WFAA-TV

DALLAS — Tougher warnings were issued Friday for Chantix, a prescription drug used by thousands of people to quit smoking.

Pfizer, the drug's manufacturer, voluntarily updated the drug's label to include much more serious potential consequences—including an alert about suicide.

News 8 has been investigating the drug since the bizarre Labor Day death of Dallas musician Carter Albrecht. He was shot and killed by a neighbor of his girlfriend who was terrorized by Albrecht's erratic behavior.

Our reports generated thousands of complaints, and triggered, in part, an ongoing investigation by the Food and Drug Administration.

Pfizer said the labels will be updated with a warning that patients using Chantix should "be observed for serious neuropsychiatric symptoms, including changes in behavior, agitation, depressed mood, suicidal ideation and suicidal behavior."

"I think an advisory from a pharmaceutical company is an important notification step," said Dallas pulmonologist Dr. Mark Millard. "It means doctors need to be communicating with their patients that these are potentials, they're rare. They don't seem to be common given the number of prescriptions out there. But they have to recognize that if it's you it's given to, it's not rare—it's real."

These reports seem right now to be far more common than the company anticipated; that's why Pfizer is posting a more prominent warning on the box.

Chantix was approved last year as an aid to quit smoking. More than four million smokers have in the U.S. have tried the drug.

Pfizer says they don't yet know for sure whether Chantix causes depression, violent behavior, or suicide—but based on the number of complaints, they can't rule it out right now.

E-mail jstjames@wfaa.com