Stay Clear of Leaves of Three — Preventing Poison Ivy This Summer


"Leaves of three, let them be. Hairy vine, no friend of mine." One of the more useful things my mother ever taught me was how to recognize poison ivy plants. Take a moment to teach your family today; it can come in very handy!

There are two kinds of dangers with poisonous leaves in Massachusetts: poison ivy and poison sumac. We have no poison oak in this part of the northeast, so let's focus on the other two. Poison ivy has green leaves grouped in three, with the classic notched edge on the outside of the back two leaves and sometimes notching on the middle leaf. It turns reddish in the fall, and the hairy climbing vines on trees are dangerous, even in the winter. Poison sumac is a small tree that usually lives in the wetlands, and has 7-13 smooth leaflets arranged opposite to each other with a red branch. You can review pictures online to make sure you can recognize each. 

Removing poisonous plants

To remove the plants from your yard, it is recommended to spray Roundup on individual plants. It may be dangerous or ineffective to try pulling up several plants yourself. Professional poison ivy removal companies are available if needed.

How poisonous plants result in allergic reactions

Poisonous plants make an oil called urushiol that takes anywhere from five minutes to two hours to bind to your skin. Once it binds, our body has an allergic response to this and it causes a rash. This can take about four hours to four days to occur. The rash is a red itchy rash with tiny blisters in patches and lines. About 70 percent of the population is allergic to usushiol oil, 15 percent have severe breakouts, and a lucky 30 percent (myself included) never react at all. You can pick up this oil from tainted clothing, shoes, pets, garden tools, or even smoke from burning the plant.

You cannot spread the rash to another part of your body by simply touching the rash and then touching another part of your body or someone else’s skin. This is a common misconception. Our body’s allergic response, which can last from 3-21 days, will occur in the areas of the skin that bounded to the plant oils. The rash may show up in various places over time and it may appear that the rash is spreading. The timing of when the rash can appear is related to the amount of oil exposed to the skin and the thickness of the skin.

What to do if you are exposed: Scrub with soap and water!

If you think you have been exposed to poison ivy, the oils can be washed off and you are no longer in danger of the oils touching other parts of the body. You must wash yourself and all your garments quickly. The sooner you wash, the more oil you can get off without it binding to the skin. Special preparations are not needed, just a strong scrubbing with soap and water. Rubbing alcohol, Tecnu, and Zanfel are commercial products that do help removal. The oil is easily spread from one body part to another, especially under one's fingernails, so clean all parts of your hands vigorously after exposure. Don’t forget to clean off garden tools, clothing and other items that may have the plant oils on them.

At home, you can apply calamine lotion to provide symptomatic relief. Dry up lesions with astringents like Domeboro or Burow's solution to heal lesions faster. Take oral antihistamines like Benadryl to help with the itching, especially at night. A mild steroid cream, such as Cortisone 10, may help, or your doctor can prescribe you a stronger steroid cream or a systemic steroid, like prednisone, to quiet down your body’s allergic response. There is no evidence to show that any solution can remove the oil from the skin once it has already bound.

Learn to recognize the plants and be aware of your surroundings while outside. By doing so you can save yourself weeks of misery! These actions can help prepare you for poison ivy and poison sumac this summer. Our clinicians are available for any questions or consultations about medical issues.

This information was provided by Dr. Linda Kintz, a board-certified family practice physician with Emerson Urgent Care at Hudson, located at 38 Highland Commons East in Hudson, near Market Basket. More information can be found at