Sulfa Allergy

written by Matthew Brady, pharmacy class of 2010, Dalhousie University

 

A sulfonamide allergy does not constitute an automatic contraindication.

There is recent medicinal chemistry research and investigation to suggest that an allergic reaction to antibiotics such as sulfamethoxazole/sulfanilamide and sulfonamide-containing drugs such as furosemide, sumatriptan, topiramate, probenicide etc does not mean an absolute cross-reactivity to furosemide.

This belief of cross-sensitivity between furosemide and other sulfonamides had stemmed from only one case report. Since the chemistry and biology of an allergy to a sulfonamide antibiotic is suspected to develop in a different mechanism than a true furosemide hypersensitivity, cross-reactivity is thought of as unlikely. Some researchers say that if someone is allergic to a sulfonamide antibiotic, and receives furosemide, and subsequently develops a hypersensitivity, then it is not because of cross-sensitivity but a sensitivity due to a different part of the molecule and perhaps a different immune response.

Thus, the allergic reaction as a result of taking these two medications may happen in a mutually exclusive fashion.

 

Resources and References

 

Johnson KK, Green DL, Rife JP, et al. 2005. Sulfonamide Cross-Reactivity: Fact or Fiction? Annals of Pharmacotherapy. 39: 290-301.