Allergy testing allows you and your doctor to work together to develop an allergy treatment plan based upon which specific allergies you possess. During the allergy testing process your skin is exposed to several allergens and you are observed for any signs of a reaction.
Allergy testing is particularly helpful when you have severe allergies and would like to know exactly which allergens you need to avoid, or if you have several allergies and need assistance on pinning down which cause the most severe reaction. Talking with your doctor can help you decide if you or your loved one should have allergy testing.
Why Allergy Testing is Done
Allergy testing is of great benefit when trying to establish a treatment plan to help control your allergies and alleviate symptoms. You and your doctor can evaluate the data and determine the best course of action depending on exactly what you are allergic to and how severe your allergy is.
Skin tests can help diagnose allergies to foods, latex, bee venom, penicillin and more. Allergy testing can also be used to diagnose eczema, allergic asthma and hay fever. Skin tests like this are typically safe for people of all ages including children and even infants if needed. However, your doctor may advise against skin testing in the event that you’ve had a very severe allergic reaction. Your doctor may also advise against this form of allergy testing if you are on any medications that could interfere with the test results, such as: antihistamines or antidepressants. If you have severe eczema or psoriasis that affects the testing sites then it is likely that your doctor will advise against skin testing.
For those individuals who are unable to have allergy testing done through a skin test, there are blood test options available. This type of allergy testing isn’t typically done as often as they are more expensive and because the tests done on the blood are less sensitive than allergy testing done on the skin. Skin testing is more easily able to identify allergies to things such as pollen, pet dander, dust mites, and food allergies.
Risks of Allergy Testing
Common side effects of allergy testing include swollen, red, itchy bumps which can last anywhere from a few hours to a few days, depending on the severity of your allergic reaction. Very rarely will allergy skin tests result in an immediate and severe allergic reaction but because of the possibility, it is highly recommended that any skin allergy testing is done in a location with emergency equipment and medication is available.
Preparing for Allergy Testing
Prior to testing, your doctor will ask you about your history and symptoms and how you currently treat your allergies. You will want to advise your doctor if allergies run in your family. Your doctor will also examine you for additional information. It is important to bring a list of all your current medications, both prescription and over-the-counter. Some medications can interfere with your allergy testing by either preventing accurate results or increasing your risk for a severe reaction. Your doctor may request that you stop taking specific medications for up to 10 days prior to the test. These might include prescription and over-the-counter antihistamines, antidepressants, heartburn medication or asthma medication.
During Allergy Testing
The skin allergy test typically takes about 20-40 minutes. Some tests show immediate reactions but others may show delayed reactions that happen after a few days. These are administered in your doctor’s office by a nurse. The doctor will review your test results and then discuss a treatment plan with you.
The skin prick test, also commonly called a scratch test, is the phase in your allergy testing that will check for immediate allergic reactions on as many as 40 different substances at once. Children are typically tested on the upper back, while adults are usually tested on the forearm. This form of testing is commonly used to identify allergies to pollen, pet dander, mold, dust mites and foods.
After cleaning the test site carefully with alcohol, the nurse will place a mark on your skin and apply a drop of the allergen extract to each mark. The nurse will then use a lancet to prick the extracts into the skins surface. A new lancet is used for each allergen to avoid cross contamination. The lancets barely penetrate into the surface of the skin. Because the puncture is so shallow, you will not bleed and should only feel minor discomfort.
In addition to the allergens, two additional marks will be done to ensure that your skin is having a normal reaction. One is with histamine and the other is with glycerin or saline. The histamine should trigger a response on your skin, if not, and then your skin may not be acting normally to allergens. If your skin reacts to the glycerin or saline then you may have overly sensitive skin which could result in a false diagnosis. Either way, your doctor will use this information during the interpretation phase to create an accurate diagnosis.
About 15 minutes after the allergy testing has started, the nurse will check your skin for signs of an allergic reaction. If you are having a reaction you will notice a red, itchy bump. The nurse measures these bumps and records the results before cleaning your skin.
In addition to the skin prick test, your doctor may suggest you have a skin injection test. This type of allergy testing uses a needle to inject a very small amount of an allergen extract into the skin on your arm. This is typically done to test for allergies to insect venom or penicillin.
Another form of allergy testing is a patch test. This checks to see if a specific allergen is causing you to have allergic skin irritation. These types of tests don’t use needles. The allergens are applied to patches, which are applied directly to your skin. During this form of allergy testing you will be exposed to 20-30 possible allergens including latex, preservatives, hair dyes, fragrances, metals and resins. You wear the patch for 48 hours and they are removed when you go back to your doctor’s office. It is recommended that you avoid bathing and activities that cause you to sweat during this time.
Results of Your Allergy Testing
You will know the results from the skin prick test and skin injection test before you leave your doctor’s office. If you are having a patch test done, you will need to wait a few days for results.
Your allergy testing results are measured based on the size of the bumps on your skin after you’ve been exposed to the allergen. Larger bumps indicate a more severe allergic response. If there is no bump, then it isn’t likely that you are allergic to that particular allergen.
It is important to understand that allergy testing is not 100% accurate and can sometimes indicate a false positive or false negative. You may also show an allergic response to an item during testing that does not necessarily bother you in everyday life.
Based on your results, your doctor will recommend treatment which could include medications, immunotherapy, changes in your home or work environments, or dietary changes. Allergy testing lets you retake control of your life and your allergies.