Rat Oral LD50: >2000 mk/kg MSDS

Possible major adverse effects include cardiovascular arrhythmias and hearing loss. Macrolide resistance is also an ongoing issue.^A174172 Hepatotoxicity has been observed in rare cases.^A174175

A note on the risk of liver toxicity:

Due to the act that azithromycin is mainly eliminated by the liver, caution should be observed when azithromycin is given to patients with decreased hepatic function ^{FDA label}.

A note on potential renal toxicity:

Because limited data in patients with renal GFR <10 mL/min, caution should be exercised when prescribing azithromycin to these patients ^{FDA label}.

Use in Pregnancy:

This drug is categorized as a pregnancy category B drug. Reproduction studies have been done in rats and mice at doses up to moderately maternally toxic doses (for example, 200 mg/kg/day). These doses, based on a mg/m2 basis, are approximately 4 and 2 times, respectively, the human daily dose of 500 mg. In the animal studies, no harmful effects to the fetus due to azithromycin were observed. There are, at this time, no conclusive and well-controlled studies that have been done in pregnant women. Because animal reproduction studies do not always predict human response, azithromycin should be used during pregnancy only if clearly needed ^{FDA label}.

Nursing Mothers:

It is unknown at this time whether azithromycin is excreted in human milk. Because many other drugs are excreted in human milk, caution should be observed when azithromycin is given to a nursing woman ^{FDA label}.

Carcinogenesis, Mutagenesis, Impairment of Fertility:

Long-term studies in animals have not been performed to study carcinogenic potential. Azithromycin has demonstrated no potential to be mutagenic in standard laboratory tests. No evidence of negative effects on fertility due to azithromycin was found ^{FDA label}.