How Long Does Poison Ivy Oil (Urushiol) Stay Potent?

Urushiol, the oily toxin in poison ivy, oak, and sumac, is notoriously persistent. Studies show it remains active on dead plants, clothing, and tools for years—even 17 months in dry or submerged conditions. Burning releases airborne particles that cause severe respiratory reactions. Composting may degrade it biologically, but research is inconclusive; shredding spreads sap and risks exposure.

Best disposal: bag and trash. Avoid backyard compost piles. If composting at scale, shred first (with PPE), ensure hot, active decomposition, and never use resulting mulch on food crops.

Key facts: Urushiol is in roots, stems, leaves, fruit (not pollen). Highest in spring/early summer. Not volatile, but mowing/shredding creates airborne risk. "Leaves of three, let it be" still holds.