A recent study shows children whose mothers took macrolide antibiotics such as Zithromax while pregnant have an increased risk of developing cerebral palsy or epilepsy.

The study was published in the online journal PLOS One in March 2015. Researchers from the United Kingdom studied over 64,000 women who took antibiotics during pregnancy. While the researchers found no overall association between antibiotic treatment during pregnancy and later development of cerebral palsy or epilepsy, they did find that those who took macrolide antibiotics had an almost 80 percent greater risk of having children with cerebral palsy or epilepsy as compared to those who took a penicillin-based antibiotic.

Zithromax Side Effects

Zithromax
is a macrolide antibiotic made by Pfizer Inc. It is also sold as Z-Pak, Zmax and under its generic name azithromycin. Since the FDA first approved Zithromax in 1992, its list of approved uses has expanded to include treatment of a variety of bacterial infections.

Indicated uses now include bronchitis, pneumonia, sinusitis, pharyngitis and tonsillitis, staph and strep infections, urethritis and cervicitis due to chlamydia and gonorrhea, and men’s genital ulcer disease caused by chancroid. In children of certain ages, it’s approved for treatment of acute otitis media, pneumonia, and pharyngitis or tonsillitis.

Even in the face of competition from generic versions of the drug, Zithromax sales have remained brisk. Sales exceeded $450 million in 2011 and $430 million in 2012. The typical course of Zithromax is short at only five days, which could contribute to its popularity.

But despite Zithromax’s popularity, studies have found several other harmful Zithromax side effects beyond the birth defects found in the March 2015 study.

In March 2013, the FDA issued a Drug Safety Communication warning consumers and the medical community that azithromycin can cause electrical changes in the heart that can lead to potentially fatal irregularity in the heart’s rhythm.

The communication said that those patients most at risk for this complication are those with an existing QT interval prolongation (a type of heart rhythm abnormality), low levels of potassium or magnesium in the blood, an abnormally slow heart rate, or an existing arrhythmia. With that communication, the FDA also strengthened the warning label on azithromycin to address the increased risk of heart side effects.

Zithromax can also cause dermatologic side effects as severe as Stevens Johnson Syndrome or its related condition toxic epidermal necrolysis. These conditions cause the outer layer of skin to blister and peel as if it had been severely burned. Severe cases can require weeks of hospitalization and several months of total recovery time. The worst cases are life-threatening.

Hepatoxicity has also occurred in Zithromax users, sometimes leading to liver damage and liver disease. Courses of Zithromax have led to abnormal liver function, hepatitis, and cholestatic jaundice. Rare cases have led to hepatic necrosis and hepatic failure, some of which resulted in death.

Though rare, kidney side effects have also been associated with Zithromax use. Some Zithromax treatment has led to elevated serum creatinine and blood urea nitrogen, both signs of impaired kidney function. A few cases have led to nephritis and kidney failure.