Introduction

For some people, objects as common as rubber-soled shoes, jewelry, or cleaning products can cause contact dermatitis, a type of skin reaction.  Contact dermatitis appears as an itchy red rash on the skin.  It develops when the skin touches a substance that causes an allergic reaction or has direct contact with a harmful material.  In many cases, contact dermatitis is relieved with good washing and over-the-counter medications.  You should contact your doctor if your symptoms are severe or do not improve.  Skin testing by an allergist can identify substances that you are allergic to and should avoid helping prevent future outbreaks.

Anatomy

Your immune system usually fights germs to keep you healthy.  If you have allergies, your immune system overreacts to ordinary substances that normally are not harmful.  The substances that trigger an allergic reaction are called allergens.

When you are exposed to an allergen, your white blood cells produce antibodies.  The antibodies trigger the release of histamine and other chemicals in your blood called mediators.  The mediators can cause a rash to appear on the skin.

Causes

Allergic contact dermatitis is a type of contact dermatitis that is caused by direct contact with an allergen, such as poison ivy, metals in jewelry, makeup, skin medications, or latex.  Irritant contact dermatitis is the second type of contact dermatitis that is caused by direct contact with substances that damage the skin, such as chemicals, cleaning products, and detergents.

Symptoms

Contact dermatitis causes a red rash that itches or burns.  A widespread rash appears immediately with irritant contact dermatitis.  A localized rash may take a couple of days to appear with allergic contact dermatitis.  The rash may form blisters or hives.

Diagnosis

Your doctor can diagnose contact dermatitis by reviewing your medical history and examining your rash.  You should tell your doctor what you have been in contact with.  If you experience frequent or significant rashes, skin testing by an allergist can identify the specific allergens that cause your reactions.

Treatment

You should wash the affected skin thoroughly with soap and water.  Over-the-counter soaps are available specifically to remove poison oak, poison ivy, and poison sumac oils.  Over-the-counter oral antihistamines, antihistamine lotions, or hydrocortisone creams can help relieve itching and inflammation.  In severe cases, prescription-strength antihistamines and corticosteroid medication may be received as pills or through injection. 

Prevention

You should avoid the items or substances that cause your contact dermatitis.  Wear long-sleeved shirts, gloves, and pants when you are in weeded areas.  Wash exposed clothes, towels, bath linens, and pets in the special soaps that remove poison oak, poison ivy, and poison sumac oils.  Follow the safety instructions on the labels of harmful chemicals.  Wash your skin immediately with soap and cool water if an allergen or harmful substance contacts your skin.

Am I at Risk

You are at risk for contact dermatitis if:
• You are in direct contact with allergens.
• You are in direct contact with harmful chemicals or substances.
• You have another skin condition, such as eczema.
• You have had contact dermatitis rashes in the past.

Complications

You should avoid scratching to help prevent the spreading of the inflammation.  Open rashes are at risk for bacterial infections, such as staph infections.  Poison ivy should never be burned.  The smoke can cause infections in the eyes and lungs.  If you experience frequent or severe contact dermatitis, you should seek evaluation from an allergist.