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 (Zithromax) is an antibiotic medication that treats bacterial infections. It doesn’t treat viral infections. 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. Medscape - Infection-specific dosing for Zithromax (azithromycin), frequency-based adverse effects, comprehensive interactions, contraindications, pregnancy & lactation schedules, and cost. 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] 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. 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 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. It works by killing bacteria or preventing their growth. However, this medicine will not work for colds, flu, or other virus infections. This medicine is available only with your doctor's prescription. This product is available in the following dosage forms: Zithromax powder for oral suspension is a dry blend of azithromycin dihydrate 209.60 mg per 5 ml, containing the equivalent of 200 mg azithromycin base, on reconstitution with water.