Anaphylaxis is an acute hypersensitivity reaction, potentially fatal. Omeprazole has revolutionized the treatment of pathologies related to acid hypersecretion. There are a few case reports of anaphylactic reactions due to proton pump inhibitors (PPI). We present a case of a 30-year-old woman, with acute gastroenteritis, who received intravenous (IV) omeprazole, and immediately experienced intensive retrosterna...