Patch Test

Patch Test

For whom is it done?
Patch testing should be done to patients who have skin lesions/dermatitis and:

• suspect a 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 dermatitis
• Hand dermatitis
• 6 Irritant contact dermatitis
• 6 Dyshidrotic eczema
• 6 Pustulosis palmaris et plantaris
• 6 Psoriasis limited to the palms and soles
• Seborrheic dermatitis
• Chronic tinea pedis & manus
• Nummular eczema
• Occupationally related dermatitis
• Undiagnosed cutaneous problems and erythroderma
• Special situations
• Urticaria
• Photosensitivity
• Systemic contact dermatitis

How is it 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.

What is a positive result?
Positive results are seen in sites of test as redness, swelling, little blisters or vesicle. The most common allergens to test positive in a patch test are metals, especially nickel, perfume (found in cosmetics),  paraphenylenediamine (especially in hair dyes),  rubber (underwear, gloves, glue in shoes), and chromium (cement,  tanned leather, detergents).

Life after patch testing
Avoiding the allergen that causes the reaction and the chemicals that cross react with it is the only way to eliminate
the allergy.   Your dermatologist will help you identify items that contain the offending allergen in order to avoid them. 
Substitute products that do not cause reactions.    Your doctor can make suggestions as to substitutions.  High potent topical or short term systemic steroids can treat existing rashes.   Oral antihistamines can alleviate the itching.   And moist compresses can be applied to blistered areas for a few days to promote drying of lesions.

How can The Medical City help you?
At The Medical City we have a complete roster of competent physicians who may assess and treat people with different types of allergies. For further inquiries or if you want to seek consult please call:

CENTER FOR WELLNESS AND AESTHETICS

Tel. No. (632) 988-1000 / (632) 988-7000 Ext. 6576

CENTER FOR PATIENT PARTNERSHIP
Tel. No. (632) 988-1000 / (632) 988-7000 Ext. 6444

Note:   This information is not intended to be used as a substitute for professional medical advice, diagnosis or treatment.  If you or someone you know have any of the symptoms mentioned above, it is advisable to seek professional help.