Zithromax is a prescription antibiotic that is now available for buying online. Clinical trials have shown that Azithromycin ought to be taken at least one hour pending to or two hours following meals. Azithromycin is in a class of medications called macrolide antibiotics which works by stopping the growth of bacteria. Azithromycin is in a class of medications called macrolide antibiotics which works by stopping the growth of bacteria.