Omeprazole Induced Rapid Drug Reaction with Eosinophilia, Systemic Symptoms, and Cross-Reactivity in Delayed-Type Hypersensitivity Associated with Proton-Pump Inhibitors: A Case Report and Literature Review.

Background: Omeprazole, a proton pump inhibitor (PPI), is a widely used and generally safe agent for treating acid-related gastrointestinal conditions. However, drug reaction with eosinophilia and systemic symptoms (DRESSs) syndrome has been reported.

Objectives: To report a case of omeprazole-induced rapid DRESS syndrome and to review the literature.

Methods: Descriptive analysis of one new case and a case series from literature review.

Results: We report a case of 82-year-old woman presenting with rapid-onset of DRESS syndrome. The condition was initially suspected to be caused by antibiotic, but the definite diagnosis was eventually omeprazole-induced DRESS syndrome as suggested by the enzyme-linked immune absorbent spot (ELISpot) assay along with the clinical picture. Previous literatures regarding cases of PPI-induced DRESS syndrome were pooled for descriptive analysis. Among 21 PPI cases pooled, esomeprazole was the most commonly implicated PPI (52.4%), followed by pantoprazole (19.1%), and omeprazole along with lansoprazole (both 14.3%). The issue of cross-reactivities amongst PPIs remains uncertain. Nonetheless, in situations in which a PPIs are deemed necessary, a prudent approach could be considering a switch to an alternative agent with distinct chemical structure.

Conclusion: PPI is commonly used safely as an agent for acid-related gastrointestinal conditions. However, PPI-induced rapid DRESS syndrome can occur, particularly with prior exposure history. ELISpot is an in vitro test, useful in identifying the culprit agent in patients with delayed-type hypersensitivity reaction.