ABSTRACT
In order to determine the substances to which an asthmatic is allergic – such as house dust mites, grass pollen, tree pollen or animal fur – a dilute solution of the particular allergen is placed as a droplet on the forearm of the individual and then a single prick with a needle is made through the droplet. After 20 minutes, the area of redness and central raised white area, the ‘wheal and flare response’, is measured and noted.
