EVIDENCE-BASED ANSWER
Scant evidence exists for the best duration of steroid therapy for contact dermatitis due to plants (rhus). Review articles recommend 10 to 21 days of treatment with topical or oral corticosteroids for moderate to severe contact dermatitis due to plants (strength of recommendation [SOR]: C, based on review articles). The primary reason given for the duration of 2 to 3 weeks is to prevent rebound dermatitis.
CLINICAL COMMENTARY
Prescribe oral steroids for severe cases
Brian Crownover, MD, FAAFP, Lt Col, USAF, MC
US Air Force, Eglin Family Medicine Residency, Eglin Air Force Base, Eglin, Fla
Evidence for the best treatment of rhus dermatitis is negligible. Most recommendations stem from review articles and expert opinion. Rhus dermatitis is one example of a disorder for which we must fall back on our logic and personal experience. Since the painful itchy blisters and erythema from the oleoresin may take up to 1 week to appear, and because the rash may persist for more than 2 weeks, it makes sense to prescribe oral steroids in severe cases for longer than the usual 5- to 7-day burst. Habif, a popular dermatology text, suggests gradually tapering steroids from 60 to 10 mg over a 14-day course.1 In the absence of any randomized controlled trials (and remembering my patient who bounced back after I only gave 1 week of steroids), I will continue to prescribe 14 days of oral steroids.
Evidence summary
No published studies compare varying durations of treatment with steroids for contact dermatitis due to plants, including rhus. Many review articles refer to rebound dermatitis when using courses of oral steroids (such as Medrol dosepaks) for fewer than 14 days. One case report noted failure of a tapering dose over 5 days of oral methylprednisolone for treatment of poison ivy contact dermatitis.2
Most review articles recommend systemic steroids for severe poison ivy contact dermatitis, but these articles do not define “severe,” describe the taper, or give a definite length of treatment.3-5 One review recommends a tapering dose of oral prednisone to prevent rebound recurrence if the rash affects >25% of the body surface area, has severe blistering or itching, or significantly involves the face, hands, or genital area. That review suggests starting with oral prednisone 60 mg/d for 4 days, followed by a 10-day taper (50 mg/d for 2 days, 40 mg/d for 2 days, 30 mg/d for 2 days, 20 mg/d for 2 days, then 10 mg/d for 2 days).3
Another review recommends using systemic steroids for severe cases, defined as involvement of greater than 20% of total body surface area, bullae formation, or extensive facial involvement. That review recommends a starting dose of 1 mg/kg/d, or 40 to 60 mg/d in adults, followed by a 2- to 3-week taper of oral prednisone.4 A third review recommends using prednisone for children with allergic contact dermatitis involving more than 10% of the total body surface area.5
Recommendations from others
Guidelines for treatment of contact dermatitis published by the American Academy of Dermatology recommend topical treatment alone for mild cases of contact dermatitis, defined as “limited site of involvement, acute contact dermatitis when the offending agent has been removed, or chronic contact dermatitis with limited symptoms.” The guideline states that systemic treatment may be indicated to control itching or edema, or for moderate to severe cases. The systemic treatments listed include oral or intramuscular corticosteroids, but no discussion of duration is mentioned.6
UpToDate discusses avoidance of the offending substance for 2 to 4 weeks, use of topical corticosteroids of medium to strong potency for a limited time (without defining the duration), and use of systemic corticosteroids in severe cases, prescribing a course of prednisone at 40 mg daily for 4 to 6 days followed by 20 mg for 4 to 6 days.7
eMedicine states that although oral systemic steroids, with a taper of prednisone over 10 to 14 days, are the standard for severe toxicodendron dermatitis, some authors suggest high-potency steroid creams twice daily for a week, then daily for a week.8
ACP Medicine states that most cases of allergic contact dermatitis are “effectively managed without use of systemic corticosteroids,” but that “short courses of systemic corticosteroids are indicated for patients with severe vesiculobullous eruptions of the hands and feet or face,” without describing duration or dose.9