Matthew Hall, M.D.: Patients can get allergic to various things that they are using, such as soaps, lotions, makeups, anything that contacts the skin.

DeeDee Stiepan: Nickel, which is often used in costume jewelry, is the most common allergen. So how can someone know if they're having an allergic reaction to something they're putting on their skin?

Dr. Hall: Patch testing is the crucial test that we perform to assess for allergic contact dermatitis. It's a weeklong test. We have to see patients on Monday, Wednesday and Friday of the same week.

DeeDee Stiepan: During the initial visit, the dermatologist determines possible risk factors that may be causing the contact dermatitis.

Dr. Hall: Then, based on that, we customize a panel of allergens for each patient that are placed on these aluminum discs that are taped onto the back.

DeeDee Stiepan: After two days, the patient comes back to get the patches removed.

Dr. Hall: But we also have to see the patient back on Friday because it can take 4 to 5 days before we see reactions. So it's a weeklong commitment.

DeeDee Stiepan: At the end of the week, patients are provided with a list of what they're allergic to.

Dr. Hall: We also give them access to a customized database of products that are safe for them to use that do not contain the substances that they are allergic to.

DeeDee Stiepan: For the Mayo Clinic Newsnetwork, I'm DeeDee Stiepan.

Oct. 03, 2024