Treatment of Poison Ivy Dermatitis
For poison ivy dermatitis, use topical high-potency corticosteroids (such as clobetasol propionate 0.05%) twice daily for mild to moderate cases, and add oral corticosteroids with a 15-day taper (not a short 5-day course) for severe cases involving >30% body surface area or significant functional impairment. 1, 2
Severity-Based Treatment Algorithm
Mild Cases (Grade 1: <10% BSA)
- Topical high-potency corticosteroid twice daily (e.g., clobetasol propionate 0.05%) 1
- Hydrocortisone is FDA-approved specifically for poison ivy and provides symptomatic relief of itching and inflammation 1
- Reassess after 2 weeks; if no improvement, escalate treatment 3
Moderate Cases (Grade 2: 10-30% BSA or limiting daily activities)
- Continue topical high-potency corticosteroid twice daily 3
- Consider adding oral corticosteroids if symptoms significantly limit instrumental activities of daily living 3
- Monitor for signs of secondary bacterial infection: increased warmth, purulent drainage, honey-colored crusting, or cellulitis 3
Severe Cases (Grade 3: >30% BSA or limiting self-care)
- Oral prednisone with a 15-day taper regimen 2:
- Days 1-5: 40 mg daily
- Days 6-7: 30 mg daily
- Days 8-9: 20 mg daily
- Days 10-11: 10 mg daily
- Days 12-15: 5 mg daily
- Plus topical high-potency corticosteroid twice daily 3, 1
Critical Evidence on Steroid Duration
The most important clinical decision is steroid course length. A 15-day tapered course is superior to a 5-day short course for severe poison ivy 2. While both regimens showed similar rates of rash return and side effects, the longer course significantly reduced the need for additional medications (22.7% vs 55.6%, number needed to treat = 3.05) 2. This prevents return visits and reduces exposure to multiple over-the-counter medications 2.
Expected Timeline and Monitoring
- Natural course: dermatitis typically clears within 1-3 weeks without continued allergen exposure 4, 5
- Reassess at 2 weeks: worsening or lack of improvement may indicate continued allergen exposure or complications 3
- Document all prior treatments attempted and their effectiveness 3
Common Pitfalls to Avoid
- Do not use short 5-day steroid courses for severe cases - they lead to higher rates of additional medication use and potential return visits 2
- Watch for "angry back syndrome" when multiple body areas are affected, which can complicate assessment 3
- Screen for secondary bacterial infection - failure to respond to treatment, painful lesions, pustules on arms/legs/trunk, or yellow crusting warrant bacterial culture and antibiotics 3
- Ensure complete allergen removal - persistent exposure is the most common cause of treatment failure 4, 5