Contact dermatitis is acute inflammation of the skin caused by irritants or allergens. The primary symptom is pruritus; skin changes range from erythema to blistering and ulceration, often on or near the hands but occurring on any exposed skin surface.

Irritant contact dermatitis: It accounts for 80% of all cases of contact dermatitis (CD). It is a nonspecific inflammatory reaction to substances contacting the skin

Numerous substances are involved, including chemicals (eg, acids, alkalis, solvents, metal salts), soaps (eg, abrasives, detergents), plants (eg, poinsettias, peppers), and body fluids (eg, urine, saliva)

Allergic contact dermatitis: It’s a hypersensitivity reaction

Symptoms and Signs

• Primary symptom is intense pruritus; pain is usually the result of excoriation or infection. Skin changes range from transient erythema through vesiculation to severe swelling with bullae and/or ulceration
• Any surface may be involved, but hands are most common due to handling and touching potential allergens. With airborne exposure (eg, perfume aerosols), areas not covered by clothing are predominantly involved
• The dermatitis is typically limited to the site of contact but may later spread due to scratching

Diagnosis

• Diagnosed by skin changes and exposure history
• Patch testing, standard contact allergens are applied to the upper back using adhesive-mounted patches containing minute amounts of allergen
• Skin under the patches is evaluated 48 and 96 h after application
• Common allergens used in patch test are balsam of peru, black rubber mix, resins, fragrance mix, formaldehyde

Prognosis

Resolution may take up to 3 wk. Reactivity is usually lifelong. Patients with photoallergic dermatitis can have flares for years when exposed to sun

Treatment

• Treated by avoiding the triggering agent or allergen
• Photo dermatitis should avoid exposure to sun
• Topical treatment includes cool compresses and corticosteroids
• Systemic antihistamines (eg, hydroxyzine, di phenhydramine) help pruritus.