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SUMMARY Azithromycin is a broad-spectrum macrolide antibiotic with a long half-life and excellent tissue penetration. It is primarily used for the treatment of respiratory, enteric and genitourinary infections and may be used in preference to other macrolides for some sexually transmitted and enteric infections. Azithromycin has additional immunomodulatory effects and has been used in chronic respiratory inflammatory diseases for this purpose. Potential major adverse effects include cardiovascular arrhythmias and hearing loss. Macrolide resistance is also a problem, as are interactions with commonly prescribed drugs. infections. Several days of treatment is generally appropriate in respiratory tract infections and many months in mycobacterial infections. Guidelines should be consulted for detailed recommendations.9 Unlike clarithromycin, azithromycin does not interact significantly with cytochrome P450 3A4.1 In comparison with erythromycin, it is more acid stable, which simplifies administration around food. Azithromycin is a pregnancy category B1 drug and is considered safe to use in pregnancy and breastfeeding. However, it may cause diarrhoea in breastfeeding infants.9,10 Indications In Australia, azithromycin is subsidised by the Pharmaceutical Benefits Scheme (PBS) for a number of indications (see Table). It is also recommended for other infections by guidelines, but not specifically approved by the Therapeutic Goods Administration. Infections that may be treated with azithromycin include: • community-acquired pneumonia • specific respiratory infections, including pertussis and legionellosis • sexually transmitted infections such as orchitis, pelvic inflammatory disease, chancroid and granuloma inguinale9 • bacterial enteritis due to Campylobacter and Salmonella species, cholera and travellers’ diarrhoea, as well as enteric fever (caused by Salmonella enterica serovar Typhi and S. enterica serovar Paratyphi). Other recommended uses of azithromycin include treatment of severe infection or persistent lymphadenopathy due to Bartonella henselae (cat-scratch disease), and some tick-borne infections suc