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Contact dermatitis: Diagnosis & treatment

How dermatologists diagnose contact dermatitis

To diagnose this common skin condition, dermatologists: 

  • Examine your skin, paying close attention to the rash.

  • Ask about current and past health issues.

  • Ask questions to help them determine what is causing the rash.

Finding the cause can require a bit of detective work. Your dermatologist may ask you questions about your work, free time, pets, and skin care products. Be sure to tell your dermatologist about all cosmetics you use. If you or a close family member uses a skin lightener, be sure to mention this, too.

If your dermatologist suspects that you have an allergy, patch testing may be recommended. This offers patients a safe and effective way to find out if your skin has developed an allergic reaction to anything.

What happens during patch testing?

If patch testing is recommended, the following will happen:

  1. Patches containing small amounts of substances to which you may be allergic will be applied to your skin, usually on your back.

  2. You keep the substances on your skin for a specific amount of time, usually 2 days. 

  3. You return to your doctor’s office so that the doctor can check your skin for reactions. 

  4. You may need to keep some patches on your skin for a longer time and see your doctor again in a few days.

To find out if the allergen is causing your rash, you will need to avoid that substance. For example, if the test shows that you have a nickel allergy, you may need to: 

  • Stop wearing jewelry and clothing (zippers, fasteners) that contains nickel.

  • Cover your cell phone with a case to avoid touching the metal.

  • Get a pair of eyeglasses made without nickel.

If your skin clears when you avoid the allergen, it is likely the cause of your rash.

How dermatologist treat contact dermatitis

Treatment is the same for both types of contact dermatitis.

Avoid what is causing your rash. If avoiding the cause will be difficult, ask your dermatologist for help.

For example, if you are allergic to latex but must wear exam gloves, your dermatologist can recommend another type of glove that you can wear. If you must work outdoors where poison ivy grows, your dermatologist can recommend a protective barrier cream and clothing that can help.

Treat the rash. Once you can avoid the cause, your rash should clear. To relieve your symptoms, a dermatologist may recommend the following:

  • Mild reaction: Antihistamine pills, moisturizer, and a corticosteroid that you can apply to your skin. Most patients apply the medicine twice a day for 1 week and once a day for 1 to 2 weeks. Oatmeal baths can relieve discomfort.

  • Severe reaction: If you have a lot of swelling, your face swells, or the rash covers much of your body, you may need a strong medication. Your dermatologist may prescribe prednisone. It is important to take this medication exactly as directed to avoid another flare.

    Wet dressings can help soothe skin that has lots of oozing and crusting. If your dermatologist recommends wet dressings, you’ll receive instructions to help you make these at home. 

If you have an infection, your dermatologist may prescribe an antibiotic.

Some patients need light therapy to calm their immune system. Your dermatologist may refer to this as phototherapy.

If you avoid what caused the rash, your skin will clear. Most people see clear skin within 1 to 3 weeks.

Clearing may take longer if poison ivy, poison oak, or poison sumac caused your rash. The first time you have an allergic reaction to one of these plants, the rash may linger for 6 weeks. If you get another rash, your skin should clear within 10 to 21 days.

Once your skin clears, you must continue to avoid what caused your rash.

If your rash does not clear, you should tell your dermatologist. You may need extra help.

Systemic contact dermatitis

Some people develop a rash even when they avoid touching the allergen. A rash can appear when the substance to which you have an allergy gets inside your body. The medical term for this condition is systemic contact dermatitis.

The allergen can get inside your body in different ways. You could:

  • Eat food that contains the allergen

  • Inhale or inject a medicine that contains the allergen

  • Use birth control (IUD or spermicide) that contains the allergen

While rare, some people develop a rash because the fillings in their mouth contain mercury. They could only get rid of the rash when a dentist replaced their fillings with fillings that did not contain mercury.

Trying to find everything that contains the allergen can be a challenge. Your dermatologist may be able to help you create a list of things you need to avoid. The list often varies from region to region.

Outcome for patients with contact dermatitis

By avoiding what caused the rash, most people can avoid flare-ups.

If you work with substances that caused the rash, you can still avoid a rash. Your dermatologist can recommend ways to work and products to use. More than 80% of people diagnosed with occupational dermatitis successfully manage the condition and recover without any problems.

Image used with permission of Journal of the American Academy of Dermatology: 2010; 62:1064-5.

American Academy of Dermatology. ”Contact dermatitis.” Medical Student Core Curriculum. Last update July 2011.

Hamann CR, Boonchai W. “Spectrometric analysis of mercury content in 549 skin-lightening products: is mercury toxicity a hidden global health hazard?” J Am Acad Dermatol. 2014;70:281-7.

Katta R, Schlichte M. “Diet and dermatitis: Food triggers.” J Clin Aesthet Dermatol. March 2014;30-36.

Nguyen JC, Chesnut G, et al. “Allergic contact dermatitis caused by lanolin (wool) alcohol contained in an emollient in three postsurgical patients.” J Am Acad Dermatol. 2010;62:1064-5.

Saary J, Qureshi R. “A systematic review of contact dermatitis treatment and prevention.” J Am Acad Dermatol. 2005;53:845-55.

Salam TN, Fowler JF. “Balsam-related systemic contact dermatitis.” J Am Acad Dermatol. 2001;45:377-81.

Warshaw EM, Buchholz HJ et al. “Allergic patch test reactions associated with cosmetics: retrospective analysis of cross-sectional data from the North American Contact Dermatitis Group, 2001-2004.” J Am Acad Dermatol. 2009 Jan;60:23-38

Wentworth AB, Yiannias JA, et at. “Trends in patch testing,” J Am Acad Dermatol. 2014;70:269-75.

All content solely developed by the American Academy of Dermatology

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