Once a person has been diagnosed with asthma, it is important to identify those factors that may trigger an asthma attack. Since people with asthma are more likely to also have one or more allergies, one or more allergy tests may be performed, including:

• Allergy skin tests. A small amount of an allergen is introduced to the patient’s skin. If a rash develops, the patient is most likely allergic to that substance. Allergens may be introduced to the skin by prick, scratch, patch or injection to provoke a reaction. However, these tests are not 100 percent accurate and skin testing is not practical for those with certain skin conditions (e.g., eczema, psoriasis).

  

• RAST (radioallergosorbent test). This type of blood test allows a laboratory to directly test a blood sample for antibodies that correspond to specific allergens. While less sensitive than a skin test, it can be used on individuals who have reactions too severe for a skin test.
  
  
• Bronchoprovocation test. A test that involves inducing a mild asthma attack to diagnose asthma when symptoms are not present. Most bronchoprovocation tests are performed by inhaling histamine or methacholine to induce asthma symptoms. This test can be helpful in confirming a diagnosis. A bronchoprovocation test may also involve other specific agents, such as food additives or environmental allergens, or may involve exercise (exercise challenge test). Because of the potential risks of inducing an asthma attack, this test is always performed under close supervision by medical personnel.