the more serious problems are agitation, depression, suicidal thinking, vivid dreams, and drowsiness. The medication also has been linked to a small increase in the risk of heart attacks and related problems among people who have heart disease.

Donna Hill Howes, RN
Family Practitioner

Side effects may include aggression, anxiety, panic, depression, mania, psychosis, paranoia, hallucinations, delusions, and suicidal or homicidal thoughts or actions. Other side effects may include nausea, vomiting, constipation, insomnia, strange dreams. Varenicline can make it dangerous to drive or to operate machinery.

This answer was adapted from Sharecare's award-winning AskMD app. Start a consultation now to find out what's causing your symptoms, learn how to manage a condition, or find a doctor.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.