fragrance, or household chemicals.
Contact allergy does not usually manifest as an immediate life-threatening reaction.
Rather, it is usually a slower process in which the immune system reacts against certain chemical substances.
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In these reactions, allergic antibodies are not usually produced against the contact allergen.
The back is usually the area of skin where the patch test is performed.
The patch consists of a variety of different allergens which are applied in little dots on an adhesive sheet.
After 48 hours, the patches will be removed at the doctor’s office.
Before doing so, the location of each patch will be marked with an indelible surgical marker.
This will provide the doctor with a reference when you return to the office for a final evaluation.
The final evaluation is usually performed 96 hours after the initial placement.
Patch testing is painless and, unlike allergy tests, does not involve needles of any sort.
Children can be tested once they are old enough to understand that the patches cannot be removed.
A positive test may show redness, bumps, mild swelling, or even form a small blister.
Some reactions may be uncomfortable but are typically mild.
Keep in mind that there are limitless numbers of patch tests that can be performed.
The standard panels include 30 or more items.
If the initial patch test panel is completely negative, additional panels may be recommended based on your history.
Lazzarini R, Duarte I, Ferreira AL.Patch tests.An Bras Dermatol.
