Skin testing is considered the “gold standard” for determining allergic sensitivity and is widely used to diagnosis allergic conditions. It is safe for people of all ages, including infants and older adults.
Prior to your appointment you will be asked to avoid all antihistamines and other medications that may interfere with testing. Click here to download the list of antihistamines to avoid. If you have questions regarding your medications it is advised to contact the office or your doctor for advice. On occasion you may not be able to discontinue a medication for medical reasons. In these instances, blood testing can be ordered to further evaluate allergic tendencies.
If indicated, skin testing is usually performed on the day of your initial appointment. For food, insect, and environmental allergy evaluation prick testing will be initially performed using tiny drops of purified allergen extract that are pricked into your skin (generally the forearm) with a small plastic lancet. The testing will be read in approximately 20 minutes and if positive you will experience a red, itchy hive. If testing for environmental or insect allergies are negative further evaluation with intradermal testing may be indicated. Intradermal testing involves injecting a small amount of allergen under the skin of the upper arm that is subsequently read in approximately 20 minutes. Intradermal testing can be performed for both insect and environmental allergens, but is not indicated for foods. To see if your skin is reacting the way it’s supposed to, the nurse also introduces two additional substances into your skin’s surface for a positive and negative control. All allergy skin tests are compared to the positive and negative controls.
The most common side effect of skin testing is itching and redness. This may be most noticeable during the test, when you aren’t allowed to scratch yourself. It usually subsides within a few hours, although it can persist until the next day. A mild cortisone cream can be applied to relieve the itching and redness. Rarely, skin tests can produce a severe, immediate allergic reaction. So it’s important to have skin tests performed at an office where appropriate emergency equipment and medications are available. If you develop a severe allergic reaction in the days after a skin test, call your doctor right away.