“Leaves of three. Leave it be!” or some variant thereof has been an age-old memory device to avoid contact with poison ivy (Toxicodendron radicans). Problem is a lot of plants have three leaves all coming out from a common point. How do you tell them apart? Fortunately, poison ivy leaves have a unique characteristic. The stem (petiole) of the central leaf is noticeably longer than those of the two side leaves, as shown in this illustration.
Also, come July a single stalk appears bearing a number of tiny purple flowers, just to warn you it’s there. Those of us that react to poison ivy, and that’s 85% of the population, know well what happens if we come in contact with it. After 6 to 72 hours your skin itches like crazy. Then fluid filled blisters pop out on all the skin that contacted the plant’s oils. It looks like this:
We scratch and spread the oils. So-called satellite lesions start popping up. We’re miserable! The eruption can last a week or more.
So, what to do to prevent this and what to do if you don’t? Obviously, avoidance is the best course of action. Carefully dig up the plant if it pops up in your yard. Large patches might require an herbicide such as glyphosate (Roundup©). If you use an herbicide, be careful. Read and follow the instructions on the label. Wear protective clothing and face wear. If you are going out in the woods or other area where poison ivy might be found, wear long sleeved shirt and full-length pants. If you think your skin has contacted the plant, wash with a strong soap or detergent as soon as possible. If a rash appears, an over-the-counter hydrocortisone cream applied three to four times a day can help. An aloe vera cream can soothe the skin. The itching can be reduced by an oral antihistamine such as loratadine or fexofenadine. Your pharmacist can help point you to the right products. If you have an extensive rash, eye or face involvement, you’d best consult your physician.
Contributor: Jim Lakin, MD and Master Gardener Intern