Community-acquired pneumonia due to C. pneumoniae, H. influenzae, M. pneumoniae, or S. pneumoniae
Uncomplicated skin infections due to S. aureus, S. pyogenes, or S. agalactiae
Urethritis and cervicitis due to C. trachomatis or N. gonorrhoeae. In combination with ceftriaxone, azithromycin is part of the United States Centers for Disease Control-recommended regimen for the treatment of gonorrhea. Azithromycin is active as monotherapy in most cases, but the combination with ceftriaxone is recommended based on the relatively low barrier to resistance development in gonococci and due to frequent co-infection with C. trachomatis and N. gonorrhoeae. Trachoma due to C. trachomatis
Genital ulcer disease (chancroid) in men due to H. ducrey
Acute bacterial sinusitis due to H. influenzae, M. catarrhalis, or S. pneumoniae. Other agents, such as amoxicillin/clavulanate are generally preferred, however. Acute otitis media caused by H. influenzae, M. catarrhalis or S. pneumoniae. Azithromycin is not, however, a first-line agent for this condition. Amoxicillin or another beta lactam antibiotic is generally preferred. Pharyngitis or tonsillitis caused by S. pyogenes as an alternative to first-line therapy in individuals who cannot use first-line therapy

Bacterial susceptibility
Azithromycin has relatively broad but shallow antibacterial activity. It inhibits some Gram-positive bacteria, some Gram-negative bacteria, and many atypical bacteria. A strain of gonorrhea reported to be highly resistant to azithromycin was found in the population in 2015. Neisseria gonorrhoeae is normally susceptible to azithromycin, but the drug is not widely used as monotherapy due to a low barrier to resistance development.
Accidental intravenous overdose in an infant caused severe heart block, resulting in residual encephalopathy.In 2013 the FDA issued a warning that azithromycin "can cause abnormal changes in the electrical activity of the heart that may lead to a potentially fatal irregular heart rhythm." The FDA noted in the warning a 2012 study that found the drug may increase the risk of death, especially in those with heart problems, compared with those on other antibiotics such as amoxicillin or no antibiotic. The warning indicated people with preexisting conditions are at particular risk, such as those with QT interval prolongation, low blood levels of potassium or magnesium, a slower than normal heart rate, or those who use certain drugs to treat abnormal heart rhythms.It has been reported that azithromycin blocks autophagy and may predispose cystic fibrosis patients to mycobacterial infection. Pharmacology
Mechanism of action
Azithromycin prevents bacteria from growing by interfering with their protein synthesis. It binds to the 50S subunit of the bacterial ribosome, thus inhibiting translation of mRNA. Nucleic acid synthesis is not affected. Pharmacokinetics
Azithromycin is an acid-stable antibiotic, so it can be taken orally with no need of protection from gastric acids. It is readily absorbed, but absorption is greater on an empty stomach. Time to peak concentration (Tmax) in adults is 2.1 to 3.2 hours for oral dosage forms. Due to its high concentration in phagocytes, azithromycin is actively transported to the site of infection. During active phagocytosis, large concentrations are released.