More than 50 million people in the United States have allergies. Finding out what you are allergic to is an important first step to effective allergy treatment. When combined with a detailed medical history, allergy testing can identify the specific things that trigger your allergic reactions.
Numerous types of tests are available and can be performed by non-allergy providers. Some testing may lead to false diagnoses of allergies, or even false negatives. Scientifically proven and recognized allergy testing combined with the knowledge of our board certified allergists to interpret these tests, can give the most precise information as to what you are or are not allergic to.
Depending on your individual situation, our allergists may perform a specific type of allergy test for you, like skin testing, or may rely on a combination of testing types to provide the most accurate diagnosis and best treatment plan for you.
Testing done by an allergist is safe and effective for adults and children of all ages. The appropriate age to test a child may depend on the individual and their symptoms. Our allergists can help you to determine the proper age and type of testing for your child. It is often recommended to retest a child as they mature. Many times certain foods can be reintroduced that once caused an allergic reaction.
The most reliable and common test for allergies is a skin test. A skin test is a simple, in office procedure, that is best described as tiny pricks that are made on the surface of the skin on your back. The pricks are conducted with a small device called a Multitest, which is similar to a plastic toothpick. The device contains small amounts of allergens, and the skin is lightly punctured on the surface with a tiny amount of the allergens. The allergens (such as pollen, dust mite, animal dander, mold, and/or foods) will be selected by the allergist based on your medical history and symptoms. If you are allergic to an allergen, a small mosquito bite-like bump will appear. The results are available within about twenty minutes, allowing your allergist to develop a treatment plan immediately.
Skin tests are best performed in an allergist’s office to assure the test results are read properly and to minimize the risk of rare side effects. Certain medications containing antihistamines should be stopped at least five days prior to skin testing. Do not stop taking your asthma medications or other routine medications without checking with your prescribing physician
Blood tests called RAST (radioallergeosorbent test) may be performed when skin testing cannot due to medications or skin conditions. Results are not available immediately as it generally takes a week or more to obtain results of RAST testing.
Which tests are better, skin or blood?
Allergy skin testing is the most accurate and preferred method of evaluating allergies. These tests are safe, minimally invasive, and easily interpreted. Blood assays or RAST may present the clinician with diagnostic challenges. Studies have shown variability between different labs so that results can be difficult to interpret. Blood tests also may have decreased sensitivity compared to skin testing. Depending on the individual patient, more than one type of test may be utilized for an accurate diagnosis.
For those patients who do not react to suspected allergens during a skin test, an intradermal process may be performed. This is applied using a small gauge needle. The allergen is placed just under the top layer of skin. Similar to a skin test, after 20 minutes, the nurse measures the size of any reactions on the skin.
Our allergists may also perform patch testing for common contact allergens such as nickel, latex, and other chemicals.
On day one of testing, tiny amounts of up to 25 or more substances are applied as actual small “patches” to your skin. This is usually on your upper back. They are fixed on with non-allergic tape.
After two days you return to the office and the patches are removed. The skin is examined to see if there is a reaction to any of the tested substances.
After a further two days the skin is examined again in case you have a delayed reaction to any substance.
Sometimes, even after performing skin prick and blood tests, an allergist may ask you to undergo an challenge, a highly accurate diagnostic test for allergy. For example, our allergists may order the test to find out if a patient has truly outgrown a food allergy. A challenge, or challenge test, is where a very small amount of an allergen is actually inhaled or taken by mouth little by little . Following each dose, you are observed for a period of time for any signs of a reaction. If there are no symptoms, you will gradually receive increasingly larger doses. If you show any signs of a reaction, the challenge will be stopped. Challenges are done mostly with potential food or medication allergies. It is very important that they be supervised by a physician with specialized training and experience, such as an allergist, should a reaction occur.