Washington: An antibiotic used to treat common infections may carry serious heart risks, scientists have warned.
The drug, called azithromycin but sold under the brand names Zithromax and Zmax as Z-Pak capsules, is prescribed for infections of the ears, lungs, sinuses, skin, throat, and reproductive organs, according to the US Food and Drug Administration (FDA).
But the antibiotic can interfere with the heart`s electrical activity, disturbing its rhythm with potentially fatal consequences, ABC News reported.
"Health care professionals should consider the risk of fatal heart rhythms with azithromycin when considering treatment options for patients who are already at risk for cardiovascular events," the FDA said in a statement.
Elderly people and those with irregular heart rates, arrhythmias, and low blood levels of potassium or magnesium are at a particularly high risk for the deadly heart condition, the FDA said.
The warning comes 10 months after a study found a small increase in cardiovascular deaths among people treated with Zithromax compared to those given the antibiotics amoxicillin or ciprofloxacin or no treatment at all.
At the time, the FDA urged patients taking Zithromax to "not stop taking their medicine without talking to their healthcare professional" - a recommendation that stands today, despite the new warning.
Zithromax, made by Pfizer, comes in tablet and liquid form and is usually taken for up to five days.
The drug`s labels have been updated to strengthen the warnings and precautions section.
While alternatives to Zithromax are available, the FDA warned that they, too, can carry "other significant side effects that should be considered when choosing an antibacterial drug."
People taking Zithromax should seek immediate medical care in the event of an irregular heartbeat, shortness of breath, dizziness or fainting, the FDA added.
The study is published in the New England Journal of Medicine.