What is the treatment for a patient suspected of having come into contact with poison ivy?

Treatment of Poison Ivy Dermatitis

For patients suspected of contact with poison ivy, immediately wash the exposed area with soap and water—this removes 100% of urushiol oils if done right away, but effectiveness drops to 50% at 10 minutes and only 10% at 30 minutes. 1

Immediate Decontamination (First Priority)

• Remove all contaminated clothing, jewelry, and brush off any dry plant material before washing 2
• If immediate washing isn't possible, commercial decontamination products, hand cleaners, or dishwashing soap can still reduce symptoms by 55-70% even when used up to 2 hours after exposure 1, 2
• Time is critical—every minute of delay significantly reduces decontamination effectiveness 1

Treatment Algorithm Based on Severity

Mild to Moderate Cases

Apply moderate-to-high potency topical corticosteroids (mometasone furoate 0.1% ointment or betamethasone valerate 0.1% ointment) twice daily to affected areas. 1, 3

• Over-the-counter hydrocortisone has NOT been shown to improve symptoms in randomized trials, despite FDA approval for this indication 1, 3, 4
• 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 1, 3
• Evidence for antihistamines relieving local itching is uncertain—they primarily help with sleep rather than itch relief 1, 3
• Consider GABA agonists (pregabalin 25-150 mg daily or gabapentin 900-3600 mg daily) as second-line therapy if antihistamines fail 3

Severe Cases (>30% body surface area or significant facial/genital involvement)

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. 1, 3

• Continue high-potency topical corticosteroids to affected areas 1, 3
• Add oral antihistamines for symptomatic relief 1, 3
• The corticosteroid taper MUST be long enough (4-6 weeks) to prevent rebound flare—this is a critical pitfall. 1, 3
• Prescription-strength topical corticosteroids combined with systemic steroids have demonstrated efficacy in reducing itch duration 1, 3

Supportive Care Measures

• Apply cool compresses to affected areas for symptomatic relief 2, 3
• Consider oatmeal baths for widespread pruritus 1, 2, 3
• Use alcohol-free moisturizing creams or ointments twice daily, preferably with urea-containing (5-10%) moisturizers 1, 3
• Avoid frequent washing with hot water and skin irritants including over-the-counter anti-acne medications, solvents, or disinfectants 1, 3
• Apply sunscreen SPF 15 to exposed areas every 2 hours when outside 1, 3

Critical Warning Signs Requiring Antibiotic Therapy

Check for secondary bacterial infection: increased warmth, tenderness, purulent drainage, honey-colored crusting, or cellulitis—all require antibiotic therapy. 1, 3

Common Pitfalls to Avoid

• Delaying washing after exposure—effectiveness drops dramatically within minutes 1, 2
• Using only over-the-counter hydrocortisone for anything beyond very mild cases—it lacks evidence of efficacy 1, 3
• Prescribing too short a systemic corticosteroid taper (less than 4-6 weeks)—this causes rebound flare 1, 3
• Relying on antihistamines alone for itch relief—they primarily provide sedation, not local itch control 1, 3