Side Effects of Zithromax, Other Antibiotics Linked to Heart Attack Risk: Study

New research suggests that side effects of Zithromax and other macrolide antibiotics may increase the risk of serious and potentially life-threatening heart problems. 

In a study published this month by the Journal of the American College of Cardiology, Chinese researchers warn that the risks of sudden cardiac death or heart rhythm problems are more than doubled when taking antibiotics that are part of a class of medications known as macrolides, the best known of which is Zithromax or Z-Pack.

Researchers looked at data from 33 studies conducted between 1966 and 2015, involving more than 20 million patients. The rates of sudden cardiac death, ventricular tachyarrhythmias (VTA), cardiovascular death and all-cause mortality were examined among those who took macrolides, other antibiotics or none at all.

The study found that rates of sudden cardiac death and VTA was about 2.5 times higher for those taking Zithromax and similar antibiotics, such as Biaxin, quinolone, and erythromycin, than those taking no antibiotics at all. However, they also found no increase in all-cause mortality.

The findings appear to confirm recent concerns about the risk of Zithromax heart rhythm problems.

The FDA issued a Zithromax drug safety communication in March 2013, warning that the antibiotic can cause serious and potentially fatal abnormal heart activity. The FDA indicated that Zithromax can disrupt the electrical activity of the heart. The agency’s conclusions came after an investigation into the risk of Zithromax heart issues that was started in May 2012, examining data from a number of studies.

In May 2012, a study published in the New England Journal of Medicine first warned about the potential heart risks. Researchers found patients were 2.5 times more likely to die due to heart related problems on a five day Zithromax treatment when they compared it to treatment with other antibiotics or no antibiotic therapy.

Macrolides have been known to cause abnormal heart rhythm problems, including QT interval prolongation. These side effects can lead to a fatal heart condition, known as torsades de pointes.

Other studies have warned of more possible problems linked to the medications. In March, a study published in PLOS One found that when pregnant women took macrolides, they were at an 80% increased risk of giving birth to a child born with cerebral palsy or epilepsy.

According to these latest findings, the side effects of Zithromax and other macrolides cause an additional 36 sudden cardiac deaths for every million treatment courses. The Pfizer antibiotic is the eighth most prescribed drug, with 56.2 million prescriptions in the U.S. in 2012.