Alternate Names : Dermatitis – contact, Allergic dermatitis, Dermatitis – allergic
Contact dermatitis is an inflammation of the skin caused by direct contact with an irritating substance.
See also: Poison ivy – oak – sumac
Overview, Causes, & Risk Factors
Contact dermatitis is an inflammation of the skin caused by direct contact with an irritating or allergy-causing substance (irritant or allergen). Reactions may vary in the same person over time. A history of any type of allergies increases the risk for this condition.
Irritant dermatitis, the most common type of contact dermatitis, involves inflammation resulting from contact with acids, alkaline materials such as soaps and detergents, solvents, or other chemicals. The reaction usually resembles a burn.
Allergic contact dermatitis, the second most common type of contact dermatitis, is caused by exposure to a substance or material to which you have become extra sensitive or allergic. The allergic reaction is often delayed, with the rash appearing 24 – 48 hours after exposure. The skin inflammation varies from mild irritation and redness to open sores, depending on the type of irritant, the body part affected, and your sensitivity.
Overtreatment dermatitis is a form of contact dermatitis that occurs when treatment for another skin disorder causes irritation.
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)
- Topical anesthetics
- Other medications
- Rubber or latex
- Fabrics and clothing
- Fragrances, perfumes
- Other chemicals and substances
Contact dermatitis may involve a reaction to a substance that you are exposed to, or use repeatedly. Although there may be no initial reaction, regular use (for example, nail polish remover, preservatives in contact lens solutions, or repeated contact with metals in earring posts and the metal backs of watches) can eventually cause cause sensitivity and reaction to the product.
Some products cause a 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, and oil from the skin of a lime. A few airborne allergens, such as ragweed or insecticide spray, can cause contact dermatitis.
Pictures & Images
Poison oak rash on the arm
Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)
Allergy to latex products may manifest itself in simple dermatitis, or in a more serious whole body reaction, anaphylaxis. The term “dermatitis” describes an inflammatory response of the skin, caused by contact with allergens or irritants such as the latex in surgical gloves or condoms. Contact with latex may produce an itchy rash, redness, blisters and scaling, or may cause the more severe anaphylaxis. Anaphylaxis is a series of symptoms including dropping blood pressure, swelling of the throat and tongue and difficulty breathing.
The term “dermatitis” describes an inflammatory response of the skin, caused by contact with allergens or irritants, exposure to sunlight, or by poor circulation, even stress. An example of contact dermatitis is the reaction of a sensitive person’s skin to poison ivy, oak or sumac. Contact with these plants, which contain a chemical called urushiol, produces an itchy rash, redness, blisters and scaling. AVOID SCRATCHING. Scratching the rash may spread the inflammation, lead to infection and even leave scars.
Dermatitis, nickel on the sole
The metal, nickel, can cause inflammation (erythema), rash, and itching. Nickel dermatitis is relatively common, and can be seen on the wrist from the stainless backs of watches, on the earlobes from nickel plated earrings, or elsewhere on the body from snaps. This person was in contact with something made of nickel or containing nickel salts.
This picture shows a skin inflammation (dermatitis) caused by contact with a material that causes an allergic reaction in this person. Contact dermatitis is a relatively common condition, and can be caused by many substances.
Dermatitis, close-up of allergic contact
This is an example of an allergic skin reaction (allergic dermatitis) caused by hair dye. The skin on the neck is red (erythematous), thickened (lichenified), scaly, and crusted.
Dermatitis, contact on the cheek
This picture shows a person with a skin inflammation (dermatitis) on the cheek caused by contact with a substance that produced an allergic reaction (allergen). Contact dermatitis causes redness, itching, and small blisters (vesicles).
Dermatitis, pustular contact
This is a close-up of a dermatitis reaction. It consists of a large, red (erythematous) lesion (plaque) with numerous small pus-filled areas (pustules).
Poison ivy on the knee
This is a typical early appearance of a poison ivy rash, located on the knee. These early lesions consist of multiple small blisters (vesicles), often in a line where the skin has brushed against the poison ivy plant.
Poison ivy on the leg
This is a typical early appearance of a poison ivy rash, located on the leg. These early lesions consist of multiple small blisters, often in a line where the skin has brushed against the poison ivy plant. The rash is caused by skin contact with the oily sap (resin) of these plants. The oily resin usually enters the skin rapidly, and is seldom transferred from person to person. The rash is not caused by the fluid from the blisters. Thus, once the person has washed the oil off the skin, the rash is usually not contagious.
Phytophotodermatitis on the hand
This person is sensitive to chemicals used in perfumes, and now develops a rash when the area is exposed to light (Phytophotodermatitis). These perfumes include Oil of Bergamot, an oil also found in some citrus fruits and wild plants. It results in streaky redness (erythema) and pigmentary changes.
Review Date : 11/1/2009
Reviewed By : Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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