extrinsic asthma (features of)

Last reviewed 01/2018

  • history of allergy:
    • the most common allergen involved in the development of extrinsic asthma worldwide are the faecal particles of the house-dust mite
    • other common allergens include:
      • occupational allergens:
        • IgE related causes include allergens from flour and grain, e.g. in farmers
        • complex salts of platinum in metal refining
        • acid anhydrides used in industrial coatings
      • drugs - NSAID's and food additives such as tartrazine; patients with extrinsic asthma are not aspirin sensitive
  • aspergillus
  • family history of atopy
  • early onset
  • attacks often seasonal
  • occasional polyps
  • investigation - eosinophilia; elevated IgE; skin prick test positive
  • good response to beta agonists and disodium chromoglycate