It has been warned by the US Food and Drug Administration that Pfizer's anti-smoking drug, Chantix, leads to suicidal behavior and also causes other psychiatric side-effects. The agency issued the warning after it reviewed company findings, according to which the drug does not lead to such problems. The drug is reported to cause suicidal tendencies and aggressive or strange behavior among some patients.

On Monday, the FDA gave many updates about Chantix's labeling in which it also warned that the drug could also interact with alcohol. It has been reported by some patients that they experience bizarre or aggressive behavior, when they drink during the course of the drug.

According to FDA, "Until patients know how Chantix affects their ability to tolerate alcohol, they should decrease the amount of alcohol they drink. Patients who have a seizure while taking Chantix should stop the medicine and seek medical attention immediately”.

Chantix is also known as varenicline, which is its chemical name. The drug was approved in 2006. After some time, the agency updated label for inclusion of a warning, shown by a black box, of neuropsychiatric side effects, together with hostility, suicidal thoughts and agitation.

The company wants the agency to remove the black box and said that the studies, which were conducted by the company, show no link between Chantix and severe psychiatric side effects. An additional safety study of the drug is also being conducted by the company. In 2014, the drug managed to generate $647 million in revenue. Results of the study will probably be announced in late 2015. As per FDA, it will be keeping the black box in place till the announcement of trial results.