Chantix (USA) or Champix (Europe and other countries), known generically as varenicline, is marketed by Pfizer as a prescription medication used to treat smoking addiction. Varenicline is a nicotinic receptor partial agonist. As a partial agonist, it both reduces cravings for and decreases the pleasurable effects of cigarettes and other tobacco products, and through these mechanisms, it is intended to assist patients in stopping smoking.

Common side effect associated with Chanitx are nauseasleep disturbanceconstipation and vomiting.

While most side effects are mild, there have been growing reports of more serious side effects. In fact, in the fourth quarter of 2007 varenicline accounted for 988 serious injuries in the U.S. reported to the FDA, more than any other individual drug in this time period. By comparison the FDA received a median of 5 reports of serious injury for 769 different drugs in the fourth quarter. Only 35 drugs accounted for 100 or more reports.

Serious side effects included:

  • depression, including suicidal thoughts and tendencies
  • aggressive behavior
  • severe allergic reactions and Stevens-Johnson Syndrome (SJS)
  • hepatitis
  • liver failure

If you have a severe allergic reaction or SJS, early symptoms may include feversore throatcough, and burning eyes.

On February 1, 2008, the FDA issued an Alert to clarify its findings, noting that “it appears increasingly likely that there is an association between Chantix and serious neuropsychiatric symptoms.”

Among the psychological side effects reported to the FDA were 28 suicides41 cases of homicidal thinking525 reports of hostility or aggression, and 397 cases of possible psychosis.

The FDA report said product label warnings need to note the medication shouldn’t be used while driving, piloting airplanes or operating machinery because it may cause unconsciousnessseizures and hallucinations.

The Federal Aviation Administration banned pilots and air traffic controllers from using Chantix in May 2008, followed immediately by a ban of the product for use by commercial truck drivers by the Federal Motor Carrier Safety Administration.

The FAA ban was prompted in part by a May 2008 report issued by the Institute for Safe Medication Practices (ISMP) detailing Chantix side effects as reported to the FDA.

The ISMP report, which used

a combination of Food and Drug Administration (FDA) adverse event reports and pharmaceutical industry Standardized Medical Queries (SMQ) to gather its data, describes a variety of instances of serious harm for which no warnings now exist, either from the FDA or from the manufacturer, Pfizer Inc.

Among the most prominent were:

  • Accidents and injuries. A total of 173 serious events described accidental injury, including 28 road traffic accidents and 77 falls, some leading to fractures of rib, facial bones, hand, ankle, spine, and lower limbs.  In these cases a variety of potential causes were identified, including loss of consciousness, mental confusion, dizziness and muscle spasms.
  • Vision disturbance. At least 148 reports contained medical terms indicating vision disturbances, including 68 cases described as blurred vision and 26 terms indicating transient or other forms of blindness. This reported effect could also describe a mechanism that could or did contribute to accidents and injuries.
  • Heart rhythm disturbances. The FDA received 224 domestic reports classified as potential cardiac rhythm disturbances. This category, however, was dominated by reports of sudden loss of consciousness, an event that could also have non-cardiac causes. However, this category also included smaller numbers of cardiac arrests and identifiable abnormal cardiac rhythms
  • Seizures and abnormal muscle spasms or movements. Serious reported events included 86 cases of convulsions (seizures), 372 reports of a wide variety of movement disorders, including tremors, muscle spasms, twitching, tics, drooling, and motor hyperactivity. The extent to which these problems resolved with a reduced dose or by halting treatment could not be determined from these data.
  • Moderate and severe skin reactions. Reported serious events included 338 cases of hives or swelling of the tongue, face, eyes, lips or other areas. In addition, 65 cases were classified as severe and included blisters, exfoliation of the skin and lips, and Stevens-Johnson Syndrome.

The results of the ISMP study are even more worrisome because FDA adverse event reporting is voluntary for consumers and health professionals, and as a result it is estimated that only 1 to 10 percent of serious adverse events are reported.


If you or a loved one has been diagnosed with severe allergic reaction, liver failure, severe depression or suicidal thoughts, Stevens Johnson Syndrome, personal injury or other serious side effects as the result of taking Chantix, you may be entitled to compensation. For a free legal consultation, contact us today!

Common misspellings: Chanticks, Chantics

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

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