Contact dermatitis

Alternative names:

allergic dermatitis; dermatitis - allergic; dermatitis - contact; overtreatment dermatitis; poison ivy; poison oak; poison sumac

Definition:

A skin inflammation caused by direct contact with a substance.

Causes, incidence, and risk factors:

Contact dermatitis is a skin inflammation that results when the skin comes in direct contact with substances that can cause an allergic or inflammatory reaction. Over-treatment dermatitis is a form of contact dermatitis that occurs when inflammation results from measures used to treat another skin disorder.

The sensitivity of the skin varies from individual to individual, and may vary in the same individual from time to time. A history of any type of allergies increases the risk of contact dermatitis.

The most common type of contact dermatitis involves inflammation that results from contact with substances that may be irritants. These include acids, alkaline materials such as soaps and detergents, solvents, and other chemicals. The reaction usually resembles a thermal (heat-caused) burn.

The second type involves exposure to a material to which the person has become hypersensitive or allergic. The skin inflammation varies from mild irritation and redness, to rash, to open sores, depending on the type of allergen, the body part affected, and the sensitivity of the individual.

Common allergens associated with contact dermatitis include:

• poison ivy, poison oak, poison sumac
• other plants
• nickel or other metals
• antibiotics, especially those applied to the surface of the skin (topical antibiotics)
• rubber and latex
• cosmetics
• topical anesthetics or other medications that are applied to the surface of the skin
• detergents
• solvents
• adhesives
• fragrance, perfumes
• other chemicals and substances

Contact dermatitis may involve reaction to a substance that the person is exposed to or uses repeatedly. Although there may be no initial reaction, repeated use (for example, of nail polish remover, preservatives in contact lens solutions, or repeated contact with metals in earring posts and the metal backs of watches) can cause eventual sensitization and reaction to the product.

Some products cause reaction only when they contact the skin and are exposed to sunlight (photosensitivity). These include shaving lotions, sunscreens, sulfa ointments, some perfumes, coal tar products, oil from the skin of a lime, and others. A few airborne allergens, such as ragweed or insecticide spray, can cause contact dermatitis.

Contact dermatitis may result from occupational (work related) or recreational exposure to substances. With widespread precautions against HIV virus and other blood-borne pathogens, contact dermatitis caused by exposure to latex (found in surgical gloves, condoms, and similar products) is becoming more common.