The Food and Drug Administration today alerted health care providers to safety risks associated with cesium chloride, a mineral salt sometimes taken by cancer patients who seek alternative treatments. Reported adverse events included QT prolongation (a dangerous abnormality that can impair the heart’s ability to maintain a normal rhythm), low potassium, seizures, potentially lethal arrhythmias, fainting, cardiac arrest and death. FDA also said it intends to move cesium chloride to the category of substances that present significant safety risks in compounding.