She comes on like a rose
But everybody knows
At night, when you are sleeping
Poison ivy comes creeping.
Ivy is as pretty as a daisy
But look out! She’s crazy.
She will really do you in
If she gets under your skin.
Then you’ll need an ocean
Of calamine lotion,
Or a magic potion
To calm the commotion. *
* Based on a song, Poison Ivy, by Jerry Lieber and Mike Stoller
And Ivy may be getting more vindictive. Rising carbon dioxide levels (currently about 400 parts per million of air) produce plants that are on average 50% to 75% more potent and grow twice as fast compared to plants grown under simulated carbon dioxide levels of the 1950s (300 parts per million of air).
Here what you should know:
1. The plant is a chameleon. The old saying “If the leaves are in three, let them be” helps identify the majority of plants but, in fact, the plant may have more than three leaves and their shape and color vary greatly depending upon the exact species encountered, local environment and season. Plants may have yellow or green flowers and white to green-yellow or amber berries. Moreover, many non-poisonous plants fit the description of poison ivy.
2. Know your poison. The rash-causing chemical is an oily substance, urishiol, which is present in the entire plant – leaves, stem and roots – and remains viable in dead plants. Some people appear more susceptible to the oil than others but few are immune. Infants rarely get severe cases; likely it takes repeated exposure to become sensitized. Exposure to 50 micrograms of urushiol, an amount contained in less than one grain of table salt, cause rashes in 80 to 90 percent of adults.
3. Urishiol is rapidly absorbed into the skin. The damage is done in less than an hour of contact. Wherever the oil touches the skin, a rash may appear. The more oil touching the skin, the sooner the rash appears and the more severe it is.
Rarely, poison ivy is contacted indirectly. Urishiol remains potent far longer on shoes, clothing, toys, garden tools, and on coats of pets than on skin. Wear gloves to wash these items after possible exposure. Avoid inhaling smoke from burning weeds or wildfires. Inhaling urishiol irritates the lungs, a major hazard to forest firefighters.
4. Immediate action may prevent or lessen the rash. If you suspect exposure, wash the area immediately and thoroughly with soap and water and brush fingernails. Within 10 minutes 50% of the oil is absorbed into the skin, and by 30 minutes, all is absorbed. Over-the-counter products, Tecnu Ivy Scrub and Zanfel Poison Ivy Wash, for example, accelerate the removal of oil and, say the manufacturers, may remove oil already bound to the skin. These products are recommended only for children older than six years of age, though there are no known harmful effects in younger children. Read labels.
5. The rash usually consists of pinhead-sized, fluid-containing blisters. The blisters are often in streaks, the result of oil-covered fingers touching the skin. Depending on the amount of oil present and the sensitivity of the victim to the oil, the rash may appear any time from four hours after contact until several days later, and may remain for several weeks.
6. The rash is not contagious to others. The blister fluid is the body’s reaction to the plant; it does not contain oil. Scratching cannot spread the rash to other parts of the body. Subsequent appearance of the rash on new areas of skin is the result of less urushiol having contacted that area or is due to new exposures.
7. Prepare children for the outdoors. Poison ivy is found throughout the United States (except in California, Alaska and Hawaii) and in southern Canada, but nowhere else in the world. It tends to grow in forests, fields, wetlands, along streams and roads, and in urban areas such as parks and backyards. Check playing areas for plants, especially peripheries of sandlot baseball fields. Teach older children to recognize the plant. Tell children not to touch vegetation unnecessarily. Wearing clothing with long pants and sleeves and high socks minimizes exposure. Gloves add protection (but are not practical).
8. Various medications reduce itching. Try cool water compresses or substances containing hydrocortisone or phenol and menthol. Not recommended are topical antihistamines or anesthetics (“caine” products, for example). These cause rashes in some individuals. Oral antihistamines reduce itching but have side effects. Read directions. Severe cases require medical attention, possibly treatment with oral cortisone. In the wilderness, try soap, shaving cream or other soothing substances – even smearing the inside of banana peels on itchy areas. Attempts at desensitization are ineffective. Keep rashes clean with soap and water and apply antibiotic ointments to prevent secondary infections.
9. Two other plants contain urishiol: poison oak and poison sumac. The rashes of all three “poisons” are identical, as is the treatment. Typically poison oak grows as a shrub with leaves of three similar to poison ivy but Pacific poison oak may be vine-like. Both types may have yellow or green flowers and clusters of green-yellow or white berries – the berries very similar to those of poison ivy.
Poison sumac is a woody shrub that has stems that contain 7-13 leaves arranged in pairs, often with glossy, pale yellow, or cream-colored berries.
Abundant along the Mississippi River and boggy areas of the Southeast
10. Preventing the “poisons.” Tecnu Ivy Block, for example, prevents the urishiol from reaching the skin. Apply at least fifteen minutes before exposure and remove with soap and when protection is no longer needed. Protection lasts four hours. No prescription is required. Tecnu is not recommended for children less than six years of age, though no data say it is harmful for younger children. Tecnu has no effect on rashes already present.
