Poison ivy is short for a rash from poison ivy, as well as just the name of the plant that causes the rash. The rash is an allergic reaction to the oil urushiol which is found in the leaves and stem of the poison ivy plant as well as poison oak, poison sumac, and other more unusual sources like the shell of the cashew nut. The allergic reaction is an autoimmune response.
Not everyone has the strong allergic reaction. But some people that were immune develop an allergy after repeated exposure. And there are claims that immunity can be developed temporarily from repeated ingestion of the leaves. That is not a claim I am ready to test for myself.
“Leaves of three let them be.” is the adage that tells us what poison ivy looks like. However, there are examples of poison ivy that aren’t so easy to identify. And the dead stems can still provoke the rash.
Don’t burn poison ivy, since there is the possibility of spreading the oil through the air if the fire is not hot enough. Breathing this smoke can cause a systemic reaction.
If you want to get rid of the plant, I have had the best luck with cutting the vine near the base, and spraying the leaves with an herbicide like Roundup. Wear long sleeve shirt and long pants, and be sure to wash your clothes and take a shower when you are done. Wear vinyl gloves but not rubber gloves. A barrier lotion of Ivy Block has been FDA approved for the prevention of poison ivy rash. If you do know that you have skin contact with poison ivy, soap and water washing within 10 minutes will increase the chances of avoiding all rash. There is some fear that soap and water may actually help spread the oil, and that rubbing alcohol should be used to clean before you use the soap. Tecnu treatment before there is a rash can reduce the severity, or even prevent the rash. A cold shower may be preferable to using hot water because the hot may increase absorption of the oil.
For large areas of poison ivy growing, a fun solution is goats have been used to destroy the plant since they don’t have a problem eating poison ivy, and are pretty voracious eaters. There are some businesses that will rent goats out for clearing brush. But any farmer may be willing to rent you goats if you have the ability to fence them in, and will supplement the goats diet with a nutritious feed.
If you do get poison ivy, make sure to clean all your dirty clothes, sheets, and towels. You can’t spread poison ivy from scratching the rash, but it sometimes seems like you can since the oil is invisible and may not have been cleaned from shoes and other forgotten surfaces. Also, the allergic reaction can be slow to develop in some areas, so parts of your skin that you thought were clear may develop a rash a couple of weeks later. Bad cases of the rash are sometimes considered systemic, and the rash may appear where there has been no oil contact. A doctor may prescribe an antihistamine or Prednisone. If you need Prednisone, make sure the prescription will last you while tapering off for at least a full two weeks.
One of the reasons it can take so long for the rash to clear up, is the oil is still there in the skin causing the allergic reaction. The product Zanfel is expensive, but it can quickly stop the itching, and bind to the oil to stop the allergic reaction. If you search for “compare to Zanfel” you will find at least one less expensive generic version of Zanfel called Walgreens Poison Ivy Wash. You may need to make repeated applications of Zanfel for lasting relief.