Patch testing is a process used to assist in detecting contact dermatitis due to an allergic reaction. Patching can identify which substances that one has come in to contact with that may be causing a delayed allergic reaction. There are no needles or blood testing involved.
Patches with allergens are placed in groups on the back. Allergic reactions typically appear within 2 to 4 days after the allergen is applied to the skin, but can take up to a week in some cases. Allergens that are applied to the to the skin are tailored for each individual and their needs. There are 3 to 4 appointments that must take place. The first appointment includes applying the patches, the second appointment is for removing the patches, and the third appointment is for the readings. Some individuals may need a fourth appointment a week to ten days later for a late reading of results. The test itself is painless and simple.