What is a Patch Test?

Patch testing is a well-established method for detecting allergies to substances which come into direct contact with the skin. This reaction is known as allergic contact dermatitis . It is a form of delayed allergy because the reaction usually takes two or three days to develop.

These substances could be ingredients in your cosmetics or after- shave, jewelry, latex gloves, a skin medication you may be using, and many others.

There is a prepared test panel containing about 20 different substances on individual discs, all of which are well-known causes of contact dermatitis. These are kept in place by hypoallergenic tape. Patients may also bring in substances which they think may be causing their problem. These can be applied individually.

The patient is asked to keep the skin dry for 48 hours . Then the discs are removed and your allergist will carefully examine the test area for signs of an an allergic reaction. This reaction usually consists of a rash with swelling, redness, and tiny blisters, which are graded according to their severity.

The allergist will then tell the patient about sources of the allergen, alternative products that do not contain the allergen and other detailed information.

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