Here comes summer, bringing outdoor barbecues, swimming and sailing, but also sunburn, mosquito-borne illnesses and poison ivy.
Let’s focus today on the itchy rash that plagues so many.
Poison ivy, poison oak and poison sumac share the same sap oil, urushiol, in their roots, stems and leaves. The oil is colorless and odorless, so it may not be obvious that you have it on your skin. You can spread it from one part of your skin to another without knowing it.
About 2/3 of adults develop dermatitis after getting urushiol on their skin, typically 1-2 days after contact, though it may be delayed if a first contact.
The rash is red and bumpy and intensely itchy, and is often in streaks, reflecting brushing against the plant. If severe, blisters may develop. The rash typically clears in 2-3 weeks.
Treatment is for symptoms, not cure, and includes wet compresses, calamine lotion and topical steroid creams. If it is very extensive or involves sensitive areas like the face or genitals, oral steroids can be prescribed.
Much better is prevention. If you think you have been exposed, wash your entire body with mild soap; water alone will not remove the oil, which penetrates the skin. Use a soapy brush under the nails. Wash any clothing that may have contacted the oil in warm soapy water.
Pets can carry the oil on their fur and pass it to you when you touch them, so bathe them if they have run through the plants.
Best, of course, is to avoid contact!
Poison ivy usually has three broad, tear-shaped leaves. It can grow as a climbing or low-spreading vine that sprawls through grass and often grows along rivers, lake fronts and ocean beaches. It is found everywhere in the continental U.S.
Poison oak has leaves that look like oak leaves and it grows as a vine or a shrub. The plant can have 3 to 5 leaflets per group. It is most common in the western U.S.
Poison sumac has seven to 13 leaflets per stem that are characterized by smooth surfaces and pointed tips. It is most often found in wooded, moist areas of the southern U.S.
Summer will be a lot more fun without the itch!
Edward Hoffer MD is Associate Professor of Medicine, part-time, at Harvard.
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