title: Lack of cross-reactivity between 5-aminosalicylic acid-based drugs: a case report and review of the literature.
abstract: BACKGROUND
  5-Aminosalicylic acid (5-ASA)-containing drugs are the mainstay of therapy in inflammatory bowel disease, but adverse reactions to these medications are relatively common. Because there may be a lack of cross-reactivity among the various 5-ASA formulations, treatment with alternative preparations is sometimes possible even after an apparent allergic reaction to a 5-ASA product.
  
  
  OBJECTIVE
  To describe a patient with a possible allergy to 2 different 5-ASA drugs who tolerated a third.
  
  
  METHODS
  A 27-year-old man with Crohn disease developed a rash while taking mesalamine (Pentasa and Asacol). Treatment with 5-ASA products was discontinued, and 6-mercaptopurine and prednisone were prescribed. He then experienced multiorgan failure secondary to herpes simplex infection, which required discontinuation of the immunosuppressive therapy. After recovery from the acute infection, he underwent successful graded challenge with balsalazide.
  
  
  RESULTS
  The patient continued treatment with balsalazide for 9 months, with good control of his inflammatory bowel disease and no adverse effects.
  
  
  CONCLUSIONS
  Adverse reactions to 1 or more 5-ASA medications do not necessarily preclude the use of others in the same class. A treatment algorithm for patients with adverse reactions to 5-ASA is outlined based on the case report and review of the literature.
authors.affiliation: Division of Allergy and Immunology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Shiang-Ju
authors.initials: SJ
authors.lastname: Kung
authors.forename: Cuckoo
authors.initials: C
authors.lastname: Choudhary
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: McGeady
authors.forename: John R
authors.initials: JR
authors.lastname: Cohn
mesh_terms: D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000276:immunology*; D003424:Crohn Disease / Q000188:drug therapy; D003429:Cross Reactions; D004342:Drug Hypersensitivity / Q000276:immunology*; D005076:Exanthema / Q000139:chemically induced* / Q000188:drug therapy; D006561:Herpes Simplex / Q000188:drug therapy / Q000209:etiology; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008297:Male; D015122:Mercaptopurine / Q000627:therapeutic use; D019804:Mesalamine / Q000009:adverse effects* / Q000276:immunology / Q000627:therapeutic use; D010659:Phenylhydrazines / Q000627:therapeutic use*; D011241:Prednisone / Q000627:therapeutic use
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D007166:Immunosuppressive Agents; D010659:Phenylhydrazines; D019804:Mesalamine; D015122:Mercaptopurine; C038637:balsalazide; D011241:Prednisone