Dermatology New York

Contact Dermatitis

Allergic contact dermatitis is an extremely itchy rash that develops when someone comes into contact with a substance to which he or she is allergic. These substances (allergens) are harmless to most people but trigger immune reactions in those who are sensitive. Only a small amount of the allergen is required to trigger an allergic reaction.

The image below is an example of contact dermatitis from a nickel allergy (click for a larger view).

Nickel allergy from buttons or belt

Repeated exposures to an allergen are required to develop an allergy. Most people might be exposed to an allergen for years before finally developing an allergy. Once allergic to a particular substance, the person usually remains allergic for life.

After exposure to an allergen, the skin may appear red, swollen, and blistered, or dry and bumpy. The location of the rash helps to determine the source of the allergy since it develops where the allergen contacts the skin.

For instance, a rash on the neck or wrist may suggest an allergy to the metal found in a necklace or wristwatch. Rashes on both feet may be due to chemicals found in the leather or rubber of shoes.

In severe cases, the rash may extend beyond the point of contact and appear elsewhere in the body.

The focus of treatment is avoidance of the allergen (the substance that causes the allergy).

Common allergens include:

  • Plants (poison oak, poison ivy)
  • Metals, particularly nickel. Nickel is found in jewelry (earrings, watches, necklaces), buttons (inside portion of jeans), or belt buckles
  • Fragrances (including those found in lotions, shampoos, and other cosmetics)
  • Preservatives (found in lotions, or leather and other fabrics)
  • Rubber (gloves)
  • Hair dyes
  • Glues
  • Medications (Neosporin)

The rash of contact dermatitis may start as soon as several hours after contact with the allergen. And it can take days to weeks to heal even after the allergen is removed from the skin.

If the cause of the allergic reaction is uncertain, your doctor may run an allergy test. The suspected allergen may be applied several times a day to a small patch of sensitive skin (such as the inner arm) for several days. The area is then monitored for changes.

Your doctor may alternatively perform an in-depth history, determining the type of substances you encounter, and suggest patch testing.

Contact dermatitis might be treated with one or more of the following:

  • Moisturizers, to heal damaged skin and provide a barrier
  • Topical corticosteroids
  • Oral steroids, used for a short period for severe cases
  • Topical immunomodulators (Elidel, Protopic)

Your doctor will recommend a treatment plan best suited to your needs.


Image courtesy of DermAtlas, ©2001-08

This information is for general educational uses only. It may not apply to you and your specific medical needs. This information should not be used in place of a visit, call, consultation with or the advice of your physician or health care professional.

Communicate promptly with your physician or other health care professional with any health-related questions or concerns.

Be sure to follow specific instructions given to you by your physician or health care professional.