Azithromycin is a member of group of antibiotics called macrolides. It is used to treat infections caused by certain bacteria and other micro-organisms, which include: chest, throat or nasal infections (such as bronchitis, pneumonia, tonsillitis, sore throat (pharyngitis) and sinusitis), ear infection, skin and soft tissue infections (such as an abscess or boil) and sexually transmitted diseases caused by an organism called chlamydia  It works by disrupting the protein synthesis in microbes.