Contact Dermatitis

Our contact dermatitis clinic determines whether contact allergies cause rashy skin problems. This clinic can play an important role in the evaluation and management of eczema.

Contact dermatitis is when your skin reacts from direct contact with potential irritants or allergens such as:

  • Chemicals that are present in everyday products
  • Fragrances and preservatives
  • Metals

The skin rash, a form of eczema, starts at the site of contact but can spread to other areas of the skin. The red and itchy rash can get worse with continued contact with the irritant or allergen.

What to expect at your appointment

At your first visit or telemedicine consultation, we ask you questions about your rash history and exposures, such as your:

  • Hobbies
  • Personal care products
  • Work

We examine your skin of the affected areas and perform a skin biopsy if needed.

Patch testing for contact dermatitis

At your visit, we use a method called patch testing to identify potential causes of your dermatitis. We place a series of patch testing allergens on your back. We use overlying tape to ensure the patches stay in place and achieve good contact.

Initial patch test reading

At your follow-up visit, we remove and read your first patches. Many of the substances may take longer to develop a reaction. So, we take a final reading 2 to 7 days after we've completed the patch placement.

Final patch test reading

During your final visit and second patch test, we read your tests and assign the strength of reactions to potential allergens.

We have an in-depth conversation with you about any positive reactions. We also give you a handout which details the possible locations of the allergens.

If appropriate, we assign you an ID from a personalized CAMP (Contact Allergen Management Program). This program allows you to find safe products to avoid allergic reactions.

Contact dermatitis frequently asked questions

Are the products I've been using for years potential allergens?

Yes. You may get allergic contact dermatitis from ingredients in the products that you have been using for years on your skin.

How long are patches left on and can I shower?

We apply patches on your back on Mondays and then take them off on Wednesday for the first reading. Unfortunately, you cannot shower for the week that the patch testing occurs.

If you have a detachable showerhead, you can shower around the patches and the areas where we applied the markings.

Should I avoid certain medications before patch testing?

Yes, two weeks before patch testing, you should avoid taking:

  • Oral steroids
  • Immunosuppressing agents, such as cyclosporine

Other medication guidelines

If you have received a steroid shot, you should wait at least a month before patch testing.

If you start a new medication before patch testing, please call us before we perform the patch testing to make adjustments. Otherwise, the patches will not be accurate on these medications.

It is okay to take antihistamines during the test week, such as:

  • Allergra
  • Claritin
  • Diphenhydramine (Benadryl)

What happens if I have a positive patch test?

You will develop an itchy, red, raised rash, about the size of a dime, over the positive test site.

We will discuss your positive patch test results in the context of your situation and determine if they are relevant. Then, we'll create a CAMP list of safe products personalized to your skin allergies to avoid further allergic contact dermatitis.

Patch testing resources

For more information about patch testing, please refer to the following resources:

Appointments and referrals

We provide services in Lebanon, New Hampshire. We typically schedule appointments on the following days:

  • Monday, Wednesday, and Friday
  • Initial patch applications: Monday mornings
  • First and second patch testing reads are the following Wednesday and Friday

Appointments to our clinic are by referral only. Please contact your dermatologist, allergist, and other physician to obtain a referral.

Contact Dermatitis providers

Before your visit, we review the information sent by your referring provider. We try to identify potential allergens and the need for supplemental patch testing panels.

Jonathan S. Glass, MD


I pursue providing the highest quality care in a friendly, professional clinic. My experiences in global health, US military service, and in clinical care have taught me the value of pro… Read more

Areas of focus


  • Lebanon

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