Contact Dermatitis Overview
Contact dermatitis is an eczema-like skin reaction that is produced by exposure to an irritating substance such as detergents, soaps, certain plants, and solvents. It can also be caused by an acquired hypersensitivity to an allergen, which is a substance that causes an allergic reaction. The first exposure to a particular allergen does not trigger a reaction or irritation, but causes the person to develop sensitivity. Subsequent exposure then produces an itchy rash.
Causes of Contact Dermatitis
Irritant contact dermatitis is caused by substances that are harsh to the skin. Substances that commonly cause the condition include
- detergents and soaps,
- bleaches, solvents, acids and alkalis,
- bubble baths, and
- urine and feces.
Infants have thin, sensitive skin that is easily irritated and reddened, and people with disorders that alter the skin's protective barrier are more susceptible to irritation by harsh substances. Other skin rashes and moist, chafed areas make one particularly susceptible as well.
Allergic contact dermatitis develops after sensitivity and further exposure to an allergenic substance. Examples of this include reactions to contact with
- poison oak or poison ivy;
- nickel plating on earrings, watches, and belt buckles; and
- rubber or glues in shoes.
Some allergens, such as sunscreens and fragrances, become sensitizing only when exposed to the sun.
According to our sister publication REMEDY's Healthy Living (Summer 2015), use care if you see shampoo, soap, cosmetics, and other personal care products carrying claims such as "hypoallergenic" or "dermatologist tested." Keep in mind that these are just marketing termsthe U.S. Food and Drug Administration (FDA) does not require these claims to be substantiated.
A study in The Journal of Allergy and Clinical Immunology analyzed 187 products marketed as hypoallergenic and found that 89 percent of them contained at least one chemical known to cause allergic skin reactions in sensitive people; some had five or more allergens. Many of the allergens are preservatives (such as methylisothiazolinone) or fragrances.
Updated by Remedy Health Media