The FDA is warning the public about Zithromax, one of the most commonly-prescribed antibiotics.
The FDA says azithromycin, which is often referred to as z-pack, has been linked to a potentially fatal irregular heartbeat.
The drug can change the heart's electrical activity and lead to a condition called a "prolonged QT interval," which means the heart's timing gets thrown off.
The FDA says doctors should be careful prescribing azithromycin for patients who are at risk for heart problems.
As the deadly epidemic spiraled out of control several weeks ago, a young specialist in infectious disease control working at the Illinois Department of Public Health volunteered to fly to the front line of the fight.