Azithromycin antibiotic, which is sold under several brand names as Zithromax® and Zmax®,is commonly prescribed for various infections of the ears, lungs, sinuses, Skin, throat and reproductive organs. US FDA released a statement recently saying that this antibiotic carries the risk of causing fatal heart rhythms and this should be considered by physicians upon setting a treatment plan for patients who are at risk for cardiovascular events. High risk people include elderly, those with irregular heart rates (arrhythmias), and those with low blood levels of potassium and magnesium.
This warning came after publishing the results of a study in the New England Journal of Medicine (NEJM) which found a small increase in cardiovascular deaths among people treated with Zithromax compared to those treated with Amoxicillin or Ciprofloxacin as antibiotics or without the use of antibiotics at all.
Zithromax is a product of Pfizer although other generics exist as well.