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Prick skin testing and intradermal skin testing are relatively fast methods of identifying allergies. The results of these types of testing are available within 15 to 20 minutes after the tests are applied. Both prick skin testing and intradermal skin testing are commonly used to determine what you are allergic to, as well as the severity of the allergy.
Please follow these directions when getting ready for these tests. Check with your/your child’s doctor before you stop medications. All antihistamines will affect the results of these tests and need to be stopped before the testing is performed. If the medicine is not stopped before the test, we will not be able to get accurate results.
Stop these antihistamines for 5 days before your appointment:
Stop these oral antihistamines for 3-4 days before your appointment:
If you are taking an oral antihistamine that is not listed, stop the medicine for 3-4 days before your appointment. If you are not sure if the medicine you are taking is an antihistamine, ask your doctor. Some over-the-counter cold and flu medications contain an antihistamine, so be sure to read labels carefully.
Stop These Medicines The Morning Of Your Appointment:
Continue to take all your other medicine as you usually do. Inhaled, nasal and oral glucocorticoids (steroids) will not interfere with the results of your skin testing.
Do not apply lotions or creams to your back the day of your appointment.
When prick skin testing is done, a small amount of each thing you may be allergic to (allergen) is placed on the skin (usually your back). The skin is then pricked with a small plastic pick. If you are allergic to an allergen, you will get a bump and redness where the skin is pricked. After a short time (15 minutes), each skin test reaction is measured for swelling and redness. A positive reaction indicates that you may be allergic to that allergen. Your doctor will compare your prick skin test results with your history of symptoms.
Allergy skin testing often takes up to 90 minutes to complete.
When intradermal skin testing is done, a small amount of each thing you may be allergic to (allergen) is injected under the skin. Like prick skin testing, if you are allergic to an allergen, you will get a bump and redness where the allergen was injected. After a short time, each skin test reaction is measured. A positive reaction indicates that you may be allergic to that allergen. Your doctor will compare your intradermal skin test results with your history of symptoms. A combination of the prick and intradermal testing can give an idea of the relative severity of the allergy.
Patch skin testing can be used to find out if a rash is from direct contact with an allergen. Generally, the nature of this type of reaction is slower to develop which is why patch testing requires 3 sequential visits for completion.
Please follow these directions when getting ready for this test. Check with your/your child’s doctor before you stop any medicine. If certain medications are not stopped before the test we will not be able to complete the test. These include the antihistamines listed above for skin testing. If you are not sure if the medicine you are taking is an antihistamine, ask your doctor. Some over-the-counter cold and flu medications contain an antihistamine, so be sure to read labels carefully.
Additionally:
You will visit us a number of times during patch testing. The patch tests are placed during the first visit. Patch tests include two or three rectangular panels (approximately the size of a 3” x 5” card) with small amounts of pre-applied allergens. Sometimes individual patch tests may be applied. The tests are placed on the skin, typically the back. The panels also have acrylic tape as part of the panel. This will help the panels adhere to the skin for two days. After two days the panels are removed and the skin reactions are measured. You will come back again one or two days after the panels are removed to measure the skin reactions again. We will provide you with information regarding the results at the final visit.
Skin testing for venom allergy (bees, wasps, hornets and fire ants) involves both prick skin testing and intradermal testing. There are a series of skin tests performed with venom testing so the duration of testing will be a little longer than with other types of allergy skin tests.
Please follow the directions described under the Allergy Skin Testing section with regards to stopping medications.
Testing for venom allergy after a “bee sting” involves both prick and intradermal skin tests. If indicated, fire ant allergy can also be tested in this manner. Testing to the following venoms is performed in all patients reporting a possible bee sting allergy: honeybee, white-faced hornet, yellow-faced hornet, yellow jacket and wasp. First, prick skin testing is performed to each of the venoms then, intradermal testing is performed. If there is a positive reaction to any venom, then testing for that venom stops. A positive reaction indicates that you may be allergic to that venom. Your doctor will compare your skin test results with your history of symptoms. We may also order blood testing to further investigate for venom allergy.
Venom allergy skin testing usually takes 90 minutes to complete.
Skin testing for penicillin allergy involves both prick skin testing and intradermal testing. There are a series of skin tests performed with penicillin testing so the duration of testing will be a little longer than with other types of allergy skin tests
Please follow the directions described under the Allergy Skin Testing section with regards to stopping medications.
Testing for penicillin allergy starts with prick skin testing to penicillin and a related medication called PrePen. After prick skin testing, intradermal testing is then performed with each of the substances. If there is a positive reaction to any of the tests, testing stops. A positive reaction indicates that you are most likely allergic to penicillin. If all skin testing is negative, in the final step of your evaluation you will be given amoxicillin in the clinic and observed closely for any reaction.
Penicillin allergy testing usually takes about 90 minutes to complete.