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Contact Dermatitis

What is contact dermatitis?

Contact dermatitis is what happens when skin develops a rash due to contact with an external substance. This can happen because of a true allergy to the substance or simply because the substance is irritating to the skin--or a combination of both of these factors. The rash can appear shortly after contact with the substance, but usually it does not appear until a couple of days later and can last for several weeks to months. The substance can sometimes be something you have used for years. Identifying and avoiding allergens (substances that can cause allergies) and irritants is the best treatment for contact dermatitis. 

The Contact Dermatitis Clinic at Tufts Medical Center is dedicated to helping patients identify and manage their contact allergies. The best way to do this is through a process called patch testing. 

What is patch testing?

Patch testing is a non-invasive form of allergy testing, different from the prick testing that is performed for food and environmental allergies. Instead, patch testing evaluates for allergies to things like fragrances, dyes, preservatives, rubber, metals, topical medications, sunscreens, certain plants, and more.  Patch testing can be done in children but is typically avoided in pregnant or nursing women.  

During patch testing, multiple "patches" containing different potential allergens are placed on the skin, marked and left on for 48 hours (usually about 80 to 100+ allergens will be taped to your back with hypoallergenic tape). The skin is then evaluated or "read" for allergic or irritant reactions. Because the rash of contact dermatitis can sometimes take several days to develop, patch testing typically requires three office visits: 
  1. Monday: Initial evaluation and patch placement (Doctor visit)
  2. Wednesday: Patch removal and first "read” (Nurse visit)
  3. Friday: Second "read" and education about final results (Doctor visit)
After patch testing, a detailed letter will be sent to your referring provider with your results and suggested treatment strategies.  

To make the patch testing processes as smooth as possible, we ask that you follow the steps below prior to your visit:

1. Please carefully review the Patch Test Guide

2. Please fill out the Patch Test Patient Form and return it to us TWO WEEKS before your visit.  

At your first visit, your doctor will ask you a lot of questions about your rash, your life and the products that you use to help determine what allergens to test you to.  Filling out this form carefully in advance allows both you and your doctor to start thinking about potential causes of your rash.  

3. Please gather any products that you think may be responsible for your rash and bring them to your FIRST as well as your THIRD/FINAL patch test visit.   

At your first visit, we may be able to personalize your patch test to include the products you bring in. At your third/final visit where you get your patch test results, we may look at your products and their ingredients again to see if any of them may be the source of your rash.  

Examples include: makeup, lotion, gloves, clothing, shoes. If you are bringing essential oils, please bring them in whatever dilution you typically use them. 

4. If you have been patch-tested before, and/or have been biopsied outside of Tufts Medical Center, please ask your doctor for your results so that we may review them.  
It may also be helpful to bring paper copies with you to your visit.  

Please have previous patch test and biopsy results and your Patch Test Patient Form faxed to us at 617-636-9169.   

Clarissa Yang, MD

Clarissa Yang, MD

Title(s): Chief of Dermatology; Dermatologist; Harvey B. Ansell Professor of Dermatology and Chair, Tufts University School of Medicine; Assistant Professor, Tufts University School of Medicine
Department(s): Dermatology
Appt. Phone: 617-636-0156
Fax #: 617-636-9169

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