There are many ways to test to see if your symptoms may be caused by allergies. At the ENT and Allergy Center, we will help you find the right method for you.
Our center offers five main types of allergy testing to help your doctor identify what might be causing your allergy symptoms. These include:
Types of allergy testing
Skin prick testing
Skin prick testing is the most common test because of its high rate of reliability, minimal discomfort and ease of use. The test takes about 45 minutes.
Skin prick testing involves gently pressing a small plastic device dipped into different allergens onto the skin of your forearms and back. These allergens remain on the skin for 20 minutes, and then the results are read. Some patients find this test slightly uncomfortable. If you or your child prefer, we can apply numbing cream to your forearms and back one hour before the test. It does require being still and remaining in position for 20 minutes.
A positive result, or wheal, looks swollen like a mosquito bite. This swelling tells us that you are allergic to that allergen. Positive reactions usually disappear on their own within a couple hours. If needed, you can apply hydrocortisone cream to the area afterward.
Intradermal testing is performed on the upper arms by placing a small amount of allergens in two different strengths just under the skin with a very tiny needle.
We apply a weaker dilution first, wait 10 minutes and then read the results. If the patient does not react to the first dilution, a second stronger dilution is applied. After another 10 minutes, the results will be read again. An official copy of the result is provided to the patient. This test takes about 60 minutes and usually requires two appointments.
Patch testing is used to determine possible allergens that cause a reaction on the skin. This kind of allergic reaction usually causes redness and itching. This involves placing panels or patches of substances to which you may be allergic on the upper back. We may use other areas depending on how many patches are applied, if skin is not suitable, etc.
Among these substances are common allergens like:
Preparing for patch testing
It’s important to keep your skin in good condition prior to patch testing as it helps ensure accurate results. There are a few ways in which you can prepare your skin:
- Avoid sun exposure for one week before your appointment.
- Avoid topical medicines such as creams and ointments where the patches will be placed.
- You may use moisturizers on your skin until the day before patch testing.
- Antihistamine use before and during the test is permitted.
- No steroid use (oral or topical)
During patch testing
The patches remain on your back for 48 to 72 hours. It’s important that you do not apply anything to the patches, keep the patches dry, avoid itching or rubbing the patches, and avoid physical activities that might loosen the patches. It’s also helpful to avoid direct sunlight to the patch area, and reducing hot areas and activities that might interfere with the patches. It is ok to take prescribed medications as usual, excluding steroids.
During this time period, do not shower or take a bath. Our dermatologists recommend washing areas of the body with a washcloth where the patches are not located. It is important to continue following these instructions after removing the patches. You must continue following instructions until after you have seen your provider for the final reading.
Not every allergen will react positive, so you might be allergic to a percentage of the allergens we test. It’s also possible you will be asked to come back again in a few days to read any results that might not have reacted in this short timeframe.
Once allergens are identified, our team will work with you to create a personalized treatment plan. You might be seen by both a dermatologist and an allergist at our ENT and Allergy Center of Missouri. We’ll also make sure our team updates your primary care doctor. Thanks to being part of an academic health system, that’s just one way we’re able to provide you with the best care possible.
Penicillin allergy testing
The ENT and Allergy Center can provide skin testing and oral challenges for patients with a penicillin allergy. Many patients spend long periods of time labeled as allergic to penicillin, and this can complicate the treatment of bacterial infections, increase surgical costs and potentially promote antibiotic resistance. Correctly identifying those who are not allergic to penicillin and removing the stigma of penicillin allergy has many benefits for the patient.
If you would like to undergo evaluation for penicillin allergy testing, the first step is to schedule a consultation with one of our allergy providers. This will help determine if you are an appropriate candidate to undergo skin and oral challenge testing.
The skin testing portion consists of a patch test and then, if negative, an intradermal test. Skin tests take about an hour and catch the majority of patients who are allergic to penicillin. If both skin tests are negative, a two-hour oral challenge is given. Be prepared to be in the office for potentially four hours without food or drink except for water. Before you leave our office, we will ensure you can safely take penicillin and amoxicillin. Both you and your doctor will be given a copy of the test results at the end of your appointment.
In instances where skin prick and blood tests do not provide a definitive diagnosis, your allergist might suggest an oral challenge. This is a highly accurate diagnostic test for food allergy.
Risks of allergy testing
Though extremely rare, the most serious reaction that can occur with skin testing is anaphylaxis. This is a major allergic reaction that can include:
- Chest tightness
- Lip swelling
- Throat swelling
- Or a more extreme reaction
Allergy testing cannot be done if any of the following apply:
- You are taking an antihistamine, beta-blocker, tri-cyclic antidepressant, natural medicine or other medications that can affect the test results. Contact the ENT and Allergy Center at 573-817-3000 for a complete list.
- Your spirometry test is low.
- You have asthma and your asthma has been worse lately or is not in good control.
- You have chest pain or unstable angina or have had a recent heart attack.
- You have a cold or upper respiratory infection, and/or a temperature over 99.6.
- Your skin is overly reactive and may give false positive results.
- You are pregnant or breastfeeding.
- You are wheezing or short of breath.
If allergy skin testing is not appropriate for you, blood testing may be an option.