What is the management of poison ivy (Toxicodendron radicans)?

Management of Poison Ivy Dermatitis

For mild to moderate poison ivy dermatitis, apply prescription-strength topical corticosteroids (mometasone furoate 0.1% or betamethasone valerate 0.1% ointment) twice daily, and for severe cases or involvement of >30% body surface area, initiate systemic prednisone 0.5-1 mg/kg daily for 7 days followed by a 4-6 week taper to prevent rebound flare. 1, 2

Immediate Post-Exposure Decontamination

Time is critical for preventing or minimizing the reaction:

• Wash with soap and water immediately after contact, which removes 100% of urushiol oil if done right away, but effectiveness drops rapidly: 50% at 10 minutes, 25% at 15 minutes, and only 10% at 30 minutes 1, 2
• Remove all contaminated clothing, jewelry, and brush off any dry plant material before washing 2
• Commercial decontamination products or dishwashing soap can reduce symptoms by 55-70% even when used up to 2 hours after exposure 1, 2

Treatment Algorithm by 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, 2
• Do not use over-the-counter hydrocortisone preparations, as randomized trials have shown they do not improve symptoms 1, 2
• Add oral antihistamines for pruritus: 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 bedtime for their sedative properties 1, 2
• Note that antihistamines may primarily help with sleep rather than directly relieving itch 2
• Consider GABA agonists (pregabalin 25-150 mg daily or gabapentin 900-3600 mg daily) as second-line therapy if antihistamines fail to control pruritus 1

Severe Cases (>30% Body Surface Area or Significant Functional Impairment)

• 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, 2
• Continue high-potency topical corticosteroids to affected areas 1, 2
• Add oral antihistamines for symptomatic relief 1, 2
• The 4-6 week taper is critical to prevent rebound flare, which is a common pitfall when shorter courses (1-13 days) are prescribed 1, 3

Supportive Care Measures

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

Critical Pitfalls to Avoid

Inadequate Steroid Duration

• Shorter duration oral corticosteroids (1-13 days) significantly increase the risk of return visits (OR 1.30), with most patients requiring at least 14 days and preferably 4-6 weeks of treatment 1, 3
• Emergency department patients may present with more severe disease and particularly benefit from longer tapers 3

Secondary Bacterial Infection

• Check for signs of superinfection: increased warmth, tenderness, purulent drainage, honey-colored crusting, or cellulitis 1, 2
• These findings require antibiotic therapy in addition to anti-inflammatory treatment 1, 2

Underestimating Severity

• Systemic corticosteroids are necessary when >30% body surface area is involved or when self-care is limited 1
• Patients initially treated in the ED have higher return rates compared to those treated by primary care or dermatology, suggesting possible undertreatment in emergency settings 3