Many a nature walk or camping trip has been ruined by allergic reactions to these poisonous plants. In fact, the National Institute of Allergy and Infectious Diseases (NIAID) estimates that, if exposed, 85 percent of Americans would experience an allergic reaction to these plants. That response can occur within hours of contact or may take days to appear. The itchy rash — a type of contact dermatitis — characteristic of an allergy to these plants is caused by a reaction to a substance in the plants called urushiol.
Telltale signs that you’ve rubbed shoulders with the wrong plant include a reddening of the exposed skin, followed by bumps and blisters, and often severe itching. After several days the blisters break and the oozing sores begin to crust over and disappear. A secondary bacterial infection may result from scratching the rash. In some cases, severe symptoms such as abscess, swollen glands and fever may develop.
A diagnosis can often be made based on the appearance and location of the rash and also by determining whether you’ve spent time outdoors in an environment where these plants thrive. In less obvious circumstances, your doctor can perform a kind of skin test called a patch test.
Washing with plain old soap and water is the first step in treatment. This removes the plant oil containing the allergen. In fact, if you wash all of the oil off the skin within 5 minutes of contact, it may be possible to avoid the allergic reaction. Clothes and any related camping or gardening equipment should also be washed. Don’t forget your dog — if you suspect that he came in contact with the plants, bathe him, too. Wet, cold compresses of water or diluted liquid aluminum acetate (Burow’s solution) may relieve any inflammation while the rash is still oozing. The old standby, calamine lotion, can bring some relief from itching and inflammation. Cool showers or soaking in a lukewarm bath with oatmeal or baking soda added are also time-honored, effective treatments.
When the allergic reaction is severe, a physician may prescribe stronger medicines to reduce itching and inflammation. These may include antihistamines to be taken by mouth and corticosteroids taken by mouth, by injection, or in lotions and creams to be applied to the skin.
The best line of defense is to learn to identify all three types of plants and then try to avoid them whenever possible, especially if you know you’re sensitive to them. All parts of the plants can release the allergen whether they are green or red, dead or alive. If you react strongly to these plants, you should also avoid other plants in the same family (Anacardiaceae or cashew), which includes cashew, mango, ginkgo, Japanese lacquer and Indian marking nut.
The information contained in or made available through This Site cannot replace or substitute for the services of trained professionals in the medical field. We do not recommend any treatment, drug, food or supplement. You should regularly consult a doctor in all matters relating to physical or mental health, particularly concerning any symptoms that may require diagnosis or medical attention.