Is prednisone (corticosteroid) effective for treating poison ivy reactions?

Systemic Prednisone for Poison Ivy: Treatment Recommendations

For severe poison ivy dermatitis (>30% body surface area or limiting self-care), initiate oral prednisone 0.5-1 mg/kg daily with a prolonged taper over 4-6 weeks to prevent rebound flare. 1

Treatment Algorithm by Severity

Mild to Moderate Cases (<30% BSA)

• Start with topical corticosteroids as first-line therapy: moderate-to-high potency steroids (mometasone furoate 0.1% ointment or betamethasone valerate 0.1% ointment) applied twice daily to affected areas 1
• Add oral antihistamines for pruritus: loratadine 10 mg daily during daytime, or diphenhydramine 25-50 mg or hydroxyzine 25-50 mg at bedtime 1
• Note the evidence limitation: Over-the-counter hydrocortisone preparations (0.2%-2.5%) have NOT been shown to improve symptoms in randomized trials 2
• Only prescription-strength topical corticosteroids combined with systemic steroids have demonstrated efficacy in reducing itch duration 2

Severe Cases (>30% BSA or Limiting Self-Care ADL)

This is when systemic prednisone becomes essential:

• Initiate prednisone 0.5-1 mg/kg body weight immediately 1
• Critical dosing duration: Continue for 7 days at full dose, then taper over 4-6 weeks total 1, 3
• Continue high-potency topical corticosteroids to affected areas 1
• Add oral antihistamines for symptomatic relief 1

Why the Long Taper Matters

• A 15-day course (5 days full dose + 10-day taper) significantly reduced need for additional medications compared to 5-day short course (22.7% vs 55.6%, NNT=3) 3
• Short courses risk rebound flare when symptoms can last up to 3 weeks naturally 2
• The 4-6 week taper prevents premature discontinuation before the allergic reaction fully resolves 1

Supportive Care (All Severity Levels)

• Apply alcohol-free moisturizing creams with 5-10% urea twice daily 1
• Use cool compresses for symptomatic relief 2
• Consider oatmeal baths for widespread pruritus 2
• Avoid hot water washing and skin irritants (anti-acne medications, solvents, disinfectants) 1

Second-Line Options for Refractory Pruritus

If antihistamines fail to control itching despite adequate dosing:

• Pregabalin 25-150 mg daily or gabapentin 900-3600 mg daily 1

Critical Pitfalls to Avoid

1. Inadequate steroid taper length

• Ensure 4-6 week total duration to prevent rebound 1
• Do not use 5-7 day "dose packs" for severe cases 3

2. Missing secondary bacterial infection

• Check for increased warmth, tenderness, purulent drainage, honey-colored crusting, or cellulitis 1
• These require antibiotic therapy in addition to corticosteroids 1

3. Relying on over-the-counter topical steroids alone

• OTC hydrocortisone (even up to 2.5%) lacks evidence of efficacy 2
• Prescription-strength topicals are necessary for documented benefit 2

4. Underestimating severity

• If >30% BSA involved or self-care activities limited, systemic steroids are mandatory, not optional 1

Post-Exposure Prevention (If Caught Early)

• Washing with soap and water removes 100% of urushiol if done immediately, 50% at 10 minutes, 25% at 15 minutes, and only 10% at 30 minutes 2
• Commercial decontamination products, hand cleaners, or dishwashing soap used within 2 hours reduce symptoms by 55-70% 2, 4
• Cost-effective options (dishwashing soap, Goop) perform similarly to expensive commercial products 4