Itchy, blistering rashes on your skin may have causes other than underlying diseases, including hot or humid weather, too much sun exposure, or exposure to allergens. A patch testing procedure determines the cause of your skin rash. Sandra A. Ho, MD, and her team at Avant Allergy in Los Angeles, California, have extensive experience with patch testing and implementing appropriate treatments. If you or your child is experiencing rashes, swelling, red skin, or blistering, call or use the online booking system for an appointment today.
Patch testing involves several appointments at Avant Allergy. The first appointment involves placement of your potential chemical or contact allergens on an adhesive that the doctor applies to your clean, dry skin. You wear the patch for 48 hours, during which time you must avoid bathing, swimming, and excessive sweating to keep the skin dry.
During the second appointment, the skin patches are removed and your skin is marked as reference points for your final evaluation 72-96 hours after your initial appointment. You can bathe after the second appointment but must avoid scrubbing or itching the skin at the patch site.
At the final appointment, Dr. Ho records and analyzes the reactions to determine which allergens to avoid, and then she creates a treatment plan.
Patch tests are safe for adults and children over the age of 6 months. Most physicians recommend waiting until the child is old enough to understand not to disturb the patch site. If a child is taking medicine for their allergies, they may need to discontinue the medicine for a few days in advance of the test.
While the test itself is painless, patients receiving a patch test should expect a reaction. Positive results present as redness, bumps, swelling, or a small rash. On some occasions, the rash becomes more widespread, or you may have a reaction to the adhesive from the patches. Side effects are mild but may cause discomfort. Dr. Ho may prescribe a topical steroid after patch testing to treat any remaining symptoms.
On rare occasions, patch tests cause immediate and severe reactions. All tests are completed under physician care.
No, patch testing and skin prick tests are not the same. Patch testing detects allergic reactions to chemical and contact allergens while skin prick testing detects hay fever, hives, and asthma. Patch testing shows allergic reactions 2-4 days after applying allergens to the skin while skin prick testing for allergies with needles is read 20 minutes after the test.
To find out if you have chemical or contact allergies, call Avant Allergy today or schedule an appointment online for patch testing.