Patch testing is used to evaluate the level of allergic reaction when specific materials come into contact with the skin, which is called contact dermatitis. For instance, wearing certain jewelry may cause localized skin irritation or a specific formula of skin lotion or cleaning solution may aggravate the skin. Patches with trace amounts of the suspected agents are affixed to the skin in an unobtrusive part of the body and remain there for a few days. Dr. Lai will then remove the patches for evaluation.

There are generally two types of allergy skin tests. The first is prick skin testing where individual solutions containing the suspected allergens are placed on the skin using a prick device. The second is intradermal skin testing where individual solutions containing the suspected allergens are placed just underneath the surface of the skin using a small needle. These are not very painful procedures, and are minimally uncomfortable to the patient. In about fifteen minutes the skin will or will not react to the allergen introduced to the skin, resulting in mild inflammation that indicates a positive allergic reaction. Once the specific allergen affecting the patient is identified, Dr. Lai can discuss treatment options.

On rare occasions, about one in every thousand cases, a patient experiences a systemic allergic reaction from an allergy skin test. If this type of reaction occurs, Dr. Lai will treat the patient immediately.