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Poison sumac (Toxicodendron vernix) grows as a large shrub or a small tree. It is the largest of three related plants in the cashew family all of which can cause skin irritation, the other two being poison ivy and poison oak. The poison sumac is distinguished by having the appearance of an ornamental, with large, alternate, toothless leaves, attractive clusters of fruit that is white when ripe, and brilliant fall foliage coloration.
Poison sumac grows mainly in the eastern United States. It is found in the South in eastern Texas, Louisiana, Mississippi, Alabama, Georgia, Florida, South Carolina, North Carolina, and Maryland, Delaware, and in small areas of Tennessee, Virginia, and West Virginia. In the North, it makes small appearances in Minnesota, Illinois, and Maine, and is found more prominently in Wisconsin, Michigan, Indiana, Ohio, Pennsylvania, New Jersey, New York, Connecticut, Rhode Island, Massachusetts, New Hampshire, and Vermont.
Urushiol is one of the chemicals that causes the toxicity associated with poison sumac. Over 90 percent of all people are allergic to it, but some are more sensitive than others. The oil is potent for up to five years after release, so even a dead plant can cause poisoning. Symptoms may not occur until seven to ten days after exposure for the first-time sufferer.
Symptoms of contact can vary with the amount of exposure and the number of times one has previously been exposed. Possible symptoms include skin redness, itching and burning sensation, swelling, and blisters. If the toxin is swallowed or breathed, which can happen if the sumac is burned, the results may be life-threatening, and emergency treatment should be sought immediately.
Although the standard warning for poison ivy is about its leaves, poison sumac is more broadly toxic. Not only are the leaves toxic, but so are its flowers, fruit, twigs, bark, and sap. Sap stuck under the fingernails or sap residue on shoes, gardening tools, clothing, or pets can be transferred at a later date. As little as a nanogram of urushiol may be all that is needed to cause a rash.
Immediate washing with soap and water may prevent any reaction, but even an hour after contacting the toxin may be too late, although it will still prevent spreading. Any contaminated items that have come in contact with poison sumac, such as clothing, should be isolated and washed with hot, soapy water. Health care providers may recommend an antihistamine or steroid cream to help relieve itching.