Which way would you prefer to die -- from lung cancer or a heart attack?

Those are basically the choices that users of Pfizer's (NYSE: PFE) smoking-cessation drug, Chantix, are stuck with. The Food and Drug Administration said yesterday that a warning will be added to Chantix label that notes an increase in cardiovascular events in patients taking Chantix.

In fairness, it doesn't appear that everyone is at risk for heart attacks -- just those who already have cardiovascular disease. The warning is based on a trial in patients with cardiovascular disease where heart attacks were seen more frequently than with placebo treatments. Pfizer is combining its data from previous clinical trials to determine whether the increase holds up in a larger population.

U.S. sales of Chantix peaked at just over $700 million in 2007, its first full year on the market. But warnings of potential suicide risks caused sales to come crashing down to just $330 million last year. Sales outside the United States have helped mute the drop somewhat.

I wouldn't go out and buy cigarette makers such as Altria (NYSE: MO), Reynolds American (NYSE: RAI), and British American Tobacco (AMEX: BTI) based on the newest warning, though. I imagine most doctors will still say the immediate benefits of stopping smoking will outweigh the increased risk of having a heart attack.

Plus, there's GlaxoSmithKline's (NYSE: GSK) prescription drug Zyban and the nicotine gums and patches it sells.

If worse comes to worse, doctors will suggest that patients quit the old-fashioned way: sheer willpower. The side effects -- stress and the like -- might not be so great, but death isn't usually among the risks.

Market dips giving you chest pains? Watch this before the market crashes.