Azithromycin dosage for Chlamydia. Azithromycin is a broad-spectrum antibiotic that is a second-generation antibiotic in the macrolide class. Azithromycin is mainly used for the treatment of Chlamydia pneumoniae or other infectious bacteria. And the dosage of azithromycin in the treatment of Chlamydia infection is 0.5g/dose for adults, one dose in a single dose, the course of treatment is 3 days, or the first dose is given 0.5g. After that 0.25g per day for 5 days. For children over 6 months of age who weigh less than 45 kg. The daily dose is basically 10mg/kg, and the dosage and course of treatment are the same as those for adults.