skinprick

Skin prick test, often called prick testing, is a diagnostic procedure used to detect IgE-mediated sensitization to specific allergens. It is widely used to evaluate suspected environmental allergies, such as pollen, dust mites, pet dander, molds, and some foods, and to guide management of allergic rhinitis, asthma, and atopic dermatitis.

In a typical test, standardized allergen extracts are placed as small drops on the skin, usually on the forearm or back. The skin is then pricked or pierced with a sterile lancet so the allergen enters the superficial layers. A histamine control and a negative control are included. After 15 to 20 minutes, raised wheals and surrounding redness are measured.

Interpretation: A positive reaction indicates sensitization to the tested allergen, but it does not guarantee a clinical allergy. Result thresholds vary by allergen and patient factors. The test can identify candidates for avoidance strategies or immunotherapy, but false positives and negatives occur. Results should be integrated with history and, when appropriate, supervised oral food challenges.

Safety and limitations: Skin prick testing is generally safe with minor local reactions being common. Rare systemic reactions can occur, so testing should be conducted in settings equipped to treat anaphylaxis. Antihistamines and some medications can affect results; patients are usually asked to avoid them for several days before testing.

Alternatives: Serum-specific IgE tests (blood tests) may be used when skin testing is impractical or contraindicated. These tests measure circulating antibodies rather than skin reactivity.