Skin Prick Testing
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Skin Prick Allergy Testing
There are three types of skin testing methods to determine if you are allergic to a certain substance. The most common of the three is what is called a “Skin Prick Test”. This test can also be referred to as a skin scratch or puncture test.
What is a Skin Prick Test?
A Skin Prick or Skin Scratch test is a method used to check for immediate allergic reactions to as many as 40 different allergens at once. A skin prick test is administered to identify allergies to pollen, mold, pet dander, dust mites, and food allergies. The tests are done in 1 of 2 places which are the forearm and upper back. The forearm is used mostly for adults while upper backtests are performed on children.
These tests are not painful, as it uses tiny needles that barely penetrate the surface of the skin, in most to all cases you won’t even bleed. Due to the possibility of a reaction, there could be mild to moderate discomfort.
How is a Skin Prick Test Done?
The first step to performing a Skin Prick test is to make sure the area is clean, by using alcohol swabs. Once the test site has cleaned a nurse will draw small marks on your skin’s surface then will apply a drop of allergen extract next to each mark. Using a “Lancet” the nurse will then prick the extracts into the skin’s surface, using a new lancet each time to make sure the allergens are not mixed.
For better and faster results there will be 2 additional substances used along with the allergens. These 2 substances are a Histamine and Glycerin (saline).
A Histamine is used to help cause a skin response to the allergens, If a person doesn’t react to a histamine then there is a possibility that your allergy skin test may not reveal an allergy even if you have one.
Glycerin is a type of saline is to test to see if you have sensitive skin. Most people will not react to glycerin or saline.
How Long Does a Skin Prick Test Take?
A skin prick test takes 10 minutes to administer and then another 15 minutes of wait time for a reaction to occur. A nurse will observe your skin and watch for signs of a reaction.
How Will You Know If I’m Allergic to an Allergen?
If you are having an allergic reaction to one of the allergen extracts, you will develop raised, itchy, red bumps that may look like a mosquito bite. To see how allergic, you are to the substance, the nurse will then measure the size of the bump, so we can determine the severity of the allergy.
Is Skin Prick Allergy Testing Accurate?
Skin prick allergy testing is one of the most effective diagnostic approaches available to an allergist. The test identifies whether a person responds positively or negatively to various environmental and food allergens, enabling a rapid diagnosis. However, as with other skin allergy test options, these results need careful review and interpretation from an experienced allergist.
According to Food Allergy Research and Education, skin prick allergy testing rarely produces false negatives. A false negative means the test shows a negative result, yet the person is actually allergic to the substance. And while testing could produce a false positive, an allergist uses additional information (and potentially other testing options) to confirm the results.
Allergy Test Safety
Allergy skin tests are equally safe for both adults and children. However, we strongly recommend informing us of any medications that you or your child may be taking prior to scheduling the skin test, as some medications may interfere with the results.
What Medications Can Interfere with Allergy Testing Results?
Before your doctor can schedule a test, make sure that they know about all your prescription and non-prescription medication that you take. Some medications can alter the allergic reactions caused during the test, or not show a reaction at all. To make sure that your getting 100% results out of the performed testing the doctor and allergy specialist will need to know this detailed information.
For some medications, it takes time for all the medication to clear out of your system. Depending on the medication that you are taking, your doctor may request that you stop taking certain drugs for up to 10 days. Some of the medications that can interfere with a skin test include:
- Prescription Antihistamines: Levocetirizine (Xyzal) and Desloratadine (Clarinex).
- Over-The-Counter Antihistamines: Loratadine (Claritin, Alavert), Diphenhydramine (Benadryl, etc.), Chlorpheniramine (Chlor-Trimeton), Cetirizine (Zyrtec, etc.) and Fexofenadine (Allegra).
- Tricyclic Antidepressants: Nortriptyline (Pamelor) and Desipramine (Norpramin).
- Some Heartburn Medications: Cimetidine (Tagamet) and Ranitidine (Zantac).
- Asthma medication: Omalizumab (Xolair)
Contact a Local Allergist
To learn more about our allergy testing and/or to schedule an appointment, contact Chacko Allergy, Asthma and Sinus Center at one of our six convenient locations – Alpharetta, Atlanta, Canton, Cumming, Duluth or Johns Creek. You request an appointment online or call us at 678-668-4688.