A 60-year-year-old woman presented with a severely pruritic rash that had begun 4 days prior. The rash had started on her chest and arms and spread to involve her face, neck, abdomen, and legs. Physical examination revealed multiple scattered vesicles, bullae, and erythematous plaques grouped in a linear arrangement, with some lesions having overlying crust. Further history revealed that the patient had been gardening 4 days prior and had removed a plant with 5 leaves attached to a vine.
Distinguishing Virginia Creeper from Poisonous Plants
Virginia creeper exposure in a susceptible individual presents with symptoms that are clinically indistinguishable from those associated with exposure to poison ivy or poison oak. Virginia creeper is a climbing vine, the leaflets of which are red when they first emerge but turn green as they mature. While urushiol is known to be the allergen in Toxicodendron species, the primary allergen in Virginia creeper is unknown. Oxalate crystals are found in Parthenocissus plants; however, these crystals are mostly known for causing an irritant reaction after ingestion.
Summertime usually means more time outdoors, where there is an increased risk of experiencing a brush with poison ivy (Toxicodendron radicans), poison oak (T. pubescens), or poison sumac (T. vernix). Knowing what to look for can help you avoid these toxic plants. The leaves of poison ivy and poison oak have three leaflets, which is where the adage "leaves of three, let it be" comes from. The leaflets are commonly 2 to 8 inches long and 3⁄4 to 5 inches wide, and they have scattered, jagged teeth along the edges. The teeth on the leaflets of poison oak tend to be more rounded, while those of poison ivy are more pointed. Poison ivy grows as a vine that may run along the ground or up the sides of trees, houses, or other vertical surfaces. The vines can reach more than 2 inches in diameter. Larger vines often appear “hairy” due to tiny roots that extend from the vine. In contrast, poison oak is more shrub-like, and its leaves often are crowded near the tips of upright stems, which can reach 3 feet tall. Poison ivy is found in a wide variety of habitats but is especially common in wooded areas, along forest edges, and in urban green spaces.
Poison sumac is a close relative of poison ivy and poison oak, but it looks very different. Poison sumac leaves have seven to fifteen leaflets that are commonly 2 to 4 inches long and 3⁄4 to 2 inches wide. The leaflets, which are arranged along the stem in pairs, are oblong with sharply pointed tips and smooth or somewhat wavy edges. The stems and leaf stalks often are a bright red color. Poison sumac grows as a shrub or small tree, reaching up to 20 feet tall, and is typically found only in open or wooded swampy areas.
Virginia creeper (Parthenocissus quinquefolia) and poison ivy often grow together and are frequently confused with each other. Young Virginia creeper leaves or those that have been damaged may occasionally have three leaflets, but most have five. Plants of both species often have a reddish center where the leaflets join. Another difference between the two is that Virginia creeper vines are much less hairy than poison ivy vines. Virginia creeper has fewer, more widely spaced rootlets, and some rootlets have small attachment disks at the ends. Only rarely does contact with Virginia creeper leaves or stems cause an allergic reaction in sensitive individuals.
Box elder (Acer negundo) seedlings have leaves with three leaflets and can look like poison ivy at first glance. Fragrant sumac (Rhus aromatica) is often mistaken for poison oak, and both grow in similar habitats. One difference is that the leaflets of fragrant sumac are attached at a single point, while the terminal leaflet of poison oak has a short stem. Smooth sumac (Rhus glabra) and winged sumac (Rhus copallinum) are commonly occurring shrubs that may be mistaken for poison sumac, but there are several clear differences. The leaflets of smooth sumac have teeth along the edges and are greater in number (eleven to thirty-one) than those seen in poison sumac. Winged sumac is easily identified by the leafy wings along the leaf stalk. Neither species is likely to cause skin irritation, although some people may be sensitive to the sap.
Understanding Plant Dermatitis and Contagiousness
Touching any of the three poisonous species (poison ivy, oak, or sumac) may result in a red, swollen, and painful rash of itchy blisters. About 85 percent of people are allergic to urushiol, the oily compound responsible for the skin reaction. Urushiol is found in all parts of these plants. Simply touching the leaves may expose you to the oil, and additional oil is released when plant parts are crushed or damaged. The oil resists breakdown and may cling to clothing, tools, and pet fur for long periods of time, even a year or more.
Not everyone is allergic to these plants, and sensitivity varies between people, but allergies may develop with increased contact. People suffering from a rash caused by these plants need not worry about spreading it to other parts of the body or to other individuals. After the rash appears, it is not contagious. Any observed spreading of the rash is the result of a delay in reaction from previous exposure or from re-exposure due to contact with clothing and equipment that has not been properly cleaned.
If you have a poison ivy rash on your arm, you cannot spread it to your leg by scratching. Breaking the blisters and then touching another part of your body does not spread the rash. This misperception occurs in part because new blisters and irritated areas can appear more than a week after exposure to the oils. But these merely represent the lag time after initial contact. Poison ivy is not contagious; you cannot give it to someone else unless they come into contact with the oils that are on your body or your clothes after you encountered the plant.
An example of re-exposure: Let's say you took a hike and unknowingly walked through poison ivy. Now the oil is on the bottom of your pants and maybe your socks and even on your sneakers or hiking boots. So you get home and take these off. A day or so later you get the first rash. Boy is it itchy! The next day you put on your sneakers, touching the laces as you do. The next day, you have MORE poison ivy! Then, a week later you decide to wear those pants again, and putting them on, rub against some of the oil that is on them. A day later, you get a new rash, just as itchy! The next day you do laundry. As you are putting things into the washer, you touch the socks you had on that hike, the same ones with the oil on them and guess what? The next day you get a new rash-this time on your hand! The oil from the poison ivy and poison oak plant is very potent. A wife or mother who gets the poison ivy rash and has never even been outside may be getting it from doing laundry from a person who has had contact with the plant and the oil. Also, a person who seems to be immune to the rash can suddenly lose this immunity and get the rash. Being immune today doesn’t mean you will always be immune.
A person can be affected by any part of a poison ivy plant at any time of year, even a leafless vine in winter. Yes, some people react if they come in contact with the sap of Virginia creeper. The rash cannot be distinguished from that caused by poison ivy or poison oak. Differences between poison ivy and poison oak are subtle and do not really matter in identifying the plants. Both have three leaves on each stem, a red coloration at the apex where the three leaves connect and produce oils that make some people itch. Some botanists claim that poison oak is more virulent than poison ivy; others disagree. Someone itching from exposure to either plant does not care that the other one might have been worse. Poison ivy can be a single plant or a hairy vine clinging to a tree. Leaves, stem, fruits, and roots all produce oils that can cause skin irritation. Patting a dog that has just walked through poison ivy can cause a problem. You can even get poison ivy internally by inhaling oil droplets that become airborne in smoke when the plants are burned.
Treatment and Prevention of Plant Dermatitis
Treatment of phytodermatitis from Virginia creeper, like that of poison ivy, primarily involves oral and topical corticosteroids. This treatment is often combined with antihistamines if the patient continues to experience pruritus, although antihistamines are generally not effective for the pruritus associated with allergic contact dermatitis. Typically, the rash resolves within 1 to 3 weeks, and patients do not require further monitoring.
In mild cases, hydrocortisone creams or other anti-itch creams can be applied to soothe irritation. Some products are marketed specifically for treatment of poison ivy and poison oak rashes and can be obtained over-the-counter at local pharmacies. Calamine lotion and oral antihistamines also can provide some relief. Other suggestions include cold packs, oatmeal baths, and compresses containing Burow’s solution (mixture of aluminum acetate and water), which is available over-the-counter at most pharmacies.
Approximately 10 to 15 percent of people will have reactions severe enough to require medical treatment, often in the form of oral or injected low-dose steroids administered by a doctor. Eating the plants can cause severe internal irritation, and inhaling particles of urushiol released by burning poison ivy, oak, or sumac can cause swelling of the respiratory passages, which can even result in death.
How to never have a serious poison ivy rash again
Patients should be properly educated on identification and avoidance of Virginia creeper to prevent future reexposure. When patients present with phytodermatitis, most health care providers immediately assume contact with Toxicodendron species due to its overwhelming prevalence. Knowing how to identify these poisonous plants can help you avoid an itchy experience.
Controlling infestations of poison ivy, poison oak, and poison sumac plants can be tricky because contact must be avoided. It may be tempting to burn a patch that intrudes in a backyard, but under no circumstances should you burn any part of these poisonous plants. Urushiol will become airborne in the smoke, and inhalation may cause severe swelling of the esophagus and respiratory passages, resulting in difficulty breathing and potentially death. The safest way to control these poisonous plants in your yard is by using an herbicide spray. Effective herbicides containing glyphosate and triclopyr, some specifically labelled for poison ivy control, can be found in the gardening section of most general stores. Follow instructions on the packaging label.
If it becomes necessary to cut the vines, keep in mind that severing the vines will release sap, and some urushiol may become airborne or drop from overhead leaves. The utmost care should be taken that no particles are inhaled. When cutting a vine, wear protective clothing (long sleeves, pants, and close-toed shoes), and a dust mask. Try not to sever these vines on a windy day, as this will increase the likelihood of allergens being spread. It is also best to do this in the winter, when sap is less abundant in the plant tissue. Avoid contact with these plants even if not allergic. Do not burn any part of these plants. Wash skin with soap and water or rubbing alcohol within 10 to 20 minutes if contact is suspected. Rinse thoroughly.
How to never have a serious poison ivy rash again
If you know you’ve been in contact with these plants, try to wash the exposed part of the body within ten minutes. Wash well! Use soap and scrub. If you still get the rash, try a product called Ivarest. If you do get it, try to think back and remember what you were wearing. Then wash those clothes! Remember, the oil lasts a long time! If you keep getting more poison ivy rashes, it must be on something you keep touching. If you have a dog or cat that goes outside, you can get the rash from touching your pet!
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