Allergies are the result of a defect in the immune system, which causes it to overreact to normally harmless substances. Patients with allergies often benefit from being able to identify what substances trigger the allergic reaction. Allergen provocation is one method of allergy testing that can make it easier for patients to avoid allergens.
Uses
Allergen provocation, which is also known as allergen challenge, is a test which can be used to identify substances which generate an allergic reaction in patients, Medline Plus notes. With this test, the patient is exposed to a suspected allergen, which can be inhaled, placed under the tongue or injected underneath the skin. The patient must then be monitored to determine if an allergic reaction takes place. This test is slower than some other allergy tests, such as a skin prick test, because it only allows for one allergen to be tested at a time. Nevertheless, this method of testing can allow for the identification and confirmation of allergies, which can be essential to treatment.
Nasal Challenge
A nasal allergen challenge is used to identify respiratory allergies. This test, according to the BlueCross BlueShield of Tennessee Medical Policy Manual, involves applying a small amount of a solution containing a potential allergen directly into the nose. The patient is then evaluated based on the number of sneezes, inflammation of the nasal passage as well as the nasal peak expiratory flow rate, which measures the ability of the patient to breath out through his nose. If the test is negative, it may be repeated with a more concentrated allergen solution.
Food Challenge
A food challenge is an allergen provocation test which can be performed to diagnose a food allergy. For this test, the suspected allergen is mixed with some other food not suspected of causing a food allergy; this helps disguise the taste and appearance of the food that will help prevent the patient from having an adverse reaction due to the placebo effect, the Cleveland Clinic states. Ideally, this test is done under what is known as double-blind conditions, in which the patient is exposed to a suspected allergen and a non-allergenic food at different times. For this test, neither the patient nor the attending physician know which item is which. After the patient ingests the food, she must be carefully monitored for any signs of an allergic reaction.
Neutralization Testing
Neutralization testing is a subtype of food allergen testing, Food-Allergy.org explains. With this test, a known or suspected allergen is diluted into a liquid and injected under the patient's skin or placed under his tongue, after which the patient is monitored for allergic symptoms. The test is then repeated with more or less concentrated solutions to determine the maximum amount of allergen that does not generate an allergic reaction. This dose can then be used to desensitize the patient to the food allergy.
Limitations
Patients with very severe food or respiratory allergies may not be able to take place in an allergen provocation test if the allergic reaction is strong enough to be life-threatening. Because of the risk of complications, allergen provocation tests need to be administered by a trained allergist in an office or hospital environment. As a result, these tests can be very expensive. They are also less effective for patients with multiple food allergies because each allergen must be tested one at a time.
