By David L. Schneider M.D., Allergist & Immunologist
Contact dermatitis is a type of red, itchy rash or irritation that occurs when certain substances come in contact with the skin. According to the Asthma and Allergy Foundation of America, about 80 percent of skin reactions are caused by direct contact with an irritating, harsh or dangerous chemical. The other 20 percent are due to allergic contact.
Irritant dermatitis is caused by the interactions of acidic or alkaline materials found in soaps and detergents, fabric softeners and solvents. Other compounds like cement, hair dyes, pesticides or herbicides, rubber gloves and even shampoos and some mouthwashes can contain irritants to trigger a rash.
Allergic contact dermatitis (also called allergic contact eczema) reflects a specific sensitivity or allergy to a particular substance like poison ivy, poison oak, poison sumac, makeup, gold jewelry, nickel or latex. Often, allergic contact dermatitis may take years to develop and repeated exposure to a particular substance may trigger an allergic reaction over time.
Of note, substances found in some products only cause an adverse reaction when exposed to sunlight. Such products can include sunscreens, shaving lotions, cosmetics, and perfumes. Topical antibiotics such as Neosporin and Bacitracin and orally administered drugs such as penicillin, sulfa drugs, barbiturates, anticonvulsants and iodine (found in many X-ray contrast dyes) can cause adverse reactions. Checking with your allergist or pharmacist to find out if any medicines you take could cause a photo-sensitive rash is always a good idea.
Symptoms of contact dermatitis vary depending on the cause and whether the dermatitis is due to an allergic reaction or an irritant. The same person may experience different symptoms over time. Typical symptoms of contact dermatitis can include:
Red and blistering rash
Mild to severe itching
Bumps or blisters that may ooze fluid
Cracking or peeling of the skin
To diagnose the problem, the allergist will review your medical history, confirm the use of any medications or creams, inquire about your activities and the onset of symptoms including how long after exposure the rash occurred.
Your allergist will then do a physical examination and may perform patch testing to identify the culprit.
If you feel you are at risk for dermatitis, consider these preventive steps:
Wear loose-fitting, natural-fiber clothing; untreated cotton is ideal.
Avoid plated jewelry, especially in your ears, to prevent nickel-related rashes. Surgical steel or 18-karat gold earring posts are safer choices.
Don't wear a watchband that presses against your skin for long periods; it may contain nickel. The friction and sweat buildup under the watch touching your skin may spread the rash.
Choose hypo-allergenic soaps and cosmetics (e.g. Almay and Clinique are good examples)
Use cortisone cream and lanolin-free moisturizers
Most importantly, the knowledge gained from patch testing can help avoid exposure to suspected triggers.
Distinguishing allergic contact dermatitis from irritant contact dermatitis and other forms of eczematous dermatitis can be challenging. If contact dermatitis symptoms are making you miserable, make an appointment with a Board Certified allergist/immunologist for evaluation and treatment. Allergists have at least two additional years of specialized training in the diagnosis and treatment of allergic rashes, allergic rhinitis, asthma, immune deficiencies and other immunologic diseases.