AzithromycinAzithromycin belongs to a group of antibiotics called macrolides. It is a broad spectrum antimicrobial agent, useful against several different types of bacteria. It can be used in treating sinus infection, skin infection and several sexually transmitted infections (STIs). It is available as a Prescription only medicine (POM), and is usually taken only once a day. Azithromycin can be prescribed as a tablet, capsule or in a liquid formulation.