Contact dermatitis is an allergic reaction affecting areas of the skin which become red, itchy and inflamed after contact with certain substances. Blisters also may form on the skin. Later these areas will ooze, thicken and crack. Contact dermatitis differs from "dishpan hands" because "dishpan hands" is an irritant reaction not an allergic reaction. The most common cause of contact dermatitis is poison ivy. Other cause's are: Other plants, cosmetics, medications, metals, and chemicals.

WHAT IS POISON IVY?
Poison ivy belongs to the plant family Anacardiasea. Other members of this family include poison oak and sumac.

WHAT HAPPENS WHEN THE SKIN COMES IN CONTACT WITH POISON IVY?
An oil resin, called urushiol (u-ru-she-ol), found in the plant's sap, causes the reaction. The response is usually not immediate and can occur 24 to 48 hours after contact has been made.

First, the skin becomes red followed by the development of bumps and blisters. Itching and swelling also may be present. After several days, the blisters break, releasing watery liquid. The blisters then begin to heal. Neither the liquid from the blister nor scratching the area will spread the rash.

WHO IS AFFECTED?
At least seven of every 10 persons could develop dermatitis if exposed to large amounts of poison ivy, oak or sumac. If contact is made through an accidental brief incident, five out of 10 persons would experience a reaction. Adults are affected more often than very young children. Heredity has not yet been shown to play a role in predicting which family members are more likely to suffer reactions than others.

TREATMENT
Clean skin and clothing with soap and water to remove the urushiol resin. This will help to prevent the development of a rash. Also wash other objects that have been in contact with the resin. This will prevent re-exposure.

Excessive scratching could cause a bacterial infection. Poison ivy allergy will not leave scars, unless such a bacterial infection is involved.

Wet, cold compresses can soothe and relieve inflammation after the blisters have broken. Calamine lotion may relieve itching and acts as a drying agent.

In severe cases, corticosteroids (cortisone) may be recommended by a physician (either topically - directly on the skin - when a small area is involved, or by mouth if a larger area is affected).

Immunotherapy (allergy injections administered over time to increase tolerance) has not been proven effective as treatment.

Avoidance is the best medicine.

WHAT METALS CAUSE CONTACT DERMATITIS?
Nickel, chrome and mercury are the most common causes of contact dermatitis.

Nickel can be found in costume jewelry, belt buckles, and wristwatches as well as zippers, snaps and hooks on clothing. Since most commercial metals like chrome contain nickel, it is likely that contact with objects that are chrome-plated also will cause skin reactions in persons sensitive to nickel.

Contact lens solutions containing mercury also can cause problems for some sensitive individuals. Persons sensitive to mercury should check the product label before using. Many contact lens solutions are available which do not contain mercury.

Once again, avoidance is the preferred treatment. Surgical stainless steel and 14 karat gold are recommended alternatives to nickel. These contain lower levels of nickel (18 karat gold contains little, if any nickel).

REACTIONS TO COSMETICS
Cosmetics, ranging from hair dyes to toe nail polish, can cause contact dermatitis or irritating reactions. Permanent hair dyes containing paraphenylenediamine are the most frequent offenders. Dyes used in clothing also can be irritating. Other products often cited include perfume, eye shadow, nail polish, lipstick and sun-screen preparations.

Hypoallergenic products are available for most cosmetic items. These products do not contain the perfume and dye which can cause allergic symptoms. These can be purchased at most stores. A list of manufacturers of hypoallergenic cosmetics is available from the American Academy of Allergy and Immunology. Those individuals with persistent symptoms, should consult their allergist.

REACTIONS TO MEDICATIONS
The most common cause of medication contact dermatitis is neomycin. This is found in antibiotic creams. Penicillin, sulfa medications and local anesthetics (novocaine, paraben) are other possible causes. Health care workers, including physicians and dentists, are at risk because of their constant exposure to these medications.

Your allergist can recommend the appropriate medication, lotion or cream to combat allergic contact dermatitis caused by adverse reactions to medications. In an effort to prevent further allergic reactions, a physician may prescribe a medication alternative when needed.