What is the treatment for poison ivy?

Treatment for Poison Ivy Dermatitis

Immediately wash the exposed area with soap and water, commercial hand cleaners, or dishwashing soap—this removes 100% of poison ivy oils if done right away, but effectiveness drops to only 10% by 30 minutes. 1, 2

Immediate Decontamination (First Priority)

Time is critical for decontamination:

• Washing immediately removes 100% of urushiol oils 1, 2, 3
• Effectiveness drops dramatically: 50% at 10 minutes, 25% at 15 minutes, and only 10% at 30 minutes 1, 2, 3
• Remove all contaminated clothing, jewelry, and brush off dry plant material before washing 1, 2
• Commercial decontamination products, hand cleaners, or dishwashing soap produce 55-70% symptom reduction even when used up to 2 hours after exposure 1, 2, 4
• All three products (commercial decontamination, Goop, and dishwashing soap) show no significant difference in effectiveness 4

Treatment Algorithm Based on Severity

Mild to Moderate Cases

For localized dermatitis affecting <30% body surface area:

• Apply moderate-to-high potency topical corticosteroids (mometasone furoate 0.1% ointment or betamethasone valerate 0.1% ointment) twice daily to affected areas 2, 3
• Over-the-counter hydrocortisone has NOT been shown to improve symptoms in randomized trials 2, 3, 5
• Add oral antihistamines: non-sedating second-generation antihistamines (loratadine 10 mg daily) during daytime, or first-generation antihistamines (diphenhydramine 25-50 mg or hydroxyzine 25-50 mg) at night for sedation 2, 3
• Evidence for antihistamines relieving local itching is uncertain; they primarily help with sleep rather than itch relief 2, 3

Important caveat: While over-the-counter hydrocortisone is FDA-approved for poison ivy 5, clinical trials have not demonstrated efficacy, making prescription-strength topical corticosteroids the preferred first-line treatment 2, 3.

Severe Cases

For extensive dermatitis (>30% body surface area) or when self-care is limited:

• Initiate systemic corticosteroids immediately with prednisone 0.5-1 mg/kg body weight for 7 days, followed by a weaning dose over 4-6 weeks 2, 3
• Continue high-potency topical corticosteroids to affected areas 2, 3
• Add oral antihistamines for symptomatic relief 2, 3
• The corticosteroid taper MUST be long enough (4-6 weeks) to prevent rebound flare—this is a critical pitfall 2, 3

The combination of systemic corticosteroids and high-potency topical corticosteroids has been shown to reduce the duration of itching 1, 2, 3.

Second-Line Therapy for Refractory Pruritus

If antihistamines fail to control itching:

• Consider GABA agonists: pregabalin 25-150 mg daily or gabapentin 900-3600 mg daily 3

Supportive Care Measures

Apply these adjunctive therapies for symptom relief:

• Cool compresses to affected areas 1, 2, 3
• Oatmeal baths for widespread pruritus 1, 2, 3
• Alcohol-free moisturizing creams or ointments twice daily, preferably with urea-containing (5-10%) moisturizers 2, 3
• Apply sunscreen SPF 15 to exposed areas every 2 hours when outside 2, 3

Evidence supporting cool compresses and oatmeal baths is limited, but these interventions are low-risk 2, 3.

Critical Warnings and Pitfalls

Monitor for secondary bacterial infection:

• Check for increased warmth, tenderness, purulent drainage, honey-colored crusting, or cellulitis 2, 3
• These signs require antibiotic therapy 2, 3

Avoid these common mistakes:

• Frequent washing with hot water 2, 3
• Skin irritants including over-the-counter anti-acne medications, solvents, or disinfectants 2, 3
• Relying solely on over-the-counter hydrocortisone for anything beyond the mildest cases 2, 3
• Short corticosteroid tapers (<4 weeks) that lead to rebound flare 2, 3

Expected Course

Poison ivy dermatitis typically begins within days of exposure and lasts up to 3 weeks, with symptoms including redness, papules, vesicles, and itching proportional to the area and duration of contact 2, 6, 7.