In a recent online posting by the U.S. Food and Drug Administration, the agency reported that the popular antidepressant, Celexa, can lead to potentially fatal changes in heart rhythm when used in high doses. The posting specifically outlined the drug’s interference with the heart’s electrical activity when taken in doses over 40 milligrams. Given this information, federal health regulators are now warning doctors not to prescribe the drug in doses that exceed 40 milligrams. In fact, the product label for Celexa had previously indicated that some patients should receive 60 milligrams of the drug, but the FDA has now eliminated that language based on the results of recent studies linking the higher dosage to heart problems. The drug’s new label now includes new dosage instructions, as well as in indication that the product should not be used by patients with congestive heart failure or any other conditions that negatively affect the heart’s pumping actions. Celexa is a product of Forest Laboratories and is sold in dosages of 10, 20 and 40 milligrams.