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A Case of Urticaria to Lansoprazole, Confirmed By Challenge
Saturday, March 5, 2016
South Exhibit Hall H (Convention Center)
Anita Wasan, MD, Anil Nanda, MD FAAAAI
Rationale: Lansoprazole is a proton pump inhibitor used to treat a variety of gastrointestinal conditions.  We present a case of urticaria and oral challenge to lansoprazole.

Methods: Our patient was referred for evaluation of a possible lansoprazole allergy.

Results: A 31 year old woman with a history of heartburn and diarrhea was evaluated with an upper endoscopy.  She was diagnosed with gastritis and was placed on lansoprazole.  Within a few hours of lansoprazole ingestion, she developed diffuse urticaria, which resolved with self-administered diphenhydramine.  Skin prick testing with 1:1 concentration of 15 mg/5 mL lansoprazole suspension was negative with appropriate controls.  An in office challenge was conducted to lansoprazole.  She tolerated 7.5 mg after 30 minutes.  She then was given 15 mg lansoprazole, and within a few minutes of this dose, she developed urticaria on her legs.  She was successfully treated for this allergic reaction with appropriate therapy.  In addition, she also has a history of urticaria upon ingestion of ranitidine, a histamine H2 antagonist.  In consultation with gastroenterology, an alternative therapy, sucralfate, was initiated with benefit.

Conclusions: This case demonstrates a clinical allergic (urticaria) reaction to lansoprazole, despite a negative skin prick test.  Even with negative skin testing, an oral supervised challenge is recommended.  If alternative therapies are unavailable, desensitization may be considered.