Several studies have demonstrated different cross-reactivity patterns between proton pump inhibitors (PPIs). The aim of this study was to investigate cross-reactivity between commercially available PPIs and establish a procedure for performing cutaneous tests for verifying PPI allergy.
We performed skin prick and intradermal tests with all commercially available PPIs in 5 patients with clinical allergy to omeprazole and observed positive results in all patients.
We report 5 cases of immunoglobulin (Ig) E–mediated allergy to omeprazole and document cross-reactivity by skin testing between all the PPIs studied. We also found that the probability of confi rming an IgE-mediated mechanism with skin tests decreases with time. Finally, we propose a hypothesis that could explain the different PPI cross-reactivity patterns reported.

Key words: Esomeprazole. Lansoprazole. Omeprazole. Pantoprazole. Proton pump inhibitors. Rabeprazole.