• celecoxib;
  • cross-reaction;
  • cross-sensitization;
  • drug allergy;
  • sulfonamides

Cross-sensitization between sulfonamides and celecoxib has been discussed in the last years (1–4), although a real cross-reactivity between them has not been demonstrated.

We report here five patients with sulfamethoxazole allergy confirmed by single-blind placebo-controlled oral challenge (SBPCOC) who tolerated oral challenge tests with celecoxib. We recruited patients that had been diagnosed of sulfonamide allergy confirmed by a positive oral provocation test in the last 4 years. Five patients were included in the study after obtaining written informed consent. The mean age of the sulfonamide allergy group of patients was 32 ± 12.21 years (mean ± SD), with a predominance of females (4 : 1), and all of them had a history of sulfomethoxazole allergy confirmed by SBPCOC as shown in Table 1. We performed SBPCOC with celecoxib reaching a cumulative dose of 200 mg obtaining a negative result in all patients.

Table 1.   Clinical characteristics of sulfonamide allergy patients
Patient numberAge (years)SexClinical symptoms in sulfamethoxazole oral challenge

Celecoxib is usually avoided in patients who have demonstrated allergic reactions to sulfonamides although there is a controversy about possible cross-reactions between sulfonamides and celecoxib. In fact few cases of clinically relevant possible cross-sensitization between these two drugs have been reported in literature.

Celecoxib is a sulfonamide-containing drug without an aromatic amine and without a substituted ring at the N1-position, so it is chemically distinct from the arylamine sulfonamide antimicrobials, and these differences are responsible of the lower potential for causing hypersensitivity reactions of celecoxib (2, 3). A meta-analysis of 14 double-blind studies showed that celecoxib, nonsulfonamide-containing nonsteroidal anti-inflammatory drugs and placebo have comparable potentials for cross-reactivity with sulfonamide-containing drugs (4).

In this study, no cross-sensitization between celecoxib and sulfomethoxazole was found. Although further investigations are necessary, scientific data at the moment show no evidence to avoid using celecoxib in patients with a known sulfonamide allergy, at least until possible cross-reaction could be confirmed by an oral challenge with the cyclo-oxygenase-2 inhibitor agent.


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