Wednesday October 15, 2008
Cross Sulfa allergy - just a myth?

The clinical significance of cross-reactivity of medications in a person with a "sulfa" allergy continues to perplex clinicians and complicates decisions regarding patient safety. Historically, the term "sulfa" refers to a derivative of the antimicrobial agent sulfanilamide. More recently, the term has been applied to a diverse group of drugs, all of which contain the sulfonamide chemical structure (-SO2NH2).

OBJECTIVE: To provide a critical and comprehensive review of the literature, specifically case reports and observational studies used to support the concept of cross-reactivity between sulfonylarylamines and non-sulfonylarylamines.

DATA SOURCES: A list of medications was formulated from several different review articles. A MEDLINE/PubMed search was conducted (1966-March 2004) using the individual medications and the MeSH terms of drug hypersensitivity/etiology, sulfonamides/adverse effects, and/or cross-reaction.

STUDY SELECTION AND DATA EXTRACTION: A critical review of the methodology and conclusions for each article found in the search was conducted. The manufacturer's package insert (MPI) for each drug was examined for a statement concerning possible cross-reactivity in patients with a sulfonamide allergy. If indicated, the manufacturers were contacted to obtain any clinical data supporting the statement.

DATA SYNTHESIS: A total of 33 medications were identified. Seventeen (51.5%) of the MPIs contained statements of varying degrees concerning use in patients with a "sulfonamide" allergy; 21 case series, case reports, and other articles were found.

CONCLUSIONS: After a thorough critique of the literature, it appears that the dogma of sulfonylarylamine cross-reactivity with non-sulfonylarylamines is not supported by the data. While many of the case reports on the surface support the concept of cross-reactivity, on closer examination the level of evidence in many of the cases does not conclusively support either a connection or an association between the observed cause and effect.


Reference: click to get article

Sulfonamide Cross-Reactivity: Fact or Fiction? - Published Online, 11 January 2005, The Annals of Pharmacotherapy: Vol. 39, No. 2, pp. 290-301.