Contact Dermatitis

Background

• Contact dermatitis is an erythematous, pruritic skin reaction caused by contact with exogenous agents. Contact dermatitis can result from either an irritant or an allergen. Irritant contact dermatitis is more common than allergic contact dermatitis.
• Irritant contact dermatitis is a nonimmunologic reaction to substance or action producing direct damage to skin by chemical abrasion or physical irritation. Causes of irritant contact dermatitis include chemical agents, alcohol, creams, powders, moisture, friction, and temperature extremes.
• Most causes of occupational contact dermatitis are from irritants encountered in the workplace.
• Allergic contact dermatitis is due to a delayed immunologic response (type IV hypersensitivity) to a cutaneous or systemic exposure to an allergen to which the patient has been previously sensitized.
  • There is a latency period of 12-48 hours between exposure to allergen and clinical dermatitis in sensitized patients.
  • Poison ivy, poison sumac, and poison oak (Toxicodendron genus) are the most common causes of allergic (cell-mediated) contact dermatitis in the United States.
  • Nickel is the most common cause of metal dermatitis and a common cause of allergic contact dermatitis.

Evaluation

• The rash of contact dermatitis is typically a papular or papulovesicular pruritic eruption that may be linear or geometric corresponding to the area of contact.
• Allergic dermatitis develops over hours to days after exposure whereas irritant dermatitis typically develops over minutes to hours after exposure.
• Patients may also present with a disseminated ("id reaction") skin eruption if previously sensitized topically and then re-exposed systemically.
• Diagnosis is usually made clinically, based on history of exposure and localized rash with typical features.
• Testing is not usually needed, but use patch testing to diagnose allergic contact dermatitis and identify contact allergen (Strong recommendation).

Management

• Identify and avoid precipitating the allergen or irritant (Strong recommendation).
• When treating contact dermatitis:
  • Use topical corticosteroids for localized or mild-to-moderate contact dermatitis (Strong recommendation).
    • Apply twice daily and continue for 2 weeks.
    • Limit higher-potency steroids to use on the extremities and torso and avoid high-potency topical steroids on the face and intertriginous areas.
• Consider systemic corticosteroids for allergic contact dermatitis that is severe, widespread, or involves the face or mucous membranes.
  • The dosing of systemic steroids is not standardized.
  • Consider prednisone 0.5-1 mg/kg/day orally for 5-7 days followed by tapering dose for 5-7 days.
• Consider skin moisturizers to decrease irritation in irritant contact dermatitis.
• Consider protective skin barrier creams or moisturizers for prevention of contact dermatitis for anticipated or occupational exposures.
• For physical exposures, such as poison ivy, poison sumac, and poison oak (plants from Toxicodendron genus), wash skin and all possible affected clothing and avoid autoinoculation.