Tip 7: Allergic Contact Dermatitis
Contact dermatitis is a reaction which occurs after skin comes in contact with certain substances. Up to 80% of these reactions are irritant reactions (e.g., "dishpan hands") and 20% are allergic reactions. When the skin comes in contact with an allergic substance, the reaction is not immediate, but usually starts after one to three days and often lasts one week or longer. The skin becomes red, itchy and inflamed, frequently with blisters. The reaction is usually most severe at the site of exposure but may occur at other sites. Neither liquid from the blister nor scratching the area will spread the rash.

Who is Affected?
While genetic factors play a role, there is no way to predict who is going to develop allergic contact dermatitis. Seven of every ten people could develop dermatitis if exposed to large amounts of poison ivy, oak, or sumac. If brief contact is made, five out of ten people could experience a reaction. Adults are affected by allergic contact dermatitis more than young children or the elderly.

What Substances Commonly Cause Allergic Contact Dermatitis?
Poison ivy, which belongs to a plant family that includes poison oak and sumac, is the most common cause. Poison ivy usually grows on the ground but may grow as vines on trees. An oil resin called urushiol (u-ru-she-ol) in the plants causes the reaction. This resin can remain on tools and clothing, causing reactions with later contact.

Other plants as well as metals, cosmetics and medications can also cause a reaction. Almost 3,000 chemical agents are also known to be capable of inducing allergic contact dermatitis. A person can develop an allergy to a chemical after years of contact.

What Metals Cause Contact Dermatitis?
Nickel, chrome and mercury are the most common metals causing 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 people sensitive to nickel.

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

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

What Cosmetics Cause Allergic Reactions?
Cosmetics, ranging from hair dyes to nail polish, can cause allergic contact dermatitis. Permanent hair dyes containing paraphenylenediamine are the most frequent offenders. Dyes used in clothing also can be irritating. Other products cited for causing problems include perfume, eye shadow, nail polish, lipstick, and sunscreens.

Hypoallergenic products are available for most cosmetic items. These products are free of the perfume and dye which can cause allergic symptoms, and they can be purchased at most stores. A list of manufacturers of hypoallergenic cosmetics is available from the AAAAI. Those with persistent symptoms to cosmetics should consult their allergist.

What Kind of Medications Cause Allergic Contact Dermatitis?
The most common cause of medication contact dermatitis is neomycin, which is found in antibiotic creams. Penicillin, sulfa medications and local anesthetics (e.g., novocaine, paraben) are other possible causes. Health care workers, especially 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.

What is the Treatment for Allergic Contact Dermatitis?

  • Scrub skin with soap and water as soon after exposure as possible. 
  • Wash clothing and all objects that touched plant resins to prevent re-exposure. 
  • Take antihistamine pills, which may help lessen itching. Allergic contact dermatitis does not result in scarring unless scratching results in a secondary bacterial infection. 
  • Use wet cold compresses (2 oz. vinegar to 1 qt. water) to soothe and relieve inflammation if blisters are broken. 
  • Apply calamine lotion, which helps itching and acts as a drying agent. 
  • For severe reactions, use the most effective treatment, cortisone (corticosteroids). Non-prescription cortisone creams can be used for mild reactions, while stronger prescription creams are available for moderate reactions. Severe reactions often need to be treated with cortisone pills.
Immunotherapy via allergy shots or oral administration is in the experimental stages. Again, avoidance of substances that may cause allergic contact dermatitis is the best medicine.

Your allergist can provide you with more information on allergic contact dermatitis.

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