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Is Biaxin a sulfa-based drug?

Medically reviewed by Sally Chao, MD. Last updated on Oct 31, 2023.

Official answer


Biaxin (clarithromycin) is not a sulfa-based drug, and those with a known allergy to medicines that contain sulfa are not at risk of having an allergic reaction to clarithromycin.

While allergic reactions to clarithromycin are uncommon, they can occur. Potential symptoms of a clarithromycin allergy can be mild and include hives or rashes. More severe reactions may result in anaphylaxis. Before taking clarithromycin, it is important to tell your doctor if you’ve experienced an allergic reaction to clarithromycin or any of your prescription’s ingredients in the past. Also tell your doctor if you are allergic to other antibiotic drugs in the same class, including azithromycin and erythromycin.

Some antibiotics, called sulfonamides, do contain sulfa and can cause allergic reactions in prone individuals. Sulfa-based antibiotics include:

  • Septra and Bactrim (sulfamethoxazole-trimethoprim)
  • Pediazole (erythromycin-sulfisoxazole)

Non-antibiotic drugs can also be sulfonamides, including:

  • Certain drugs that treat viruses
  • COX-2 inhibitors
  • Some types of diuretics

However, having a history of allergic reactions to sulfonamide antibiotics does not mean that you will be allergic to sulfonamide non-antibiotic drugs. In fact, people with an allergy to sulfa-based antibiotics are more likely to have an allergic reaction to penicillin than to a non-antibiotic sulfa-based drug, according to the American Academy of Allergy, Asthma & Immunology.

  1. U.S. Food and Drug Administration (FDA). BIAXIN® Filmtab® (clarithromycin tablets, USP) BIAXIN® XL Filmtab® (clarithromycin extended-release tablets) BIAXIN® Granules (clarithromycin for oral suspension, USP). June 2012. Available at:,050698s029,050775s018lbl.pdf. [Accessed September 28, 2021].
  2. American College of Allergy, Asthma, & Immunology (ACAAI). Drug Allergies. February 28, 2018. Available at: [Accessed September 28, 2021].
  3. Barni S, Butti D, Mori F, et al. Azithromycin is more allergenic than clarithromycin in children with suspected hypersensitivity reaction to macrolides. J Investig Allergol Clin Immunol. 2015;25(2):128-132.
  4. U.S. National Library of Medicine MedlinePlus. Clarithromycin. June 15, 2020. Available at: [Accessed September 28, 2021].
  5. Giles A, Foushee J, Lantz E, Gumina G. Sulfonamide Allergies. Pharmacy (Basel). 2019;7(3):132. Published 2019 Sep 11.
  6. American Academy of Allergy, Asthma & Immunology (AAAAI). Acetazolamide and sulfonamide allergy. June 23, 2019. Available at: [Accessed September 28, 2021].

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