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Azithromycin  Audio icon

Other Names: Zithromax, Zmax, azithromycin dihydrate
Chemical Images:
azithromycin dihydrate azithromycin dihydrate
Molecular Weight: 785.0184
azithromycin dihydrate

What is azithromycin?


Azithromycin is an antibacterial prescription medicine approved by the U.S. Food and Drug Administration (FDA) to treat certain infections, such as:

  • Various bacterial respiratory diseases, including pneumonia and acute sinus and ear infections.
  • Pelvic inflammatory disease.
  • Genital ulcer disease.
  • Infections of the urethra, cervix, and skin.

Certain bacterial respiratory diseases (such as pneumonia) are opportunistic infections. An opportunistic infection is an infection that occurs more frequently or is more severe in people with weakened immune systems—such as those infected with HIV—than in people with healthy immune systems.

Azithromycin can also be used “off-label” to treat other opportunistic infections of HIV infection. “Off-label” use refers to use of an FDA-approved medicine in a manner different from that described on the medicine label. Good medical practice and the best interests of a patient sometimes require that a medicine be used “off-label.”


What HIV-related opportunistic infections is azithromycin used for?


The Guidelines for Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents, prepared by the U.S. Department of Health and Human Services (HHS) and the Centers for Disease Control and Prevention (CDC), includes recommendations on the HIV-related uses of azithromycin to treat bacterial respiratory diseases (such as pneumonia) and recommendations for the following “off-label” uses of azithromycin to:

  • Prevent:
    • Disseminated Mycobacterium avium complex (MAC) disease from occurring the first time (called primary prophylaxis) and from recurring (called secondary prophylaxis or maintenance therapy).
  • Treat:
    • Toxoplasma gondii encephalitis (also called toxoplasmosis).
    • Disseminated MAC disease.
    • Bacterial enteric infections, including campylobacteriosis and shigellosis.
    • Certain Bartonella infections (also called bartonellis), such as infections of the bloodstream (bacteremia) and bone (osteomyelitis).
    • Syphilis.


What should I tell my health care provider before taking azithromycin?


Before taking azithromycin, tell your health care provider:

  • If you are allergic to azithromycin or any other medicines.
  • About any medical conditions you have or have had, for example, diabetes or liver problems.
  • About anything that could affect your ability to take medicines, such as difficulty swallowing or remembering to take pills.
  • If you are pregnant or plan to become pregnant. Whether azithromycin can harm an unborn baby is unknown. Azithromycin should be used during pregnancy only if clearly needed.
  • If you are breastfeeding or plan to breastfeed. Do not breastfeed if you are infected with HIV.
  • About other prescription and nonprescription medicines, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Ask your health care provider if there are interactions between azithromycin and the other medicines you take.

Ask your health care provider about possible side effects from azithromycin. Your health care provider will tell you what to do if you have side effects.


How should I take azithromycin?


Take azithromycin according to your health care provider’s instructions. Your health care provider will tell you how much azithromycin to take and when to take it. Before you start azithromycin and each time you get a refill, read any printed information that comes with your medicine.


How should azithromycin be stored?


  • Store azithromycin injection vials below 86°F (30°C). Once the injection powder in the vial has been reconstituted with sterile water and diluted, it is stable for 24 hours at or below 86°F (30°C), or for 7 days if refrigerated at 41°F (5°C).
  • Store azithromycin extended-release dry powder for oral suspension at or below 86°F (30°C). After mixing, store the suspension at room temperature, 59°F to 86°F (15°C to 30°C). Do not refrigerate or freeze the suspension.
  • Store azithromycin dry powder for oral suspension below 86°F (30°C). Do not freeze it. After mixing, store the suspension at 41°F to 86°F (5°C to 30°C).
  • Store azithromycin tablets between 59°F and 86°F (15°C to 30°C).
  • Safely throw away azithromycin that is no longer needed or expired (out of date).
  • Keep azithromycin and all medicines out of reach of children.


Where can I find more information about azithromycin?


More information about azithromycin is available:


Last Reviewed: October 8, 2012

Last Updated: October 8, 2012