Poison Ivy Cross-Reactors

Poison ivyDeveloping an itchy rash after a hike in the woods or a day of working in the yard is not particularly surprising. An inadvertent brush with poison ivy or poison oak and the annoyingly itchy rash that develops is a common summertime problem in the Eastern US. But developing similar symptoms after preparing a fresh meal in your kitchen seems unexpected. As it turns out, it’s not so rare.

People who are sensitive to poison ivy have developed an allergic reaction to one of the plant’s compounds, urushiol, found within the sap. Once exposed, people can develop an allergy evidenced by the itchy, blistering rash (allergic contact dermatitis) that develops upon subsequent exposures. 

But you may develop an outbreak of poison ivy rash without even being exposed to the plant. If you are allergic to urushiol and come in contact with other plants in the same family (Anacardiaceae), you may experience an outbreak. In people sensitive to poison ivy, such cross-reactions commonly occur with exposure to mangoes, where contact with the skin can induce an allergic contact dermatitis. Because the urushiol toxin is found only in the skin of the fruit, sensitivities would be apparent in the person peeling and preparing it. Eating mango flesh is not dangerous and would not provoke an outbreak.

Other less commonly encountered cross-reactors include the Ginkgo biloba tree, Japanese lacquer tree, cashew shell oil, and the Indian marking tree.

Skin reactions to poison ivy, poison oak, poison sumac, and the cross-reactors listed above can be robust, often requiring prescription medications from a doctor. For mild eruptions, topical steroid creams can help to reduce the duration and discomfort associated with the rash. For more extensive eruptions, oral steroids are often required for effective management.

If you are sensitive to poison ivy, be aware of your exposure to common potential cross-reactors – and have someone else prepare the fresh mangoes for breakfast.

Published on 08/10/2009 | Last updated on 10/18/2018