Allergies and Hypersensitivities - Skin allergies

Allergies affecting the skin take many forms, the most common being eczema, urticaria (hives), angioedema (swelling of the subcutaneous tissues), and contact dermatitis. Among the most common causes are foods, cosmetics, fabrics, metals, plants and flowers, plastics, insecticides, furs and leather, jewelry, and many industrial chemicals. Studies of patients who seem to be especially sensitive to skin allergies show that they have higher than average amounts of a body protein called immunoglobulin E in their systems.

Contact dermatitis usually is distinguished by skin swelling, hives, or blisters. The area affected is usually the skin that comes in direct contact with the allergen, so a watch band allergy response will appear as a band around the wrist where the watch-band touches the skin. Long-term exposure will cause dry, cracked, darkened patches on the skin.

Poisonous Plants

Poison ivy, poison oak, and poison sumac contain an extremely irritating oily resin that sensitizes the body; repeated contact seems to increase the severity of the allergic reactions. About 50 percent of the population who come in contact with the resin will experience a severe form of dermatitis, and up to 10 percent will be temporarily disabled by the effects. Exposure to the resin may come from direct contact with the plant, from contact with other objects or animals that have touched the plant, or from inhaling smoke from the burning plant.

Cosmetics and Jewelry

A wide variety of cosmetics and jewelry can cause allergic reactions through skin contact. Even jewelry that is presumably pure gold can contain a certain amount of nickel that will produce a mild reaction that causes a skin discoloration, sometimes aided by chemical activity resulting from perspiration in the area of jewelry contact. Among cosmetics that may be involved in allergic reactions are certain permanent-wave lotions, eyelash dyes, face powders, permanent hair dyes, hair-spray lacquers, and skin-tanning agents. Of course, not all persons are equally sensitive to the ingredients known to be allergens, and in most cases a similar product with different ingredients can be substituted for the cosmetic causing allergic reactions. For more information on skin allergies, see “Disorders of the Skin” in Ch. 21, Skin and Hair .