Pricktests

Skin prick testing, also called prick testing, is a diagnostic procedure used to identify immediate, IgE-mediated allergic sensitizations to a range of substances such as pollens, dust mites, animal danders, foods, venom, and certain medicines. It is commonly performed to evaluate suspected allergies in individuals with nasal congestion, asthma, hives, or food-related reactions. A positive test supports sensitization to a substance, which may or may not correspond to a clinical allergy.

During the procedure, small amounts of standardized allergen extracts are placed on the skin, usually on the forearm or back. A sterile lancet or needle is then used to gently pierce the superficial skin, introducing the allergen into the epidermis. A positive control (histamine) and a negative control (saline) are included to gauge skin reactivity. After about 15 to 20 minutes, the test sites are inspected. A wheal (raised bump) surrounded by a flare is measured; a positive result is typically defined as a wheal that is at least 3 millimeters larger than the negative control, though criteria can vary by institution and allergen.

Interpretation of results requires clinical correlation. A positive prick test indicates sensitization but does not prove that the allergen will cause symptoms in daily life. Factors such as patient history, timing, and exposure are essential for accurate diagnosis. Prick testing is generally safe when performed by trained personnel, but it can cause local itching or swelling and rarely a systemic reaction. Antihistamines and some other medications can suppress test results, so appropriate withholding or scheduling is important. Alternatives include serum-specific IgE testing and oral food challenges, depending on the clinical context.