Medscape - Infection-specific dosing for Zithromax (azithromycin), frequency-based adverse effects, comprehensive interactions, contraindications, pregnancy & lactation schedules, and cost. Overview: Azithromycin is an antibiotic that is used to treat certain bacterial infections. It works by stopping certain types of bacteria from making proteins they need to grow and multiply. Azithromycin is a semi-synthetic antibiotic of the azalide subclass, derived from the classical macrolide erythromycin by the insertion of a methylated nitrogen atom into the 14-membered macrolactone ring, expanding it to a 15-membered ring. Azithromycin is used alone or in combination with other medicines (eg, ethambutol and rifabutin) to prevent and treat Mycobacterium avium complex (MAC) disease from causing disease throughout the body in patients with advanced human immunodeficiency virus (HIV) infection. Zithromax or Z-PAK (azithromycin) is a semi-synthetic macrolide antibiotic used for treating bacterial infection. Learn about dosages, side effects, drug interaction, warnings, and more. Azithromycin, sold under the brand names Zithromax (in oral form) and Azasite (as an eye drop), is an antibiotic medication used to treat several bacterial infections. [9] Azithromycin is used to treat many different types of infections caused by bacteria, such as respiratory infections, skin infections, ear infections, eye infections, and sexually transmitted diseases. Azithromycin may also be used for purposes not listed in this medication guide. Learn about azithromycin (Zithromax) usage and dosing. Read the latest news and reviews about the drug as well as potential side effects and popular alternatives. Zithromax is an antibiotic that fights bacteria. Zithromax is used to treat many different types of infections caused by bacteria, such as respiratory infections, skin infections, ear infections, and sexually transmitted diseases. Azithromycin (Zithromax) is an antibiotic medication that treats bacterial infections. It doesn’t treat viral infections.