Patch Testing

Patch testing is commonly used to identify causes of allergic contact dermatitis.  When performed properly, it can be interpreted as scientific proof of allergic contact dermatitis.  The patch test does not necessarily duplicate clinical exposure in which sweating, maceration, multiple applications of a product may play roles in producing a skin reaction in real life exposure of the skin to a contact allergen..  Patch testing however is a better method of finding out a cause of an offending allergic contactant, then doing clinical trial.  If an allergen can be correlated with a known exposure, positive patch test or improvement by avoidance of substances containing the allergic contactant indentified by patch testing then the positive patch test is validated.  Unfortunately, many dermatologists as well as allergists do neglect to perform patch tests to identify the causes of allergic contact dermatitis.  At The Asthma Center, we have had decades of experience doing patch tests and identifying significant allergic contact reactions. 

This test helps to distinguish between an allergic contact dermatitis versus an irritant contact dermatitis.  The patch tests are typically read after 72 hours and in some cases 96 hours.  We have multiple different patch test materials that can be tested.  A conventional standard screen is called the T.R.U.E. test, but it detects only 65% of potential contact allergens.  There are more extensive panels of tests that have been recommended by the North American Contact Dermatitis Group that yields a more complete evaluation of patients with more relevant allergens identified.  In addition, supplemental patch tests trace can be used in unique circumstances of cosmetic-related reactions, fragrance-related reactions, hairdresser products related reactions, and metal reactions.  If a positive test is identified, then patients are given an information sheet on potential exposures to that particular allergen and potential treatment.