What is patch testing?
Your dermatologist may recommend you undertake patch testing if they suspect you are having an allergic reaction to one or more substances. It involves applying diluted allergens to the skin, usually on your back, and left on for 48 hours. Positive reactions can occur between 48 and 96 hours, and may appear red and possibly raised, vesicular and even a blistering area.
At St Leonards Dermatology & Laser we use a standard series of 36 allergens that are applied to our patients back.
What to expect?
Your dermatologist or nurse will place the three panels with 36 allergen patches on your back and are left on for 48 hours. During this time, you may feel itchy or sore, however we ask that you don’t remove the patches, loosen them or get them wet during this time as the results may be inaccurate. After 48 hours the patches are removed and photographs taken for review of any positive reaction. You may be asked to return in 96 hours if no reaction is visible, as some allergens take longer to react.
If the patch testing reveals allergies to one or more allergens, your dermatologist will discuss how best to avoid these and a treatment plan will be created with instructions on how to avoid what is causing your skin to react.
Your skin may be irritated from the patch test, this should clear up on its own after a few days. Your dermatologist may prescribe a steroid cream if you feel uncomfortable. It is very rare to have serious side effects to patch tests.
If the patch testing is inconclusive, your dermatologist may refer you to a patch testing clinic for a more extensive testing.