Clarify the Role of OTC and Rx Options for Poison Ivy

Patients will ask you how to manage poison ivy, oak, and sumac.

Emphasize washing the area ASAP with soap and water...and cleaning anything (clothes, pet fur, etc) that contacted the plant.

Explain that urushiol, the allergenic oil, sticks to surfaces for long periods of time and can spread...but the rash is not contagious.

Don’t rely on topical cleansers (Tecnu, Zanfel, etc) after exposure...they’re costly and aren’t proven to work better.

For mild symptoms (itching, dry or weeping rashes, etc), suggest astringents (Domeboro, etc), calamine lotion, or oatmeal baths.

Also consider cool compresses or topical analgesics (menthol, camphor, etc) to help with discomfort or itching.

Tell patients that it’s okay to try OTC hydrocortisone for mild symptoms...but it’s too weak for more severe cases.

Explain that oral antihistamines aren’t likely to relieve itching...since the reaction isn’t histamine-mediated. But they may help the patient sleep.

Don’t recommend topical diphenhydramine, antibiotics (neomycin, etc), or “caine” anesthetics (benzocaine, etc). They don’t seem to help and may increase skin irritation.

For moderate to severe symptoms, suggest a medium- or high-potency Rx topical steroid (betamethasone, etc). For best results, advise starting one before vesicles form.

Consider an oral steroid for widespread or severe cases...such as when the rash covers more than 20% of the body or affects sensitive areas (face, genital, etc).

Recommend starting with prednisone 0.5 to 1 mg/kg, up to 60 mg/day...and decreasing the dose over 2 to 3 weeks.

Don’t suggest a methylprednisolone dose’s too short and can lead to rebound symptoms.

For prevention, advise not to rely on barrier products (Ivy X Pre-Contact, etc)...there’s no proof they work.

Key References

  • Cutis. 2022 Nov;110(5):270-273
  • Dermatitis. 2019 May/Jun;30(3):183-190
  • Mospan CM. Contact Dermatitis. In: Krinsky DL, Ferreri SP, Hemstreet BA, et al, Eds. Handbook of Nonprescription Drugs: an Interactive Approach to Self-Care. 20th ed. Washington, DC: American Pharmacists Association; 2021
Pharmacist's Letter. June 2023, No. 390608

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