What Is Urushiol?

A man with poison ivy blisters on his hand.
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  • Written By: Harriette Halepis
  • Edited By: Bronwyn Harris
  • Last Modified Date: 02 April 2014
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Urushiol is a type of toxin that is usually found in plants. While organic, this toxin can cause skin irritation. Plants that commonly contain urushiol include poison oak, poison ivy, and sumac. Interestingly, some people contract urushiol-induced contact dermatitis due to confusion within the human body.

Urushiol has the ability to trick the human body into believe that it is under attack. As soon as the immune system senses an attack, T-cells that are inside of the blood release enzymes and toxins. T-cells are highly damaging to both good and bad cells. When the fluids released from the T-cells damage nerves, the result is itchy skin.

Urushiol can cause itching in humans, though it does not affect most animals. Birds, deer, goats, horses, and cattle all consume berries from toxic plants without harm. Curiously, 90% of all adults react negatively to toxic plants. At this time, scientists have not determined why some people are affected by urushiol, while others are not.

The part of a toxic plant that generally causes a reaction looks a lot like syrup. In fact, the name urushiol comes from the Japanese word urushi, which refers to a type of lacquer that is produced in East Asia from the sap of the kiurushi tree. The sap itself is not important to most toxic plants, though it does have an impact upon humans.


Poison ivy happens to be the one toxic plant that needs its sap to survive. When a poison ivy plant has been damaged, the plant releases its sap to help heal any wounds. Unfortunately for those that are allergic to poison ivy, this plant is highly sensitive. A simple brush against the plant will cause it to release its poisonous sap-like toxins.

There is a way to tell whether or not a poison ivy plant has been recently damaged. Plants that have released sap will appear shiny, or plant leaves may have small black spots on them. Poison ivy plants that appear shiny or spotted should be avoided. Then again, it's entirely possible to come in contact with toxic sap without ever entering a wooded area.

Toxic sap can be easily transferred from one person to another. In addition, an allergic reaction can occur if a person has come in contact with any item or animal that contains a toxic plant's oils. Dogs, cats, and even garden tools might contain enough of a plant's toxin to cause an allergic reaction. Lastly, the sap from toxic plants can be released into the air if these plants are used in order to create a campfire.


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