Common Myths and Truths About Poison Ivy, Poison Oak, and Poison Sumac

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Myth #1: These plants are poisonous.
Truth: Poison ivy, poison oak, and poison sumac are all members of the Toxicodendron genus. All members of this group produce chemicals in their plant juices to which most human beings are able to develop a brisk allergic response. The first time one comes into contact with these chemicals there is generally no reaction but the immune system is stimulated to develop the capacity to recognize the molecule the next time a contact occurs.

Myth #2: One must come into direct contact with the plant to develop a rash.
Truth: Generally direct contact with plant juice is required. Occasionally reactions can occur if this juice is transferred indirectly onto the skin of a sensitive individual (for example, from the fur of a pet or clothing that has been contaminated with the plant oils). Sometimes blowing wind, especially soon after a brushfire, can contain enough chemical to cause a rash in very sensitive people.

Myth #3: The appearance of the rash is characteristic for Toxicodendron dermatitis.
Truth: There is nothing specific about the appearance of the eruption. Any other plant allergic contact dermatitis could potentially appear identical. The rash appears as red, itchy bumps and small blisters often distributed in a linear fashion on exposed surfaces. When the blisters rupture, there can be weeping and oozing.

Medically Reviewed by a Doctor on 12/9/2014