Poison

By Peter Galvin, MD

There are three plants, namely poison ivy, poison oak, and poison sumac, that are frequently the cause of a red, itchy rash, medically called allergic contact dermatitis. The plants contain sap oil (urushiol) in their leaves, stems, and roots that is released on contact with the plant. The oil penetrates the skin, and once it is on the skin, it can be spread to other areas of the body by contact. People can also come into contact with urushiol by petting an animal that has the oil on its fur. Rarely, the oil can spread to other people through contact with clothing or objects, for example garden tools, that have urushiol on them.

Not everyone will have a skin reaction to urushiol, but about half to three-quarters of the population will react to it. In the U.S., there are about 10 to 50 million people who develop a rash from these plants every year. Those at highest risk include those who work outdoors, for example construction, forestry, and farm workers; landscapers; and firefighters (while fighting brush and forest fires). The rash from the three plants is red, bumpy, often has a streaky appearance, and is very itchy. In severe cases, fluid-filled blisters can develop. The rash usually appears 24 to 48 hours after contact with the plants, with peak severity from one to 14 days later. For those who were never exposed to urushiol, the rash may not appear for up to three weeks after contact. The rash normally resolves within one to three weeks.

For anyone who knows they were just in contact with the plants, they should wash their whole body with soap and water and scrub under their nails to remove the oil. Exposed clothing should be washed in warm, soapy water. Likewise, if they were accompanied by a pet, that pet should also be bathed. Topical treatments to help decrease symptoms include wet compresses, calamine lotion, oatmeal baths, and astringents (such as aluminum acetate) to dry a weeping rash. Steroid skin creams may reduce itching and blistering. Oral or injected steroids may be prescribed for those with severe blistering; a rash on the face, hands, or genitals; or involvement of more than 20% of the skin. Antihistamines do not reduce itching, but they may improve symptoms by causing sedation.

The key to prevention is to identify and avoid contact with these plants, often easier said than done. As you can see from the photo, poison ivy has three leaflets, poison oak has three to five leaflets, and poison sumac has seven to 13 pointed leaves. If you are planning to enter wooded or marsh areas, or even just clean out a weeded section of a yard, wear long pants, boots, long sleeves, and gloves. Also, a skin barrier cream, such as lotion that contains bentoquatam, may provide additional protection.

Please direct questions and comments to editor@rockawaytimes.com