What Is Allergy Testing?
Allergy testing is used by NYC allergists to determine what substances are causing a patient’s allergic reactions. Allergy testing can test for environmental, food, insect, and animal allergies. There are many types of allergy tests available. Most of these tests are performed on the skin. Allergy testing combined with a full examination by a physician can help you determine which allergens to avoid.
Skin Prick Testing
Skin prick testing is the most common method of allergy testing. During this test, the skin is slightly pricked while a small drop of allergen is exposed to the skin for about 15-20 minutes. Your NYC allergy doctor will then monitor the skin for signs of an allergic reaction, including redness and swelling. You can expect to experience some discomfort when your skin is being pricked, and also some itchiness while the allergens are allowed to react. This test is usually done to identify allergies to pollen, mold, pet dander, dust mites, and foods. Skin prick tests are generally safe for adults and children. However, this test is not recommended for people with skin conditions, such as eczema or psoriasis.
This test can deliver false results. It may show a positive result when you aren’t truly allergic to a substance. Your allergist may want to repeat the test later or suggest a different type of allergy test. In rare cases, a skin prick test can cause a severe allergic reaction. It’s important that it is administered in a clinical setting with emergency equipment nearby.
Intradermal testing is similar to skin prick testing, the major difference being that the allergen is injected under the skin to form a small bubble. The purpose of the test is to find out if a patient has specific IgE against an allergen, which is an antibody involved in an allergic reaction. If you are familiar with the test used for tuberculosis, it is the same type of injection. Intradermal testing can be more sensitive than skin prick testing. Positive results cause itching that lasts 20-30 minutes. Intradermal testing is mostly used for testing an insect sting allergy.
Since it is more sensitive, intradermal testing is usually more consistent in delivering accurate results. Allergists rely on this test when a skin prick test shows a negative result when they are almost positive you are allergic to a certain substance. To eliminate false results, you will be asked to stop taking antihistamines and other medications five to seven days before the allergy test.
Patch testing is used for allergic reactions on your skin. For example, if you develop a rash after using a new shampoo or wearing a new piece of jewelry. During the patch test, a substance is placed on a patch that is then applied to your skin. Positive reactions can be immediate or delayed. So our allergists will leave the patch on for about two days to see if you have any allergic reactions. We will also ask you to return later in the week to check for any delayed reactions.
Patch testing does not test for urticaria (hives) or food allergy. While wearing the patch, try not to avoid activities that make you sweat as this can affect results. Certain cortisones can also affect testing. This test is not recommended for those with long-term skin conditions, such as eczema.
Blood testing may be recommended by your NYC allergy specialist to measure the antibodies present in your blood. One common blood test in the field of allergy measures Immunoglobulin E (IgE). IgE is an antibody that your immune system develops in reaction to a specific allergen. Other relevant blood tests include radioallergosorbent testing (RAST), eosinophil counts, or immunoassay capture test (ImmunoCAP).
This test is best used for those will skin conditions that cannot complete a skin prick or patch test. Allergy blood tests usually test for ten of the most common allergy triggers, including dust, pet dander, trees, grasses, weeds, and molds. It can also detect food allergies.
There are no special preparations for a blood test, which makes it a more convenient option for some. There is also less risk when taking this type of test. Since the allergist is drawing blood and not injecting an allergen, you will not experience an allergic reaction. Blood tests are recommended for people who must take certain medications daily. It is also the best option for those who suffer from severe skin conditions.
Elimination Testing for Allergies
Elimination testing is when an allergist asks you to avoid a suspected allergen to see if your symptoms improve. This could mean eliminating a specific food from your diet or just changing the laundry detergent you use. During this test, you may be asked to keep a journal to document any changes. Elimination testing works best with food sensitivities.
This test usually lasts two to four weeks to deliver accurate results. If you are allergic to an eliminated substance, symptoms should disappear by the end of the trial period. For food elimination tests, your allergist may slowly introduce the suspected allergen back into your diet to see if symptoms return to confirm the allergy.
Provocation testing (also called a “challenge”) is essentially the opposite of elimination testing. In this case, the allergist will expose you to a suspected allergen in a safe, clinical setting and observe your reactions. This test is sometimes used to confirm (or disprove) a food or medication allergy (penicillin or peanuts, for example). This challenge should never be done at home. It poses severe risks and possibly life-threatening reactions. A board-certified allergist will have allergy medication on hand and ensure your safety.
Once you begin provocation testing, you should not leave the clinic until your allergist is sure you will not experience a delayed allergic reaction. This can take up to an hour. You should not attempt provocation testing if you are pregnant or have uncontrolled asthma. This test should be used as a last resort to determine an allergy.
Allergy Testing Frequently Asked Questions
Can Allergy Testing Cause Anaphylaxis?
In patients with severe allergies, allergy testing can cause anaphylaxis and other severe reactions. That’s why allergy testing should only be done in a clinical setting with a board-certified allergist.
Can Allergy Testing Determine Different Pollen Allergies?
Allergy testing can confirm grass, tree, and weed pollen allergies. You should get tested for all pollen allergies to determine which ones you are allergic to.
Can Dogs and Cats Get Allergy Tested?
Dogs can get allergy tested for skin and food allergies. It requires a vet shaving part of the animal’s fur and performing a skin prick test.
Does Allergy Testing Always Produce Accurate Results?
Allergy testing is not 100% accurate in certain situations. There are times when a positive result can show even when you aren’t truly allergic. It’s also possible to have a negative result when you really are allergic. Your allergist can combine allergy tests and track your symptoms to determine an accurate diagnosis.
How Early Should I Get Allergy Tested?
Allergists recommend getting allergy tested as early as possible. Allergy testing can be performed on infants, children, and adults.
How Is Food Allergy Testing Performed?
Most of the major food allergens can be tested with a skin prick test. In certain situations, an allergist will use a blood test to determine your food allergies.
Which Allergy Test Is Most Accurate?
Different allergy tests are more accurate for testing separate allergens. Skin prick tests work best for identifying environmental and some food allergies. Patch tests are more accurate in identifying chemical allergies. Intradermal testing is more accurate in identifying drug allergies. Blood testing is best for testing common environmental allergies. Elimination testing is more accurate in identifying food allergies. Provocation testing is also best used to confirm a food allergy. Ask your allergist which test is best for you.
Will Taking Medications Affect Allergy Testing?
Certain antihistamines and cortisone creams can affect the accuracy of your allergy test. Our allergists recommend avoiding medications for 48 hours before you get allergy tested.
If you have questions about allergy testing, the allergy specialists at NY Allergy & Sinus Centers want to help. Our physicians can determine what allergy testing you need. We will also develop a treatment plan to alleviate your allergy symptoms and help you get back to normal. We offer convenient clinics throughout NYC: Murray Hill, Midtown, Upper West Side, Chelsea, and Queens. We can even help you find relief for your asthma, nasal and sinus problems, respiratory allergies, & skin conditions. We see both pediatric and adult patients. Call 212-686-4448 to book your appointment.