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Physical Information

Name: Urushiol

Use: none

Source: Poison Ivy, Poison Oak, Poison Sumac

Recommended daily intake: none (not essential)

Absorption: skin (direct and indirect), airborne,

Sensitive individuals: children (small size), previously sensitized

Toxicity/symptoms: severe itching, redness, swelling, then blisters

Regulatory facts: none

Recommendations: avoid, protect against contact, herbicides

Urushiol Structure

Retrieved from San Francisco State University


Pharmacology and Metabolism

Poison Oak

Urushiol is an oil, made up of a particular class of chemicals and produced by the plants poison ivy, poison oak, and sumac. Urushiol is produced by the plant for protection. The allergens are located on the outside of the plant. The oil is colorless or a pale yellow color that is secreted from any cut or crushed part of the plant (such as the roots, stem or leaves). Once the allergen has been exposed to air, it turns a dark brown/black color. This color can help to identify the toxin/toxic plant.

For an allergic-type response, it is not the first contact that produces the reaction but rather the next contact - BE CLEARER ABOUT THIS PART - WHAT IS THE "NEXT CONTACT". Specifically, once a person has come into skin contact (either direct or indirect) with this allergen, the skin usually swells and becomes red, producing an intense rash and later on blisters. The rash does not spread by contact but by absorption. Therefore, allergic reactions in areas with thicker skin (such as legs and forearms) tend to spread more slowly than reactions in areas with thinner skin (such as the stomach). Also, if the plant is burning, urushiol can be inhaled.

Health Effects

Sensitivity varies from person to person, tough urushiol produces a allergic reaction in more than 70% of people. Small children are the most sensitive to the toxin and only about 15% of people appear to be resistant. The rash is usually organized in streaks or lines. After the blisters crust over, the rash takes at least 10 more days to heal. It is best to prevent contact with the plants emitting this toxin by wearing long pants and shirts in areas where the plants can be found. These urushiol containing plants are most common during the spring and summer. During the fall the leaves can turn reddish colors. It is also important to note that the urushiol does not dry and sticks to most surfaces.


If you think you have come into contact with urushiol, wash all contaminated areas with soap and water as well as all clothes that may be affected. To relieve the itching, take cool showers and apply the infected area with anti-itching cremes such as calamine lotion.


American Academy of Dermatology. Public Resource Center - Poison Ivy, Oak, and Sumac. Accessed 8-15-07.

Gilbert, Steven. A Small Dose of Toxicology. CRC Press: 2004.

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