New York City ? The Food and Drug Administration will require two smoking-cessation drugs, Chantix and Zyban, to carry the agency’s strongest safety warning over side effects including depression and suicidal thoughts.

The new requirement, called a “Black Box” warning, is based on reports of people experiencing unusual changes in behavior, becoming depressed, or having suicidal thoughts while taking the drugs.

The antidepressant Wellbutrin, which has the same active ingredient as GlaxoSmithKline PLC’s Zyban, already carries such a warning.