title: Is drug allergy less prevalent than previously assumed? A 5-year analysis.
abstract: BACKGROUND
  Rashes are a frequent conundrum in clinical practice as they may be reactive, drug induced or disease specific. Identification of the culprit drug is important as re-exposure may be harmful or even life-threatening and unnecessary avoidance of 'innocent' drugs leads to limitations of treatment options.
  
  
  OBJECTIVE
  To objectify the cause of suspected cutaneous drug reactions in a large patient population.
  
  
  METHODS
  Over 5years (2006-10), 612 patients with suspected cutaneous drug reactions were evaluated. Histology was assessed. About 200 patients were invited for complete work-up with skin tests (prick/intracutaneous testing and scratch/patch as indicated) and, if necessary, lymphocyte transformation tests (LTT). In special cases, drug provocation tests were conducted.
  
  
  RESULTS
  A total number of 141 cases with suspected drug reaction underwent full work-up (age 6-86years; 75% female, 25% male). In 107 cases (76%) a drug was identified whereas 34 (24%) were reactive rashes or had other causes. Mostly, cutaneous drug reactions were maculopapular rashes, urticaria/angio-oedema; less frequently, acute generalized exanthematous pustulosis, drug reaction with eosinophilia and systemic symptoms, systemic drug-related intertriginous and flexural exanthema, toxic epidermal necrolysis and fixed drug eruptions were present. Of all the cutaneous drug reactions investigated, 39·8% were caused by antibiotics, 21·2% by anti-inflammatories, 7·6% by contrast media and 31·4% by others (oral antidiabetics, antimycotics, antipsychotics, antiepileptics and others).
  
  
  CONCLUSIONS
  Clinical assessment overestimates the role of drug allergies in cutaneous reactions. Assessment of suspected drug reactions can be greatly improved by thorough evaluation including dermatological and allergological work-up with skin testing and assays such as LTT.
authors.affiliation: Department of Dermatology and Allergies, Cantonal Hospital, St Gallen, Switzerland Department of Dermatology, University Hospital Erlangen, 91054 Erlangen, Germany. lheinzer@post.harvard.edu
authors.forename: L M
authors.initials: LM
authors.lastname: Heinzerling
authors.forename: D
authors.initials: D
authors.lastname: Tomsitz
authors.forename: M D
authors.initials: MD
authors.lastname: Anliker
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000009:adverse effects; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000009:adverse effects; D002648:Child; D003287:Contrast Media / Q000009:adverse effects; D003937:Diagnosis, Differential; D003875:Drug Eruptions / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012882:Skin Tests / Q000379:methods; D013557:Switzerland / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D000894:Anti-Inflammatory Agents, Non-Steroidal; D003287:Contrast Media