Omeprazole reduces acid gastric secretion by specific binding to the parietal cell proton pump H K+ adenosine triphosphatase.
 Uncommon (skin inflammation, urticaria, pruritus, alopecia and dry skin have been reported in 0.5 - 1.5% of patients).
Clinical manifestations
General: anaphylactic shock (one case).
Cutaneous: rashes, urticaria, angioedema (2 cases), epidermal necrolysis, contact dermatitis.
Hematological: thrombocytopenia.
Diagnostic methods
Cutaneous testing.
Prick-tests (4 mg/ ml) positive in one patient who experienced anaphylactic shock.
Drug re-challenge


  1. Ottervanger J.P, Phaff R.A, Vermeulen E.G, Stricker B.H, "Anaphylaxis to omeprazole", J. Allergy. Clin. Immunol., 1996; 97: 1413-4
  2. Bowlby H.A, Dickens G.R, "Angioedema and urticaria associated with omeprazole confirmed by drug re-challenge", Pharmacotherapy., 1994; 14 (1): 119-22
  3. Haeney M.R, "Angioedema and urticaria associated with omeprazole", B.M.J., 1992; 305: 870
  4. Meding B. "Contact allergy to omeprazole", Contact Dermatitis., 1986;
    15: 36

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.