If you develop redness, swelling, cracking, blisters, or itching on your skin when you come in contact with certain substances, you may have “contact dermatitis” (CD) or a skin allergy. CD is caused either by an allergy or a sensitivity/irritation to common substances. 80% of skin reactions are caused by direct contact with an irritating product such as household cleaners, detergents and soaps among others that can cause irritant CD in all exposed individuals, especially with prolonged use.
What is Allergic Contact Dermatitis?
The skin is one of the first places where symptoms of allergy can appear. For people with a skin allergy or allergic CD, the immune system overreacts to substances in direct contact with the skin, which are referred to as “allergens.”
Is Eczema the Same as Allergic Contact Dermatitis?
No. Eczema, also known as atopic dermatitis (AD), is a skin disorder that commonly affects children but can also occur in adults. Although not all eczema cases are related to allergies, eczema tends to run in families, and people with eczema usually have a family history of one or more allergic conditions such as asthma, hay fever, hives or seasonal allergies. People that suffer from eczema have cracked skin and a higher incidence of irritant and allergic reactions after coming in contact with various products due to increased penetration through the diseased skin.
What Causes Allergic Contact Dermatitis?
Exposure to chemicals found in many different products may cause a skin allergy including detergents and cleaning products; sunscreens; hair, dental and baking products; plastic and glues; adhesive and surgical tape; and photography products. Other offending agents include:
Poison ivy (number one allergen), poison oak, poison sumac, other plants
Metals, such as nickel (very common allergen in metal buttons, cheap jewelry, watches, zippers, kitchen utensils, etc)
Fragrances, perfumes (soaps, deodorants,
body creams, cosmetics, scented toilet paper, etc)
Dyes for hair, clothing, leather, furs
Preservatives (shampoos, cosmetic products,topical medications, etc)
Nail care products (nail polish remover, hardeners, etc)
Rubber compounds (waistbands, gloves, bras, condoms, etc)
Medications, including topical antibiotics, steroid creams and topical anesthetics
An allergic CD occurs gradually over time after repeated use of a substance. Once that threshold is crossed, the individual develops a specific sensitivity so even brief contact with that allergen may cause allergic contact dermatitis to reappear within 24-48 hours. Some products cause a reaction only when the person is exposed to sunlight after the contact with the substance (photo-contact dermatitis). These commonly include sunscreens, shaving lotions, topical antibiotics, perfumes, coal tar, and lime juice. A few airborne allergens such as ragweed or insecticide spray can also cause allergic contact dermatitis on the exposed areas. Often the offending substance(s) can be “obscure” components of a product, so be sure to carefully read labels. Even products marked as “hypoallergenic” can still contain fragrances and “unscented” products may contain small amounts of fragrance used to mask unpleasant odors.
What are the Symptoms of Contact Dermatitis?
Symptoms of CD range from mild to severe and include red, itchy, swollen, and warm skin, sometimes accompanied by oozing or blistering. Peeling of skin may follow. Symptoms usually appear on the areas that were in contact with the offending substance(s).
How is Allergic Contact Dermatitis Diagnosed?
The gold standard for diagnosing CD is “skin patch-testing,” which identifies the substances suspected of causing the allergy. Patch testing requires three office visits. A complete physical and detailed history helps the specialist tailor specific patch tests for each patient. On the first visit, small patches of potential allergens are applied to upper back skin. These patches are removed 48 hours later to evaluate for a reaction. A third visit 1-2 days later assesses late reactions. Patients should also bring along suspected materials for testing in addition to the standardized patch tests.
Topical corticosteroids or in severe cases oral steroids are needed to alleviate the redness and itching.
CD usually clears without complications within several weeks, but may recur if the offending substance cannot be identified or removed. A change of occupation or occupational habits may be necessary if the disorder is caused by occupational exposure, which can affect hairdressers, dentists, florists, and many others.
Avoid contact with suspect materials. If contact is unavoidable, use protective gloves or other barriers and wash skin surfaces thoroughly with soap and water after contact.
Who will benefit from patch testing? Patients with: (1) long-standing, recurring skin rash, with an unknown cause, (2) atopic dermatitis/eczema, (3) sensitive skin, that cannot tolerate skin contact with cosmetic products, (4) exacerbation in their rashes after use of topical medicaments, (5) hand dermatitis, (6) a suspected dermatitis due to occupational exposure, and (7) a rash in a sun-distributed area. If you suspect a skin allergy, ask your doctor to refer you for extensive patch testing to a specialized contact dermatitis clinic. Patch tests should be done only by dermatologists who specialize in these procedures. Most health insurers cover extensive patch tests which might benefit many patients with long-standing skin rashes or eczema.
Emma Guttman, MD, PhD
Assistant Professor of Dermatology & Immunology
Director of Occupational and Contact Dermatitis
Director of the Laboratory of Inflammatory Skin Diseases, Department of Dermatology
To schedule an appointment call (212) 241-9728 or visit the on-line registration at www.MountSinaiDermatology.com