Unlike allergic contact dermatitis, irritant contact dermatitis--a more common type--is a nonallergic inflammatory skin reaction caused by exposure to irritating substances that actually damage the skin. Not everyone develops allergies, but everybody's skin can become irritated if abused. Contact with strong irritants, such as acid or lye, can result in blisters, erosion and ulcers within minutes or hours. For weaker irritants, such as soaps or detergents, exposure over days or weeks may be necessary before eczema develops. Any substance can act as an irritant if it is concentrated enough and if the skin is exposed to it long enough.
The eczema usually starts with a red, itchy rash and progresses to tiny blisters that ooze.
Doctors can usually distinguish contact dermatitis from other types of dermatitis by its unusual pattern. The eruption often appears with clear-cut margins, acute angles, and geometric outlines, although poison ivy and other poison plants cause lines or groups of blisters.
Though the configuration of the rash aids in diagnosis, it's not so easy to determine whether an allergy or irritant is involved. The skin reaction produced by either, especially when mild, frequently looks the same. Redness or an itchy rash may be the first sign. However, blisters that weep or form a crust, along with swelling, are more likely to appear in allergic dermatitis, such as poison ivy. As the inflammation lessens, the skin may scale and become temporarily thickened. When the dermatitis becomes chronic, the skin becomes dry, thickened and cracking.
Sometimes, if the inflammation with mild irritants continues for a long time, the original irritation disappears because the skin becomes hardened.
For self-treatment of mild contact dermatitis, a .5 percent hydrocortisone topical preparation (ointment, cream or lotion) can be applied to the skin to relieve the itchiness, redness, scaling, and swelling. Because these formerly prescription-only medications had a good safety record, FDA approved them for over-the-counter sale in 1979 on the recommendation of the Advisory Review Panel on OTC Topical Analgesic, Antirheumatic, Otic, Burn and Sunburn Prevention Treatment Drug Products. A petition to make 1 percent topical hydrocortisone drug products available for over-the-counter sale is currently being evaluated by the agency.
The labeling of the OTC products states that if symptoms worsen or persist longer than seven days, a doctor should be consulted. (Occasionally, bacterial or fungal infections superimpose themselves on the dermatitis.) The labeling also cautions against internal use and use on children under 2 years. Lubricating creams or lotions, preferably preservative- and lanolin-free, can be used to prevent cracking and dryness, especially of the hands, and the irritating factor or allergen should be avoided whenever possible.
Severe cases should be seen by a doctor. Stronger concentrations of topical corticosteroid preparations or oral corticosteroids, such as prednisone, may be prescribed. If there's a secondary infection, an oral antibiotic may be necessary.
When inflammation has gone on for a long time, an extended period of convalescence is often necessary. "I tell my patients it's like skin that's been burned after sitting on a hot stove," comments dermatologist Shelley. "You've got to allow time for the skin to heal itself."
Hope that helps!