What to Expect During Allergy Testing

Skin Testing

Skin testing is the oldest and most reliable form of allergy testing. It is a safe and fairly easy way for your doctor to figure out or confirm what’s causing your allergy symptoms.

Tell your doctor about all medicines you’re taking, including over-the-counter products. Some drugs can interfere with the results, so your doctor should know what you are taking in order to tell you which medications to avoid before the test.

• Testing begins with a prick, puncture or scratch method, which involves the placing a drop of the allergen in question (usually a commercially available extract of pollens, molds, foods, pet dander, etc.) on the skin and scratching the skin with a needle. This testing is not painful, and generally there is no bleeding involved since the needle only scratches the surface of the skin.
• After the skin is scratched, the test takes about 15 minutes to develop. There may be many skin tests performed, depending on the person’s age, symptoms and other factors.
• A positive skin test appears as a raised, red itchy bump, similar to a mosquito bite.

Intradermal Test

If the prick skin test results are negative, but your history suggests that these results should be positive, an intradermal skin test can be performed. Testing involves the injection of a diluted allergen extract under the top layer of the skin with a needle. Again, a reaction will result in a raised, itchy bump.

Patch Test

Your doctor could put an allergen on a patch and then stick that on your arm or back for 14 to 72 hours.

Blood Test

Blood tests are not as sensitive as skin tests but are often used for people who are not able to have skin tests.

Reactions to skin testing are rare, but let your doctor know right away if you have:

• Fever
• Lightheadedness
• Trouble breathing
• A widespread rash
• Swelling on your face, lips, or mouth
• A hard time swallowing