Contact Dermatitis and Related Disorders Part 2

Treatment of irritant and allergic contact dermatitis

Most cases of contact dermatitis can be effectively treated and controlled once the offending irritant or allergen is identified and eliminated. Identifying hidden sources of allergens is important, and patients who have positive patch-test results are given exposure lists identifying various names of allergens, cross-reacting substances, lists of potential products and processes containing the allergen, and nonsensitizing substitutes. Standard texts should be consulted for detailed information12,17; the Internet is also a source of information on treatment of contact dermatitis [see Sidebar Internet Resources on Contact Dermatitis]. Examples of allergen alternatives include topical ery-thromycin or mupirocin ointments as substitutes for neomycin.25 Neomycin may cross-react with gentamicin and tobramycin. Bacitracin should generally be avoided for neomycin-sensitive patients because of coreactivity.

Reasons for persistence of ACD include unidentified sources of allergens or irritants at home or at work, exposure to cross-reacting allergens, presence of underlying endogenous (e.g., atopic) eczema, and adverse reactions to therapy [see Topical-Medication Allergy, below].

Reduction of Trigger Factors

In the case of hand dermatitis, practical management must include protective measures, topical corticosteroids, and lubrication. The use of vinyl gloves with cotton liners to avoid the accumulation of moisture that often occurs during activities involving exposure to household or other irritants and foods (e.g., peeling or chopping fruits or vegetables) may be helpful. However, it is important to verify that gloves are safe to use in the workplace around machinery before recommending them. Protective devices themselves may introduce new allergic or irritant hazards in the form of rubber in gloves and solvents in waterless cleansers. Barrier creams are generally the last resort and are probably best for workers who do not have dermatitis.26 Hand alcohol may be a superior disinfectant to soap and water in occupations that require extensive wet-work exposure.27 A barrier agent containing quaternium-18 bentonite has been shown to be effective with exposure to a specific allergen, such as poison ivy.28 Principles of treatment of atopic dermatitis may also be applied to treatment of contact dermatitis [see 2:IV Eczematous Disorders, Atopic Dermatitis, and Ichthyoses].

Topical Therapy

Treatment of contact dermatitis depends on the severity of the dermatitis. When acute serous oozing is present, cool, wet compresses should be applied for 15 minutes two or three times a day. Isotonic saline or Domeboro powder dissolved in tap water to make a 1:40 dilution (aluminum acetate) may be used. A soft cloth, such as Kerlex gauze or a towel, is immersed in the solution. The cloth is wrung slightly and applied to the affected area of the skin. The solution should not be poured directly on the dressing. Lukewarm to cool water baths or sitz baths are an-tipruritic and anti-inflammatory; they also aid in cleansing and removing crusts and medications. Oatmeal in the form of Aveeno Oilated Bath Treatment (colloidal powdered oatmeal with oils) may be added to the bath for its antipruritic and drying effects.

In acute vesicular dermatitis such as that caused by poison ivy, treatment with compresses and baths should be followed by the application of a topical corticosteroid spray (either triamcin-olone acetonide [Kenalog aerosol] or betamethasone dipropi-onate [Diprosone aerosol]). A spray of 2 or 3 seconds’ duration on each affected area supplies sufficient coverage, providing the container is held 6 in. from the skin. In cases in which the dermatitis is extensive or less vesicular, one of the many topical cor-ticosteroid creams may be used. Corticosteroid creams range in potency from extremely potent (e.g., clobetasol propionate [Te-movate]), to potent (e.g., betamethasone dipropionate [Dipro-sone topical cream]), to midstrength formulations. In addition, a lotion of camphor, menthol, and hydrocortisone (Sarnol-HC) is soothing, drying, and antipruritic. Pramoxine, a topical anesthetic in a lotion base (Prax), may also relieve pruritus.

In the subacute and chronic stages of contact dermatitis, an emollient lotion (Eucerin) or ointment (Aquaphor) may be applied to moist skin after bathing for lubrication. Oil-in-water emulsions that contain perfluoropolyethers have been shown to significantly inhibit ICD caused by a wide variety of hydrophilic and lipophilic irritants.29 A potent or midstrength topical gluco-corticosteroid cream or ointment is often used in the treatment of subacute and chronic contact dermatitis. Hydrocortisone 1% is only occasionally effective. Fluorinated corticosteroids should be used with discretion; frequent and prolonged use of these agents in skin-fold areas may cause atrophy, telangiec-tasia, or striae, and their use on the face may cause steroid rosacea. For patients with chronic dermatitis, crude coal tar preparations may be used to control eczema. Topical PUVA treatment may be effective for contact dermatitis of the palms and soles.30

Table 5 Patch-Test Results in North America from 2001 through 2002¹¹

Table 5

*Allergens in petrolatum unless noted aqueous (aq).

^Definite, probable, or possible reactions detected in percentage testing population.

TT—T.R.U.E. (thin-layer rapid-use epicutaneous) test

Systemic Therapy

Intense itching may be relieved with sedating antihistamines such as diphenhydramine hydrochloride (Benadryl), hydroxy-zine hydrochloride (Atarax), and doxepin hydrochloride (Sine-quan), administered at night. Most cases of ICD and ACD are effectively managed without the use of systemic corticosteroids. However, short courses of systemic corticosteroids are indicated for patients with severe vesiculobullous eruptions of the hands and feet or the face [see Figure 9] or with severe disseminated ACD, such as poison ivy. Strategies to reduce the side effects of corticosteroid use are especially important in patients who have diabetes, hypertension, glaucoma, latent or active tuberculosis (as indicated by a positive skin-test reaction to purified protein derivative), and diseases that could be affected by steroid therapy. Attempts at desensitization have generally been unsuccessful.8 Secondary infection sometimes arises as a complication of ICD and ACD; in such cases, systemic antibiotics may be indicated.29