How to Treat Poison Sumac

Poison sumac (Toxicodendron vernix) has plenty in common with cousins poison ivy (Toxicodendron radicans) and poison oak (Toxicodendron diversilobum), despite the fact that it looks completely different. In terms of presentation, poison sumac deviates greatly from the others because it typically has between seven and 13 leaves, all arranged in pairs, all on either side of a branch. This woody shrub also sports berries that can appear cream-colored, light yellow or simply glossy. The leaves are smooth-edged, and the plant can grow as a bush or even a tree.

Adding to the confusion is the fact that the three poisonous plants inhabit many of the same areas. Poison ivy (either the Eastern or Western variety) can be found virtually everywhere in the United States and as far north as the Canadian border, whereas poison oak sticks pretty much to the Pacific Northwest and the entire South. Poison sumac extends as far west as Texas and as far north as Canada, with the entire eastern seaboard affected. Michigan, Minnesota and Illinois make up the rest of the plant's western border. So, if you live in California you don't really have to fear the sumac, but definitely keep an eye out for the other two.

Poison sumac might look harmless enough, but it features a sap oil called urushiol, which can cause significant allergic reaction. Exposure can occur in a few different ways, such as direct contact when a person touches the plant itself, or by touching other items (like tools or clothes) that have the sap oil on them. The chemical can actually stay active, and thus problematic for a year or even longer. Never use poison sumac as a fire starter, as lung irritation can occur if the smoke is inhaled. This can cause major breathing problems, particularly in people who have preexisting respiratory issues.

Most symptoms of poison sumac appear a day or two after exposure, usually as an itchy, blistery rash. It can take as long as a week to show up, however, and can stick around for a week or two.

Most cases of poison sumac exposure can be treated at home using over the counter medications, however occasionally doctors need to get involved.

First, if you know that you've come in contact with the plant, immediately take steps to remove the oil from your skin. This can be accomplished by simply washing with warm, soapy water as soon as possible. If you don't wash it off you can end up transferring the oils to other body parts and exacerbating the damage. Immediately wash all clothes (separately from others) and clean off any tools that may have been exposed.

Poison sumac rashes are bad enough on their own, but they can be made worse or get infected by scratching, so refrain from seeking sweet relief by way of fingernails. Never pop blisters, and if they pop on their own leave them alone.

Consult a doctor if the rash is extremely large, or if the itching is completely unbearable. In particular, children who have a rash on their face, genital area or on a large area of the body should be seen by a doctor, as steroid treatment (cream, oral or injection) might be necessary to help with swelling and itching.

Otherwise, most cases can be treated at home with the help of short baths or showers. Make sure they're not too hot, though, as the hot water will make itching more intense. Hydrocortisone cream, calamine lotion, oatmeal baths, cool compresses and antihistamine tablets can also help relieve itching.

Learn more about poison sumac, oak and ivy in "Poison Ivy, Poison Oak and Poison Sumac: Identification, Precautions, Eradication" by Donald Mundell Crooks. HowStuffWorks picks related titles based on books we think you'll like. Should you choose to buy one, we'll receive a portion of the sale.