Allergic contact dermatitis is inflamed skin (dermatitis) that occurs when allergic-causing substances (allergens) touch the skin. In people who are sensitive to them, the allergens cause a skin reaction. Itching, redness, scaling, a rash, and, if severe, blisters may occur.
Another name for this skin problem is allergic contact rash. The best way to prevent this type of rash is to find what you are allergic to and avoid contact with it.
Common allergens include metals, rubber, dyes, antibiotics, cosmetics, preservatives, and fragrances.
Metals are in many products, including jewelry, metal buttons, clothing fasteners, dental filings, and cell phones.
Nickel is the most common metal to cause skin allergies. Nickel is in metal products, including gold jewelry. It is often in metal alloys. Many chrome-plated objects contain enough nickel to cause a reaction in sensitive people. For instance, earrings containing nickel often can cause a rash on the earlobe. People who are allergic to nickel should wear nickel-free jewelry.
Chromates contain chromium. Allergic contact rashes are common from chromates in cement, metal, leather, some matches, paints, epoxy-based sealants, and anti-rust products. Chromates are also used to tan leather for shoes and can cause “shoe dermatitis” (a rash in the shoe area). Vegetable-tanned footwear is an option.
Natural latex and synthetic rubber products often cause allergic contact rashes. Chemical additives in rubber are most often the cause of the allergy. Despite being a well-known allergen, a synthetic rubber product called polychloroprene is in wide use. Besides the typical symptoms of an allergic contact rash, this product can cause bleeding onto the skin.
Latex rubber gloves are a frequent source of allergic contact rash on the hands. People are more likely to get this type of allergy if they have inherited allergies, food allergies, or hand dermatitis (eczema). People with a latex allergy should wear vinyl gloves. They should wear shoes with soles that are not rubber and underwear with elastic bands that do not contain latex.
Some people are sensitive to hair dyes and other products containing phenylenediamine (PPD). This chemical is in “permanent” (long-lasting) hair dyes that are mixed with another chemical, such as peroxide, before use. While PPD is the most common allergen linked in hair dyes, other compounds can cause allergies.
PPD may be mixed with henna for temporary tattoos. People who are allergic to PPD will react to these tattoos. In bad reactions, scars may result.
Antibiotics that are topical (applied to the skin) have frequent use in wound treatment. Some topical antibiotics have cause allergic contact rashes. These include neomycin, bacitracin, gentamicin, kanamycin, and polymyxin. The antibiotic that most often causes allergic contact rash is neomycin. Neomycin is in both prescription and non-prescription antibiotic creams, ointments, lotions, ear drops, and eye drops. Some topical medicines mix neomycin with corticosteroids and other antibiotics, such as triple antibiotic first aid creams, and should be avoided.
Perfumes, lotions and cosmetics are common causes of allergic contact rashes. Some people are sensitive to the fragrance chemicals. People with fragrance allergy can use fragrance-free products. “Unscented” products, though, may still have a “masking” fragrance to cover up the smell of the chemicals. Other people are sensitive to one or more preservatives that prevent skin care and personal care products from spoiling.
Often, you will need allergy skin tests called patch tests. Patch tests are a safe, easy way to detect contact allergies. Patch tests differ from intradermal (injection), prick, or scratch skin tests, which put the allergen into the skin. In patch tests, the dermatologist puts small amounts of your suspected allergens on strips of tape and applies these strips on the skin. After two days, the doctor removes the strips. A red spot at the site of the patch shows an allergy.
Mild rashes most often respond to steroid creams and/or oral (taken by mouth) antihistamines. For very aggravated rashes, your dermatologist may give you oral corticosteroids or injections (shots). You may need other anti-inflammatory medicines or immunologic therapies. If your skin becomes infected, you may get antibiotics.
People who get allergic contact rashes should avoid the allergen that causes the reaction. Your dermatologist will help you find out the items you need to avoid. Also, the dermatologist can suggest products that do not contain the allergen and will not cause reactions