What is the first line of treatment for contact vs allergic dermatitis?

First-Line Treatment for Contact Dermatitis

For both irritant and allergic contact dermatitis, the first-line treatment is identification and complete avoidance of the causative agent, combined with mid-to-high potency topical corticosteroids for inflammation and aggressive emollient therapy to restore the skin barrier. 1

Distinguishing Between Irritant and Allergic Contact Dermatitis

• Clinical features alone are unreliable in distinguishing between irritant and allergic contact dermatitis, particularly on hands and face, making patch testing essential when the diagnosis remains uncertain. 2, 1
• Irritant contact dermatitis results from direct chemical damage without immune involvement, typically from repetitive exposure to soaps, detergents, solvents, or single overwhelming exposures to caustic agents. 2, 3
• Allergic contact dermatitis involves delayed-type hypersensitivity (Type IV) to specific allergens like nickel, fragrances, preservatives, or rubber chemicals, requiring prior sensitization. 2
• Allergic contact dermatitis carries a worse prognosis than irritant dermatitis unless the specific allergen is identified through patch testing and completely avoided. 3

First-Line Treatment Protocol

Immediate Management for Both Types

• Apply mid-to-high potency topical corticosteroids such as triamcinolone 0.1% or betamethasone valerate 0.1% to affected areas 3-4 times daily for localized disease. 1, 4, 5
• For severe or recalcitrant cases, escalate to very high potency topical corticosteroids like clobetasol propionate 0.05% for up to 2 weeks, which achieves clear or almost clear skin in 67.2% of patients with severe dermatitis. 1, 5
• Replace all soaps and detergents with emollients immediately, as these are common irritants that perpetuate dermatitis. 1
• Apply moisturizers liberally using the "soak and smear" technique: soak affected areas in plain water for 20 minutes, then immediately apply two fingertip units of moisturizer to damp skin. 1
• Use moisturizers packaged in tubes rather than jars to prevent contamination. 1

Allergen Identification and Avoidance

• Refer for patch testing with at least an extended standard series of allergens if dermatitis persists beyond 2-3 weeks, if the pattern is atypical, or if the causative agent remains unknown. 2, 1
• Patch testing has 70-80% sensitivity and specificity for confirming allergic contact dermatitis and identifying specific allergens. 3
• Take a detailed history including initial symptom location, spread pattern, relationship to specific products or activities, and occupational/recreational exposures. 1
• Consider workplace visits if occupational exposure is suspected to identify hidden allergens and assess procedures causing accidental exposure. 1

Protective Measures

• Use appropriate protective gloves based on suspected exposures: rubber or PVC gloves with cotton liners for household tasks, neoprene or nitrile for latex allergy. 1
• Remove gloves regularly to prevent sweat accumulation, which aggravates dermatitis. 1
• Apply moisturizer before wearing gloves to enhance barrier protection. 1
• Do not over-rely on barrier creams alone, as they have questionable value and may create false security. 1

Systemic Therapy for Extensive Disease

• If allergic contact dermatitis involves greater than 20% body surface area, oral prednisone is required and provides relief within 12-24 hours. 6, 5
• For severe rhus (poison ivy) dermatitis, taper oral prednisone over 2-3 weeks to prevent rebound dermatitis from rapid discontinuation. 5
• Avoid oral corticosteroids during patch testing; if unavoidable, keep prednisolone ≤10 mg daily to prevent false-negative results. 1

Second-Line Therapies for Refractory Cases

• Consider topical tacrolimus 0.1% where topical steroids are unsuitable, ineffective, or when chronic facial dermatitis raises concerns about steroid-induced skin damage. 2, 1
• PUVA phototherapy is an established second-line treatment for chronic hand eczema resistant to topical steroids. 2, 1
• For severe chronic hand eczema, alitretinoin is recommended by the British Association of Dermatologists. 2
• Systemic immunosuppressants like azathioprine or ciclosporin may be considered for steroid-resistant chronic cases. 1

Critical Pitfalls to Avoid

• Never wash hands with dish detergent or other known irritants, use very hot or very cold water, or apply disinfectant wipes to clean hands. 1
• Avoid prolonged occlusion without underlying moisturizer application, as this worsens barrier dysfunction. 1
• Exercise extreme caution with topical corticosteroids on facial skin—prolonged use causes skin thinning, telangiectasia, perioral dermatitis, and red face syndrome due to increased percutaneous absorption. 1
• Do not apply potent topical steroids to the back within 2 days of patch testing, as this causes false negatives. 1
• Avoid products containing topical antibiotics without indication, as these are common sensitizers, particularly in children. 1, 3
• Be aware that a small subset of patients may develop allergic contact dermatitis to topical corticosteroids themselves, requiring patch testing to corticosteroid allergens. 2, 7

Prognosis Considerations

• Only 25% of patients with persistent contact dermatitis achieve complete healing over 10 years, with 50% having intermittent symptoms and 25% having permanent symptoms despite treatment. 1
• Early identification and complete avoidance of allergens offers the best chance for resolution. 1
• Changing occupation does not improve prognosis in 40% of cases of occupational contact dermatitis. 1