University of Vermont Extension 
Department of Plant and Soil Science

Spring/Summer/Fall News Article

POISON IVY

 
Dr. Leonard Perry, Extension Professor
University of Vermont
 
 
Whether you garden, or just go hiking along country roads and in natural areas, you should be familiar with poison ivy.  Pets, and in particular dogs, that run in natural and overgrown areas also can bring the oil of this toxic plant back on their fur to share with you.  While animals aren’t sensitive to poison ivy, you may be one of the 85 percent of people that are allergic to this groundcover and vining plant, which you already may have discovered by accident.
          
“Leaflets three, let it be” is a phrase you may have heard, referring to the three leaflets of this common plant in eastern states (as well as the poison oak which is more common in the northwest and southeast states).  The leaflets of poison ivy which are up to several inches long, rather oblong and with pointed tips, shouldn’t be confused with the weedy box elder small maple tree (its leaflets have more pronounced indentations).  Nor should you confuse it with another common vine, the Virginia creeper, with five leaflets. 
           
Poison ivy can be an attractive vine, growing on the ground or up trees.  Early spring growth is reddish, fall growth can be various shades of yellow to orange. Rather inconspicuous greenish flowers in early summer lead to white, waxy berries in late summer.  It’s these berries that birds eat, spreading their seeds and so the plants.  Plants also spread by underground roots.

You should notice the woody stems as well, having aerial rootlets giving the overall appearance of a fuzzy rope.  Some gardeners, clearing out vines in the fall after leaves have fallen, end up tangling with this and its sap by mistake.            
When the plant surfaces are brushed against by person, animal or object, the toxic oil (urushiol, pronounced  you-ROO-she-all) is released.  This causes the usual skin rash that develops in a few hours to several days.  The rash may have streaks, the skin itches (but resist scratching), and rashes often swell creating watery blisters.  Although painful at first, rashes will go away in a few weeks with the pain and itching going away sooner.  Rashes spread only by the active oil from the plant, not from touching the rash or blisters and fluid they create. 

Some don’t get this rash the first time they’re exposed to poison ivy; others need a high concentration for symptoms to develop; a few are lucky and are immune.  Sensitivity varies with several factors—thicker skin (palms of hands) is less sensitive than thinner skin (faces); hairy or dark skin is less susceptible; a person sweating is more susceptible.  Children become susceptible by age 3, and are quite susceptible by age 12.
            
Obviously the best control is to avoid this plant. But if you do find you’ve brushed against it, wash the oil off with soap and water as soon as possible—ideally under 10 minutes after exposure.  Make sure to clean under fingernails. Cold water is best (it doesn’t open up skin pores as does hot water), and alkaline soap is said to break down the oil more effectively.

If just a small amount of oil is on the skin, and you’re not near a sink, use one of the several creams available from drugstores containing hydrocortisone.  (I like to carry a tube in my gardening tool kit for exposure to this and other plants such as stinging nettle.)  Other treatments for mild rashes include antihistamine pills, placing cool wet cloths on the infected skin, taking a cool shower, or taking a lukewarm bath with baking soda. Once you’ve washed up or treated the rash, wash all clothing (separately from others) and tools or objects that also may have touched the poison ivy.  The oil can remain on objects, and so cause problems, for many years.
 
If you’ve contacted much poison ivy without knowing, or are one of the few to develop severe symptoms, contact a doctor or poison control center immediately ( www.aapcc.org or
800-222-1222—a good number to have handy on the fridge or by your phone).  Severe symptoms include extensive rashes, rashes on the face or tender areas, fever, or signs the rash is becoming infected.  Prescription medicines are available for severe cases.  If you have problems breathing and swallowing, go to an emergency room at once. 
           
To get rid of this plant in landscapes, make sure to wear long sleeves and pants, gloves (heavy duty vinyl or nitrile, not cloth or rubber which the oil can penetrate), and even face protection.   If your dog has played among the ivy, use such gear too when giving the bath.  Pull roots from the soil or they’ll resprout.  Herbicides can be used, just make sure to get the correct ones and follow all label directions.  Above all, make sure not to burn poison ivy, or even wood and firewood that may have the vines attached.  The oil can be carried by the smoke, causing major eye and respiratory problems.
            
Photos to recognize poison ivy, as well as more tips, are available from the University of Connecticut IPM program (www.hort.uconn.edu/ipm).  Photos of this plant, its rashes, as well as photos of poison oak and poison sumac, can be found easily with a search at the American Academy of Dermatology website (www.aad.org/skin-conditions). 
 

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