Patch Testing checks for chemicals that cause a delayed reaction, such as contact dermatitis. This test is performed by placing a safe, chemical patch on the person’s back. In order to have the patch placed on, patients should properly clean the skin and be freshly showered. No rubbing alcohol should be used in the cleaning process, and the patch will not be able to be properly placed if the subject is still wet. It the tape peels off, the entire process will have to be repeated. This patch stays on the skin for two days before being removed to be examined. It is again examined three to four days later to make sure nothing new has developed. The test is considered positive if blisters, bumps, or swelling develops. When you are preparing to have this test done, you should avoid taking any systemic immunosuppressants or oral steroids up to one month before, and topical steroids should not be used on the area of the skin that the patch will be placed one week before having the test done. Any use of inhaled steroids, leukotriene receptor antagonists, or antihistamines are still allowed to be used.