Hypersensitivity to proton pump inhibitors: lansoprazole-induced Kounis syndrome

Proton pump inhibitors are commonly used in clinical practice for the treatment of peptic ulcer and gastroesophageal reflux and are well tolerated by the patients. Their use is rarely associated with hypersensitivity and anaphylactic reactions. According to the reports in the Uppsala Monitoring Center database the frequency of hypersensitivity reactions out of all reported adverse reactions for proton pump inhibitors and H2-histamine receptor antagonists was between 0.2% and 0.7%. A few cases of hypersensitivity to lansoprazole have been reported. We report a patient who developed Kounis syndrome after taking 30 mg of lansoprazole. This is the first report of Kounis syndrome associated with lansoprazole administration in the world literature.