Skin Testing

1
Preparing the skin for testing

Skin testing is often performed on a person's back or forearm. The test starts by cleaning the skin with rubbing alcohol. Daniel More, MD

See the step-by-step process on how allergy skin testing is performed, from placement of the skin tests to reading the results!

How the skin is prepped for testing

 The skin is prepped for testing by allergy testing with rubbing alcohol.

2
Skin testing devices

Various skin testing devices are available. This is a multi-headed skin test device that allows five skin tests to be placed at once. The device has a small metal point that is dipped into allergen extracts, then pushed into the skin. Daniel More, MD

Skin testing devices

There are many skin testing devices for allergy testing. Many perform multiple skin tests on a single device.

3
Marking the skin

The skin is then marked with a surgical marker in order to tell which skin test site represents which allergen. Daniel More, MD

Marking the skin

 The skin is marked with a pen in order to keep track of which skin test represents which allergen.

4
Ready for skin testing

The skin is now ready to be allergy tested. Daniel More, MD

Ready for skin testing

 The skin is now ready for allergy tests to be placed.

5
Skin testing procedure

The testing device is now gently pressed against the skin, causing the allergen extracts to enter the top layer of the skin. This form of skin testing is termed "puncture," which is a variation of the scratch or prick test. Skin testing is not painful. Daniel More, MD

Skin testing procedure

 The skin test procedure involves pressing the skin test device into the skin, with metal or plastic tips puncturing just the top later of the skin.

6
Completing the skin test

The skin testing method is repeated until all skin tests have been placed. Depending on the age of the person and the reason for testing, this may range from 10 to 70 or more skin tests. Daniel More, MD

Completing the skin test

 A number of skin tests are placed, depending on the symptoms of the patient and what the allergist to trying to determine are the possible causes of the person's allergy symptoms.

7
Blotting the skin

The excess extract is blotted from the skin so that the liquid will not run into adjacent skin testing site, causing false reactions. Daniel More, MD

Blotting the skin

 Excess allergen extract is removed from the skin by blotting with paper towels.

8
Waiting 15 minutes

Once the skin tests have been placed, the results will be complete after about 15 minutes. Reactions may develop sooner than this time. Daniel More, MD

Waiting 15 minutes

A timer is set for 15 to 20 minutes, allowing time for the skin tests to react prior to reading the results. 

9
Reading the results

Positive skin test results will show a raised bump (called the wheal) with surrounding redness (called the flare). The size of the reaction determines whether the test is positive or negative. Daniel More, MD

Reading the results

 The skin test results are read at 15 minutes. A positive test shows a wheal (bump) and flare (redness) reaction. These are measured and compared to the positive and negative controls.

10
Close-up of results

The wheal and flare reaction may be of unusual shapes, indicating a strong reaction. The site may be very itchy, but the rash and itching will go away without treatment within an hour or so. Daniel More, MD

Close-up of results

 A close-up of the results show a significant positive reaction to an allergen as a result of skin testing.

11
Skin testing complete

Skin testing is now complete, and the patient is able to leave. Some allergists recommend that the patient remain in the clinic for up to 30 minutes to ensure that unexpected side effects do not occur. Side effects from skin testing are extremely rare. Daniel More, MD

Skin testing complete

 The skin test is now complete and the results can be interpreted by the allergist.

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