General Description

Inflammation of the skin that follows contact with an external agent may be produced in two different ways. In some instances, referred to as irritant dermatitis, the substance acts as a simple irritant causing direct damage to the skin. In the case of a contact allergy, a substance invokes an allergic reaction. Contact dermatitis results in nearly six million visits to physicians each year in the United States.

Causes

Irritant Dermatitis

Treatment of irritant dermatitis involves protection and rest of the involved area. Strict avoidance of excess heat, moisture, harsh soaps, and detergents is essential. Those affected should avoid unnecessary wetting of the hands. Because it is not unusual for irritant dermatitis to begin in the moist environment under rings that traps soap, chemicals, and dirt, all such jewelry should be removed before wet work. Specially formulated barrier-protectant emollients help to insulate the skin from environmental damage. Examples include Kerodex, Proteque, Tetrix and TheraSeal.

When washing the hands, use lukewarm water and, if possible, a mild cleanser such as Aquanil,CeraVe, Cetaphil, or baby soap. Cleansers should be used sparingly and the hands thoroughly rinsed. Dry carefully with a clean towel, remembering to dry between the fingers. Plastic gloves or lined rubber gloves should be worn when washing dishes and clothes, when peeling or squeezing citrus fruits, and when in contact with harsh chemicals. Gloves should not be worn for more than twenty minutes at one time. If water happens to enter the glove, it must be removed immediately.

Affected hands should be lubricated with a skin cream or lotion several times during the day. Prescription preparations containing cortisone may be required in more severe cases.

Cosmetic Allergy

In some cases, a person may use a skin care product for years without any problem and then suddenly become allergic to one of its ingredients. For this reason, one must always suspect an allergic reaction whenever inflammation of the skin develops in an area of topical application.

Should an allergic response be suspected, topical products are best discontinued. If the reaction subsides, it can be assumed that one of the eliminated products contains the offending agent. If necessary, to ascertain the offending product, possible culprits may be applied daily to the same small area of the arm, which should then be checked for signs of an allergic response. Alternatively, a dermatologist can test for an allergic reaction to specific ingredients by a simple process called patch testing, which consists of applying commonly found substances to the skin under an occlusive dressing kept in place for forty-eight hours, and then analyzed for redness and swelling. The most common ingredients that lead to allergic reactions in cosmetics are fragrance and preservatives.

The term hypoallergenic has been applied to a large number of cosmetics. Since nearly all cosmetics are carefully screened for allergic potential before marketing, most are indeed hypoallergenic and will not induce reactions in the majority of users.

Cosmetic Allergy: Common Culprits

Fragrances: Thousands of different fragrances are in use today in products such as perfumes, shampoos, soaps, deodorants, and moisturizers. Even products labeled “unscented” may contain masking fragrances. An allergic reaction typically occurs on the face and hands. When a spray such as a perfume is involved, redness and itching of the neck is classic as well.

Preservatives: Preservatives are used to extend the life of products and represent the second most common cause of contact dermatitis to cosmetics. Ingredients linked to preservative allergic reactions include quaternium-15, parabens, and thimerosal.

Hair dyes: Ingredient labels found on hair dyes request that users regularly test for allergic reaction prior to use. The most common allergen is phenylenediamine (PPD), the key ingredient in permanent hair dye. Allergic reactions may occur on the forehead and neck prior to affecting the scalp. PPD is also a commonly found ingredient in black henna temporary tattoos.

Nail products: Allergic reactions to nail polish and acrylic nails may present as redness and swelling about the nail. Touching the face and eyelids with the fingertips can induce a reaction at these sites as well. Causative chemicals include formaldehyde-based resins and acrylates. 

Jewelry Allergy

Allergy to jewelry is quite common. A recent study has demonstrated that nearly one out of every ten females is sensitive to nickel. People with nickel allergy develop redness, scaling, and itching wherever this metal comes into contact with the body. Common sites include the earlobes (from earrings), upper chest and back (from bra straps), waistline (from belt buckles), and wrists (from watchbands or bracelets). Nickel allergy is on the increase in part due to the popularity of body piercings and the ubiquitous presence of this metal. In fact, nickel was designated “Allergen of the Year” in 2008 by the North American Contact Dermatitis Group.

Once a person becomes allergic to nickel, this sensitivity persists indefinitely. Thus, affected persons should avoid all prolonged contact with this metal. A chemical solution (dimethylglyoximine) may be applied to any piece of metal to assay for the presence of nickel. Many dermatology offices are equipped to test for this substance. Sterling silver, gold, and platinum earrings may be worn, but chances are great that costume and gold-plated jewelry contain nickel.

 Nickel allergy frequently occurs following ear and body piercing. For this reason, body parts should be pierced with stainless steel instruments, and only stainless steel ornaments should be worn for at least the first month.

Plant Allergy

The most common plant allergy is due to poison ivy. Other offenders include poison oak, sumac, and the mango plant. All contain the same irritating chemicals, and all can produce itchy eruptions.

Plant dermatitis follows exposure of a body part to the leaves of an offending plant or to materials that have been in close contact with the plant, such as animal fur, tools, or clothing. Between twenty-four hours and one week following exposure, an itchy rash appears at the site of contact. Tiny fluid-filled blisters arise in patches and streaks. If the allergic material from the plant remains under the nails, poison ivy may be spread to unexposed areas by the fingers.

The best way to prevent any allergic dermatitis is through avoidance. Persons susceptible to poison plant allergy (this includes about 60 percent of the population) should be familiar with these plants and remain vigilant when gardening, camping, etc. When walking in wooded areas, wear pants, long-sleeved shirts, and socks. Poison ivy plants may be physically removed (wear gloves!) or chemically destroyed. Exposed skin should be thoroughly washed within fifteen minutes to avoid penetration of the noxious plant chemical. Specific barrier creams (such as IvyBlock) may afford adequate protection when applied prior to exposure.

Mild cases of allergic dermatitis may be treated with drying compounds such as calamine lotion and oatmeal baths. Severe cases of poison ivy, especially those affecting the eyelids, are best managed by a physician. Oral desensitization to prevent the allergic reaction of poison ivy is currently being tested but cannot be recommended at the present time.

Latex Allergy

The most common reactions to latex are either irritant or allergic dermatitis, generally localized to sites of exposure, mainly the hands. In some individuals, latex allergy has been linked to constriction of the airways (anaphylaxis) and to death from airway closure.

Remedies