Hi,
Azithromycin is a macrolide antibiotic and falls into the same class as the more commonly used antibiotic erythromycin. It is used mainly to treat some types of chest infection (e.g. mycoplasma chest infection) as it is concentrated in the tissue where it stays for a long time, allowing for a shortened duration of drug treatment.
Its use to treat skin diseases is limited. There are a few studies showing effectiveness in treating moderately severe acne using the dose of 500mg/day, 3 days a week for a duration of 6-8 weeks.
The pro of this treatment is less frequent consumption of antibiotics.
The cons are that with all antibiotic treatment of acne, bacterial resistance may develop, and it may be best to avoid using antibiotics that are used to treat more serious medical conditions such as pneumonia just in case bacterial resistance develops over time.
Hope this helps!