Pfizer and GSK can now exhale. A study spanning 16 countries and over 8,000 patients has shown no increased risk of psychiatric side effects for smokers using smoking cessation products like Zyban and Chantix. It turns out, stopping the use of a substance that is highly addictive – both physiologically and psychologically – might just be really stressful, no matter your method for doing so. The study showed a 1.3% (Chantix users) to 2.5% (nicotine patch users) incidence of serious mental health issues, statistically the same as those taking a placebo (2.4%). The FDA is saying the study is under review. Presumably, after said review, they will decide whether the dreaded black box warning – mandated since 2009 – can go up in a puff of… well… smoke.