Contact dermatitis is a skin allergy that occurs when an allergen comes in direct contact with the skin. Poison Ivy is probably the most well-known and frequent contact allergen, but the skin can develop sensitivities to various chemicals including preservatives, fragrances, metals, rubber, dyes, and even medications like steroids, antihistamines, and antibiotics used to treat skin diseases. Contact dermatitis presents with the classic findings of inflammation in the skin: redness, swelling, blistering, scaling, and itching. Unlike urticaria, which come and go over hours, contact dermatitis typically persists over weeks.
Contact dermatitis can be diagnosed with patch testing where a series of patches impregnated with allergens are taped to a patient’s back and left in place for forty-eight hours. When these patches are removed, the physician looks for an inflammatory reaction that would indicate a positive reaction to a particular allergen. Patients are then counseled and educational materials are reviewed to educate them about where particular allergens are found and how to avoid them. Education alone can have profound effects, offering a potential cure for patients with chronic dermatitis that has been triggered by a contact allergy.
Topical steroids are the main treatment for active contact dermatitis, while more severe cases can warrant a few weeks of oral steroids. The American Academy of Dermatology has additional resources to help patients deal with their contact allergies and identify offending products.