The US Food and Drug Administration (FDA) has informed healthcare professionals about reports of suicidal thoughts as well as some aggressive and erratic behavior in patients who have taken varenicline (Chantix, Pfizer), a smoking cessation product.

The FDA is currently reviewing these cases along with other recent reports, according to an alert from MedWatch, the FDA’s safety information and adverse reporting system. Their preliminary assessment shows that many of the cases reflect new-onset depressed mood, suicidal ideation, and changes in emotion and behavior within days to weeks of initiating treatment with varenicline, the alert said.

“The role of Chantix in these cases is not clear because smoking cessation, with or without treatment, is associated with nicotine withdrawal symptoms and has been associated with the exacerbation of underlying psychiatric illness,” the FDA MedWatch alert said. “However, not all patients described in the cases had pre-existing psychiatric illness, and not all had discontinued smoking.”

In one highly-publicized case, the FDA notes, erratic behavior led to the death of a patient using varenicline to quit smoking. “Although other factors, including alcohol consumption, appear to have played a part in this specific case, FDA asked Pfizer for additional cases that might be similar,” the agency says. “We are currently evaluating the material Pfizer submitted in response to our request.”

There are additional reports of patients experiencing drowsiness that affected their ability to drive or operate machinery, the FDA alert notes.

The FDA recommends that healthcare professionals monitor patients taking varenicline for behavior and mood changes, and that patients taking the drug should report any behavior or mood changes to their physician. Patients should also be told to use caution when driving or operating machinery until they know how quitting smoking using this agent will affect them.

The FDA is working to complete an analysis of all the materials submitted by Pfizer, and when the analysis is completed, the FDA will communicate its conclusions and recommendations to the public, the agency notes.

The complete MedWatch safety summary, including a link to the FDA Early Communication Sheet about the ongoing safety review on this issue, can be found at

Adverse events related to varenicline therapy should be reported to the FDA’s MedWatch reporting program by phone at 1-800-FDA-1088, by fax at 1-800-FDA-0178, online at, or by mail to 5600 Fishers Lane, Rockville, MD 20852-9787.

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What is Chantix? Chantix (USA) or Champix (Europe and other countries), known generically as...

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