Poison Ivy
A plant (fig. 1) that can cause an allergic reaction after contact.
What is it?
Just the 
mere mention of poison ivy can make the skin tingle. Contact with this mighty plant causes a red and itchy rash in 85% of the population, and at least 10 million people will have an allergic reaction to the plant this year alone.
An oily substance inside the plant called urushiol (yu-ru-she-ol) is what actually causes the rash. Stepping on poison ivy or somehow breaking the leaves releases the oil that soaks into your skin and produces an allergic reaction. The rash usually appears within 12 to 48 hours after contact.
A lucky 15% of the population is immune to the ivy and does not experience an allergic reaction. But, it is more likely that subsequent exposures to the plant will wear down your resistance and trigger a future reaction.
Poison ivy can grow in your backyard, as well as in wooded areas. Picking up exposed objects, such as a ball, can cause a rash since the oil easily sticks to things. A pet could even rub against the plant and spread the oil around your house. And the really bad news? The oil can remain potent for a year or longer.
How do I know I have it?
A red, itchy rash will eventually produce blisters that break open, crust, and soon heal.
With a severe reaction you may have a fever, headache, swelling (body, throat, eyes), or a general feeling of discomfort. If you experience any of these symptoms, see your health-care provider immediately.
Typically, the rash will first appear on your face and then on other commonly exposed parts of the body, such as the arms and legs. But any part of your body can be affected if it has come in contact with the urushiol.
The rash rarely appears on the scalp, the palms of your hands, or the soles of your feet. This is because the skin in those areas is thicker and the oil cannot be absorbed so easily.
Your health-care provider can tell if you have poison ivy by inspecting your body for a rash and by discussing possible exposures to the plant.
How can I treat it?
Over-the-counter ointments can help with mild reactions, such as calamine lotion, which relieves itching. Keep in mind that there is no cure for an allergic reaction to poison ivy, but you can treat the symptoms to make yourself more comfortable until the condition runs its course, which usually takes 14 days.
Indulge in lukewarm baths with epsom salts, baking soda, or an oatmeal solution. Afterward, dab on some calamine lotion to dry up the blisters. Cover the infected area with a sterile gauze. Cool cloths on the affected areas can be very soothing. If you are having difficulty tolerating the itching, as most people do, you can take an oral antihistamine, such as Benadryl. Do not, however, use a topical antihistamine because it can actually worsen your condition.
Immediately see your health-care provider or dermatologist if you have a severe reaction, including: swelling; facial-or genital-area rashes; fever; extreme redness or pus; a widespread outbreak (covering 20% of the body or more). An oral medication such as prednisone may be prescribed to stop the reaction. Treatment must start within several hours to be effective, so if you’ve had a severe reaction in the past, see your health-care provider without delay.
Avoid scratching if you can. Although scratching will not spread the rash, it can cause complications such as an infection or even nerve damage.
How can I prevent it?
Know what the plant looks like. The old saying, "Leaves of three, let them be," is a good start because poison ivy usually has three leaves. Unfortunately, identifying poison ivy is not as easy as counting to three.
In the winter the plant has greenish-white berries, but no leaves. When the plant does have leaves they are oval, with smooth or toothed edges. In the summer the leaves are green; in the spring they are red; and in the early fall they can be yellow, red, or bronze. The plants may also have small flowers that vary in color from cream to yellow-green. If you see leaves with black spots, this is a sign that urushiol is on the plant, so stay away!
When you are outdoors, wear long sleeves, long pants, socks, and shoes. Two products on the market, IvyBlock and StokoGard, can prevent the rash when applied to the skin 15 minutes before exposure.
If you do happen to come in contact with poison ivy, you can avoid a painful allergic reaction by taking these steps:
- Immediately rinse the area with water. If you are away from a sink, water from a stream, lake, or garden hose will do.
- Next, pour rubbing alcohol over the skin. Do not use pads or rub the skin as this can spread the urushiol to other areas.
- As soon as possible, remove and wash all clothing in a washing machine with soap, being careful not to re-expose yourself to the urushiol. Also, wash any garden tools, pets (pets are not allergic to urushiol), or other objects that may have come in contact with the plant.
Frequently asked questions
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Where can I find more information?
- US Food and Drug Administration
www.fda.gov - Poison Ivy, Oak and Sumac Information Center
poisonivy.aesir.com - Kingdom: Plantae
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