The Food and Drug Administration on Tuesday toughened a warning it made last year about the potential risks of azithromycin, a commonly used antibiotic that can cause changes in the electrical activity of the heart that may lead to a fatal irregular heart rhythm in some patients.
The risks, which have been noted in the warning labels on the drug since March 2012, were quantified in greater detail in a study published last spring in the New England Journal of Medicine that was led by a professor of preventive medicine at Vanderbilt University.
