Causes

Poison ivy rash is caused by an allergic reaction to an oily resin called urushiol. It's found in poison ivy, poison oak and poison sumac. This oily resin is very sticky, so it easily attaches to your skin, clothing, tools, equipment and pet's fur. You can get a poison ivy reaction from:

• Touching the plant. If you touch the leaves, stem, roots or berries of the plant, you may have a reaction.
• Touching contaminated objects. If you walk through some poison ivy and then later touch your shoes, you might get urushiol on your hands. You might then transfer it to your face or body by touching or rubbing. If the contaminated object isn't cleaned, the urushiol on it can still cause a skin reaction years later.
• Inhaling smoke from the burning plants. Even the smoke from burning poison ivy, poison oak and poison sumac can irritate or harm your nasal passages or lungs.

Pus that oozes from blisters doesn't contain urushiol and won't spread the rash. But it's possible to get poison ivy rash from someone if you touch plant resin that's still on the person or contaminated clothing.