Contact dermatitis is the rash that occurs when your skin comes into contact with something to which it is sensitive. (Sounds kind of obvious, huh?) Unlike hives which can come and go rapidly, a contact dermatitis rash typically takes a few days to fully blossom and can take a week or two to resolve. The classic contact dermatitis is poison ivy and many people are also sensitive to nickel from jewelry or the back of the snap on your jeans. Contact dermatitis is a distinctly different type of reaction from a true allergic reaction like wheezing, sneezing, or hives. There are no measures to desensitize people who have contact dermatitis, so identification and avoidance of triggers is the key.
The good news is there is a commercially available product that tests for the vast majority of substances that cause contact dermatitis in the general population. The method is called patch testing and the product is the True Test. Basically, these are strips of tape that are impregnated with the common contact dermatitis causing substances. They have gigantic names like p-tert-Butylphenol Formaldehyde Resin and Mercaptobenzothiazole. You wear the strips of tape on your back for a few days and peel them off to reveal, hopefully, what is causing the problem.
The bad news is that the True Test folks just issued a recall for their testing products. Apparently an important component had been left out of the test panel. They tell us it will be March before we get new patch tests, so until then we’ll have to make do with the 5 we have left that were not affected by the recall.
Good Luck True Test Guys!