UMEM Educational Pearls

Category: Pharmacology & Therapeutics

Title: Cross-reactivity Between Sulfonamide Antimicrobials and Non-Antimicrobials

Keywords: sulfa, allergy, cross-reactivity, antimicrobial, sulfonamide (PubMed Search)

Posted: 9/24/2012 by Bryan Hayes, PharmD (Emailed: 10/6/2012) (Updated: 10/6/2012)
Click here to contact Bryan Hayes, PharmD

Patients frequently report having a sulfa allergy. In most cases, the allergic reaction was secondary to a sulfonamide antimicrobial agent, such as sulfamethoxazole-trimethoprim.

The question is: Can I use furosemide (or other non-antimicrobial agents containing a sulfa component)?

  • There is minimal evidence of cross-reactivity between sulfonamide antimicrobials and non-antimicrobials.

  • Despite this, the U.S. FDA-approved product information for many non-antimicrobial sulfonamide drugs contains warnings concerning possible cross-reactions.

Bottom line: If a patient had a true IgE-mediated anaphylatic reaction to a sulfonamide antimicrobial, it may be best to avoid other sulfa-related medications (use ethacrynic acid if a loop diuretic is needed). Otherwise, the available literature does not support cross-reactivity between sulfonamide antimicrobials and non-antimicrobials.


Strom BL, et al. Absence of cross-reactivity between sulfonamide antibiotics and sulfonamide nonantibiotics. N Engl J Med 2003;349(17):1628-35.

Hemstreet BA, et al. Sulfonamide allergies and outcomes related to use of potentially cross-reactive drugs in hospitalized patients. Pharmacother 2006;26(4):551-7.

Lee AG, et al. Presumed "sulfa allergy" in patients with intracranial hypertension treated with acetazolamide or furosemide: cross-reactivity, myth or reality? Am J Ophthalmol 2004;138(1):114-8.

Johnson KK, et al. Sulfonamide cross-reactivity: fact or fiction? Ann Pharmacother 2005;39(2):290-301.

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