CHILDREN’S ALLERGIES: SKIN TESTS FOR CONTACT DERMATITIS
A patch test is performed if a careful history (based on the site of the lesion) offers a clue to the offending agent. The gauze used in testing (which is soaked in the suspected material) is left on the skin for forty-eight to seventy-two hours.
The causes of contact dermatitis include the following materials:
Soaps and detergents: May irritate the hands, fingers, or wrists.
Plants: May touch the hands, forearms, ankles, etc. and create an itch usually followed by a secondary bacterial infection. (Examples include poison ivy, poison sumac, English ivy, and philodendron, as well as such plant derivatives as Japanese lacquer and cashew nutshell oil.)
Textiles: May cause contact allergy where the pressure of the clothing is greatest, such as under a hat band.
Jewelry: May cause contact dermatitis on earlobes, neck, and wrists.
Cosmetics: May cause contact dermatitis on eyelids, ears, fingers, etc. If the dermatitis is present in the scalp, the cause may be scalp lotions, hair tonics, hair dyes, or shampoos; if it is on the eyelids, the cause may be mascaras and eyebrow pencils; if it is in the armpits, the cause may be deodorants.
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