If you suffer from severe allergies during certain times of the year or in certain parts of the country, you may not know what’s triggering your allergies. Knowing which triggers to avoid is one of the most important things you can do to drastically reduce your symptoms. At Asthma Allergy Centre in Tigard, OR, we believe everyone should be able to breathe easily. Today, we’re discussing an allergy skin test and if it can work for you.
How Should I Prepare for an Allergy Skin Test?
To determine if you need an allergy skin test, your allergy specialist will thoroughly review your medical history, signs and symptoms and how you currently treat your allergy attacks. This will help your doctor determine if you have a family history of allergies and if your symptoms are most likely caused by an allergic reaction. You may also need to receive a physical examination to diagnose allergies as the trigger for your signs and symptoms.
Medications Can Interfere With Your Results
During your initial consultation, bring a list of all prescription and over-the-counter medications you are currently taken. Certain medications can minimize allergic reactions. This will prevent the allergy skin test from delivering accurate results. Other types of medications may lend themselves to a more significant allergic reaction during your skin test.
Since everyone’s body metabolizes medications at different rates, we recommend you stop taking most medications for 10 days before your skin test. Medications that can affect the results of a skin test include:
- Prescription antihistamines – desloratadine (Clarinex) and levocetirizine (Xyzal)
- Tricyclic antidepressants – nortiptyline (Pamelor) and desipramine (Norpramin)
- Heartburn medications – cimetidine (Tagamet) and ranitidine
- Asthma medications – omalizumab (Xolair)
What to Expect
Allergy skin tests typically take only 20 to 40 minutes. Some tests are used to detect immediate allergic reactions. The results of these tests are seen within minutes of exposure to allergens. Other tests result in the development of delayed allergic reactions. The results from these tests cannot be seen for several days.
Skin Prick Test
A skin prick test, also known as a scratch test or puncture test, is used to check for immediate allergic reactions. This type of test can detect allergic reactions to up to 40 different substances at the same time. This test is most often used to identify allergies to foods, pet dander, mold, pollen and dust mites. In children, this test is usually performed on the upper back. In adults, you can expect the test to be performed on the forearm.
The skin prick test is not painful. The tiny lancets, or needles, used to administer the potential trigger barely penetrate the surface of your skin. You will not bleed or feel any discomfort after your treatment.
How It’s Performed
Before your test, the site is cleaned with rubbing alcohol. Once the test site is sterilized, tiny marks will be drawn on your skin. A single drop of allergen extract is applied to each mark. Then, the lancet is used to prick the extracts into the surface of the skin. To ensure the most accurate results, a new lancet will be used to administer each allergen.
Two additional substances are scratched into the surface of your skin to ensure your skin is reacting normally. First, histamine will be used to cause a skin response. If you do not react to histamine, your skin prick test may not reveal an allergy even if you are allergic to a tested substance.
The second substance you will be given is saline or glycerin. These substances rarely cause a reaction. If you react to one of these substances, your skin may be sensitive. The results of your skin prick test will need to be interpreted very cautiously to ensure you are not given a false allergy diagnosis.
After the Test
Roughly 15 minutes after the skin pricks have been made, your skin will be observed for signs of allergic reactions. If you are allergic to any of the substances tested, you will develop a raised, red wheal that looks similar to a mosquito bite. The size of the wheal is measured and noted. Then your skin is cleansed with alcohol to remove the marks made before the test.
Skin Injection Test
The skin injection allergy test can work for you if you’re trying to test an allergy to penicillin or insect venom. This type of test involves the injection of a tiny amount of allergen extract. It is applied intradermally in the skin on your arm. The site of the injection is evaluated after roughly 15 minutes for signs of an allergic reaction.
Patch testing can work for you if you want to see if a certain substance is causing contact dermatitis, also known as an allergic skin irritation. These tests can be used to detect delayed allergic reactions which will not develop for several days.
As the name suggests, a patch test does not involve the use of any needles. Rather, the allergens are applied to your skin via patches. You can use the patch test to expose your skin to 20 to 30 substance extracts which can trigger contact dermatitis. Some of the most common substances tested using patches are resins, metals, preservatives, hair dyes, fragrances, medications and latex.
How the Test Works
During this test, you will wear the patches on your back or arm for 48 hours. Until the test is over, avoid bathing and any activity that causes heavy sweating. This includes relaxing in a sauna, playing intense team sports, performing high-intensity interval training and running at a rapid rate. After 48 hours of wearing the patches, you will return to the office so the patches can be removed. If your skin is irritated at the test site, you may have an allergy to the substance.
Should I Get a Skin Test?
There are several reasons to consider a skin test for allergies. Knowing exactly what you are allergic to allows you to implement the most effective treatment plan possible. Effective treatments may include immunotherapy (allergy shots), allergen avoidance and medications. Skin tests are often used to diagnose certain allergic conditions, including:
- Allergic rhinitis (hay fever)
- Allergic asthma
- Eczema (dermatitis)
- Food allergies
- Penicillin allergy
- Bee venom allergy
- Latex allergy
In almost all cases, skin tests can work for you. They are safe for children and adults of all ages, including infants. However, there are a few circumstances under which an allergy test may not work for you. These include having a history of severe allergic reactions, taking certain medications and having certain skin conditions.
If you suffer from dermatographism, a skin test may not work for you. This condition can cause false positives during testing. If you suffer from severe psoriasis or eczema on large areas of your back and arms, where testing usually takes place, you may not have enough uninvolved, clear skin for an effective test to be performed.
Certain medications, including antihistamines, certain heartburn medications and most types of antidepressants, can affect the results of the test. During your initial consultation, we will help you determine if it is best for you to continue taking these medications and take a different type of allergy test. If we determine that a skin test is right for you, we will advise you on how to discontinue them safely until after your skin test.
History of Severe Allergic Reactions
If you have ever suffered from anaphylactic shock, a skin test is not right for you. Depending on your sensitivity to a given allergen, even a tiny amount of an allergen can trigger anaphylaxis.
Alternatives to Skin Tests
What if a skin test won’t work for you? How do you identify your triggers? In vitro immunoglobulin E antibody tests, more commonly called blood tests, can be an excellent alternative for individuals who shouldn’t undergo a skin test. Allergy blood tests are often used to screen for dust, pet dander, local trees, local grasses, local weeds and molds. They are even more effective at diagnosing food allergies than skin testing. Similar to a skin test, a blood test can screen for at least 10 triggers at the same time.
Will An Allergy Blood Test Work for Me?
An allergy blood test can work for you if you are taking medications that can interfere with the results of a skin test, but you cannot stop taking these medications for a few days. It can also work for you if you have an unstable heart condition, poorly controlled asthma, a severe skin condition or if you want to see how well your immunotherapy is working. This type of test can also reveal if you have outgrown an allergy.
Results of an Allergy Blood Test
A positive allergy blood test result indicates allergy-specific antibodies were detected in your blood. This almost always indicates the existence of an allergy. An allergy blood test will tell you exactly what you are allergic to. Unfortunately, it is possible to test positive for a substance that you have never had an allergic reaction to.
A negative result indicates that your immune system probably will not respond if you are exposed to the tested allergen. Therefore, you do not have a true allergy. When diagnosing a specific allergy using an allergy blood test, your allergy specialist will use caution while evaluating the results and consider your medical history and symptoms.
Benefits of a Blood Test
The primary advantage of a blood test is that it can be performed at any time, irrespective of any pharmaceuticals you are taking. This type of test is the preferred method for testing infants and very young children. Unlike the skin prick test, only one needle stick is required for testing. If you or a loved one has an aversion to needles, a blood test may work better for you.
Types of Allergy Blood Tests
When you come into contact with an allergen, your body begins to produce antibodies against it. These antibodies instruct certain cells in your body to release chemicals that cause allergy symptoms. Immunoglobulin E, also known as IgE, is the antibody most strongly linked to your body’s allergy response.
Most allergy blood tests include the enzyme-linked immunosorbent assay (ELISA or EIA) test and the radioallergosorbent (RAST) test. The ELISA test is used to measure the amount of allergen-specific antibodies, such as IgE, in your blood. The RAST test identifies which allergens specifically trigger your allergies based on which antibodies are present in your blood.
Learn How to Breathe Easier Today
Are you sick and tired of a runny or stuffy nose, painful post-nasal drip, itchy and watery eyes and terrible sinus headaches? Learning which triggers to avoid with an allergy skin test can drastically improve your quality of life without the nasty side effects of antihistamines. To schedule your initial consultation, contact the dedicated asthma and allergy experts at Asthma Allergy Centre in Tigard, OR today. We will help you identify what is causing your allergies so you can breathe easier.