Contact dermatitis is a raised, red, itchy rash that may also blister. It is caused by a delayed allergic reaction, occurring hours or even days after exposure of the skin to allergenic or chemical sensitizers.
One of the most recognizable forms of contact dermatitis, known to most of us, is the warm weather rash of poison ivy, oak, or sumac. This common rash is caused by direct contact of the skin with urushiol, the oil in the leaves and vines of these plants. Metals, such as nickel and gold, are also common skin sensitizers. The fact is that individuals can develop a contact allergy to almost any substance which contacts the skin. In many cases of contact dermatitis, the exposure to the offending chemical may occur through repeated contact to the allergen in certain jobs, such as a hairdresser who develops contact sensitivity to hair dye.
A common presentation of contact dermatitis is redness, swelling, and intense itching around the eyes. This inflammatory skin reaction of the upper and lower lids generally occurs in women and can be a recurrent phenomenon. It is thought that the skin of the lids is particularly thin and sensitive and is easily inflamed upon exposure to the many chemicals and sensitizers found in mascara, make-up, hair dyes, shampoos, soaps, and finger nail polish and/or remover, just to name a few.
Contact allergy diagnosis often requires patch testing to identify the sensitizing allergen. An allergist or dermatologist will apply small patches containing known skin sensitizers to the back. After several days it will be removed and ones skin response will be measured carefully. Many common contact allergy sensitivities can be confirmed with this test.
Researchers at the Mayo Clinic found the ten most common causes of contact dermatitis diagnosed by patch testing to be:
In the most difficult cases, a biopsy, performed by a dermatologist, may be helpful to confirm the diagnosis of contact dermatitis.
For contact dermatitis, identification and removal of the offending substance is critical for long-term resolution. Topical steroids are the treatment of choice for mild and moderate contact dermatitis. For more severe cases, a short course of an oral or injectable steroid may be recommended by your allergy specialist.