If you have persistent
asthma and take medicine every day, your doctor may ask about your exposure to
substances (allergens) that cause an allergic reaction. For more
information about the following tests, see the topic
Skin tests. The skin on the back or arms is
pricked with one or more small doses of allergens that might cause an allergy.
The amount of swelling and redness at the sites of the skin pricks is measured
to see which allergens cause a reaction. Skin tests are quick, simple, and
relatively safe. Skin tests are needed if you are interested in allergy
Enzyme-linked immunosorbent assay (ELISA).
A blood sample is taken from a vein and tested for immunoglobulin E (IgE)
antibodies, which are produced in response to particular allergens.