“We have immediate safety concerns about the use of varenicline (Chantix) among persons operating aircraft, trains, buses and other vehicles, or in other settings where a lapse in alertness or motor control could lead to massive, serious injury,” the researchers said in the report.

FAA spokesman Les Dorr said the Chantix ban is effective immediately and that the agency was notifying unions representing pilots and controllers. He said the FAA is unaware of any aviation accident caused or contributed to by Chantix. Pfizer, in a statement, reaffirmed its stand on the drug’s safety and said the label already contains safety warnings about driving or operating machinery.