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