Poison Ivy Treatment

The rash is an allergic contact dermatitis triggered by urushiol — an oily resin found in poison ivy, poison oak, and poison sumac. Urushiol binds to skin within minutes and provokes a delayed hypersensitivity reaction, so the rash typically appears 12–72 hours after exposure. It is not contagious person-to-person, but urushiol can persist for months on clothing, tools, gardening gloves, and pet fur, causing new rashes on later contact.

Uncomplicated rashes usually resolve in 1–3 weeks. Consider a visit if the rash covers more than about 10% of your body, involves the face, eyes, mouth, or genitals, is severely itchy or blistering, isn't improving after 7–10 days, or shows signs of bacterial infection (increasing pain, warmth, pus, fever). Widespread or severe reactions often benefit from a short course of oral corticosteroids.

OTC options — hydrocortisone 1% cream, oral antihistamines (cetirizine, loratadine, diphenhydramine), calamine lotion, and cool compresses — are enough for mild, localized rashes. Prescription-strength topical corticosteroids (triamcinolone, clobetasol) work faster on moderate rashes. Oral prednisone tapered over 2–3 weeks is reserved for severe or widespread cases; shorter courses often lead to rebound rash.

Wash exposed skin with soap and cool water as soon as possible — ideally within 30 minutes of contact; specialized urushiol removers (Tecnu, Zanfel) can help if used early. Launder clothing, hats, and shoelaces in hot water with detergent, and clean tools and gardening gloves with rubbing alcohol or soapy water. Bathe pets with pet-safe shampoo while wearing gloves, since urushiol trapped in fur is a common source of hidden re-exposure.

Topical corticosteroids can cause skin thinning with prolonged use — a concern mainly for high-potency products on the face or skin folds. Oral prednisone commonly causes insomnia, mood changes, increased appetite, and elevated blood sugar; longer or repeated courses raise the risk of bone loss and adrenal suppression. First-generation antihistamines like diphenhydramine cause significant drowsiness; second-generation options (cetirizine, loratadine, fexofenadine) are less sedating.