Patch Testing
Patch Testing is recommended for patients whose rashes are suspected to be the result of allergic reactions to chemicals that have come into contact with the skin. It consists of the application of a series of many chemicals to small areas of the skin, most often the back. This is followed by a period of observation, usually 2 - 4 days, to determine if rashes develop at the sites of contact. To maximize skin contact and absorption, an occlusive (sweat producing) dressing is applied over the application sites and taped into place.
Allergy
Allergy is an individual's specific adverse reaction upon exposure to a chemical to which most individuals do not adversely react. The exposure can be through skin contact, inhalation, ingestion or injection, and thus can affect the skin, nasal mucous membranes, lungs and other organs. An allergic reaction cannot occur upon the initial exposure to a chemical, only upon a subsequent exposure. It may develop upon the very next exposure, or may not develop until many exposures have occurred. Once an individual becomes allergic to a chemical, however, an adverse reaction will occur with each and every subsequent exposure.
Allergic Contact Dermatitis
Allergic Contact Dermatitis is a rash that develops as a result of an allergic reaction to a chemical to which the skin is exposed.
Unfortunately, it is not always apparent that a rash is a result of an allergy, and even if an allergy is suspected, it is often not apparent which specific chemical is responsible. It usually takes a good amount of detective work by both patient and physician. Patch testing is the cornerstone of this investigative process.
Choosing the Right Chemicals
Choosing the Right Chemicals with which to test is of utmost importance. Since we are exposed to hundreds of chemicals on a daily basis, how do we determine which chemical allergies to test for? Fortunately, although any chemical can theoretically induce an allergic rash, most do not commonly do so. Experts in the field of contact dermatitis have, over the several past decades, painstakingly researched this issue and have determined which chemicals are the most common offenders.
The approximately 80 patches that we have chosen to apply in our panel contain most of these. It is an expanded version of the panel of allergens recommended by the North America Contact Dermatitis Group (NACDG), a universally respected source of information regarding contact dermatitis.