Patch testing

What is Patch Testing?

PATCH TESTING is a safe and easy way of identifying whether a substance that comes in contact with the skin is causing an allergy.

Patch testing should be done to patients who have skin lesions/ dermatitis or any of the following conditions:

• Suspect specific antigen or substance
• A history and distribution of the rash highly suggestive of contact dermatitis
• Other dermatitides that flare or do not respond to treatment
• Atopic eczema
• Stasis Dematitis
• Hand dermatitis
• Seborrheic dermatitis
• Chronic tinea pedis & manus
• Nummular eczema
• Occupationally related dermatitis
• Undiagnosed cutaneous problems and erythroderma
• Special situations
• Urticaria
• Photosensitivity
• Systematic contact dermatitis

How it’s done:

A dermatologist will take a detailed history of the materials that your skin often comes in contact with at work and at home to try to identify the possible allergen. A thorough examination, particularly the distribution of the rash, may help identify the possible culprits. A patch test is then done to determine the allergen, particularly when the clinical history and the physical exam are non specific.

Patch tests are safe and easy way to diagnose different contact allergens. Small amounts of a possible common allergen are applied to your skin on specially designed chambers and then removed after two days. During the next 48 hours, you must not shower, perform hard work or exercise that will result in sweating. If the test patches get wet, they may fall off, resulting in test failure. In two days, the dermatologist will remove the chambers for the 1st reading.

You will be asked to return the next day for a 2nd reading. You may develop itching under specific chambers. Pruritus or itch is an indication of a positive response, and scratching may alter the test reading. Application or intake of steroid medication and sun exposure of the test area must be avoided during the test period.