There are many ways to test to see if your symptoms may be caused by allergies. There are three types of allergy skin testing that help your doctor identify what may be causing your allergy symptoms, including:
- Skin prick testing
- Intradermal testing
- Patch testing
The ENT and Allergy Center of Missouri offers allergy testing on people ages 3 and older.
Allergy skin prick testing
Skin prick testing (SPT) is the test most allergists choose for their patients because of its high rate of reliability, minimal discomfort and ease of use. The SPT test takes about 45 minutes.
SPT testing involves gently pressing a small plastic device dipped into different allergens onto the skin of your forearms. These allergens remain on the skin for at least 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 one hour before the test.
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, we can apply anti-itch cream to your arms afterward.
Allergy intradermal testing
Intradermal testing (IDT) is performed on the upper arms by placing a small amount of 20 allergens in two different strengths just under the skin with a very tiny needle.
IDT takes about 90 minutes total, and we read your results after 20 minutes. This test usually requires two appointments.
Allergy patch testing
Patch testing involves placing three tape-like panels or patches of 29 substances to which you may be allergic on the upper back.
Among these substances are common allergens like:
The patches remain on your back for 48 to 72 hours. You cannot get the patches wet during this time.
When the patches are removed, the results are read by our staff and read again 48 hours later to look for any delayed reactions. Individual tests of suspected allergens can be applied to your back the same way as the patch tests.
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.
Skin tests take about an hour and catch the majority of patients who are allergic to penicillin. If skin tests are negative, a two-hour oral challenge is given. 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 of Missouri at 573-817-3000 for a complete list.
- Your airflow screening test, called a peak flow 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.