Chantix (also known as Varenicline) is a prescription medication designed to help smokers kick the habit. The side effects listed on the label include nausea, changes in dreaming, constipation, gas and vomiting. In addition to the side effects listed on the box, there's also an insert that lists psychotic and suicidal behavior are possible.

Since it's approval, many Chantix users have reported side effects of hallucinations, confusion and violence, particularly if alcohol was involved. These extreme side effects have been reported as early as a few days after first taking Chantix and have been blamed for the death of a Dallas musician. Carter Albrecht was taking Chantix to help quit smoking. About a week after starting the drug, he assaulted his girlfriend at her home, and then started banging violently on a neighbor’s door. He girlfriend reported he was confused and did not even know who she was. His neighbor accidentally shot and killed him while Albrecht was reportedly trying to enter the house. Friends and family state Albrecht had never been violent or shown any similar behaviors before taking Chantix.

Many other Chantix users reported violent or suicidal thoughts and behavior, especially when they had consumed alcohol. The Chantix label mentions alcohol use, but does not indicate extremem violence and / or hallucinations could be the result.

The Food and Drug Administration's list of adverse side effects and found thousands of similar and very serious reactions to Chantix. Pfizer's patient information insert for Chantix lists only five common side effects. But in a separate insert meant for doctors, some rare and frightening adverse reactions appear listed in 1-millimeter size print. The list includes things like suicidal thoughts, aggression, and neurological and psychiatric disorders.

Chantix went on the market in August 2006. Pfizer tested it on fewer than five thousand people, which is considered normal.