Skin Testing for Allergies in Melbourne, FL

Allergies Tested for in a Skin Test

Skin testing for allergies is considered the primary diagnostic technique for many allergies including:

• Allergic asthma, rhinitis, and conjunctivitis
• Food allergies – With some foods, only half of all positive tests are true positives. Test results may need further confirmation with a food challenge.
• Some medication allergies – Skin testing has been validated and standardized for the evaluation of some medication allergies. This is true for penicillin allergy skin testing. However, skin testing is not well-defined for other antibiotic and drug allergies.
• Venom allergies to wasps, hornets, bees, yellow jackets, and fire ants

Methods for Skin Testing For Allergies

Skin Prick or Puncture

The skin prick or puncture technique involves applying liquid droplets of a concentrated allergen extract to the surface of the forearm or upper back. Both positive controls known to elicit a reaction and negative controls are applied. Your allergist will then make a tiny prick through each drop on the surface of your skin. If you are allergic to any of the substances, a raised and red bump, called a wheal and flare, will appear within 15 to 20 minutes of the skin prick. The diameter of the wheal and flare test is compared to the controls to determine if there was a true allergic reaction.

Skin prick testing is sensitive, but not very specific. A positive allergy skin prick test is accurate less than 50 percent of the time. However, a negative allergy skin test is 95 percent accurate in confirming the absence of an IgE-mediated allergy. Therefore, a false-negative allergy skin test result is uncommon.

Skin Prick-by-Prick Testing for Food Allergy

Intradermal Skin Test

The intradermal skin test method involves injecting a small amount of allergen extract directly under the surface of the skin through a needle. Just like a skin prick test, a negative control without any allergen extract is also injected for comparison purposes. The diameters of any resulting red bumps, known as wheals and flares, are measured to determine if there was a positive allergic reaction.

Intradermal allergy skin testing is typically performed when a prick or puncture test comes back negative but your doctor still believes you may be allergic to a particular substance. Because intradermal skin testing is highly sensitive, it is optimal for detecting venom allergies. However, intradermal skin testing is unacceptable for testing food or latex allergies due to the possibility of severe systemic reaction.

Because intradermal skin testing is more sensitive, there may be many small, positive reactions that are not clinically significant. This equates to more false-positives. Additionally, with intradermal skin testing, there is a higher risk of inducing a systemic allergic reaction, so prick or puncture testing is usually recommended prior to intradermal testing. This is especially true when testing for airborne allergens.

Skin Patch

Allergy Skin Testing Side Effects

The wheal and flare test reaction, characterized by a raised and swollen bump surrounded by redness, often begins to resolve within an hour.

Anaphylaxis is rare but can occur during skin testing. It is almost always associated with intradermal testing without prior prick or puncture testing.

Who Can Benefit from Skin Testing For Allergies