I have a friend who was hospitalized for a while with suicidal depression after taking Chantix, so I've been wary of this drug for a while. Remember, never assume you're getting the full story about any drug less than ten years old. Since our government agencies rely so absurdly on companies reporting their own side effects (and we know how well that works out!), do your own research:

Hundreds of reports of suicides, psychotic reactions and other serious problems tied to the popular stop-smoking drug Chantix were left out of a crucial government safety review because Pfizer Inc., the drug’s manufacturer, submitted years of data through “improper channels.”

Some 150 suicides — more than doubling those previously known — were among 589 delayed reports of severe issues turned up in a new analysis by the non-profit Institute for Safe Medication Practices.

“We’ve had a major breakdown in safety surveillance,” said Thomas J. Moore, the ISMP senior scientist who analyzed the data. The serious problems — including reports of completed suicides, suicide attempts, aggression and hostility and depression — had been mixed among some 26,000 records of non-serious side effects such as nausea and rashes, with some dating back to 2006, the year Chantix, or varenicline, was approved.

They echo previous claims that the drug can induce extreme reactions in people trying to quit cigarettes, including vivid nightmares, crippling depression and sudden, violent outbursts.

“It’s really chilling,” said Moore, who analyzed 26 Chantix reactions in a paper published in the September 2010 issue of the Journal of Pharmacotherapy. "This seems to unleash something in people. It can be violence to anything around."