Poison Ivy: Toxicodendron radicans
Leaves in three? Let them be!
Have you ever heard the phrase "Leaves in three? Let them be!"? This is because poison ivy has three leaves per leaflet, and it's an easy way to remember what to stay away from. A rash from poison ivy, poison oak or poison sumac is caused by an oil found in these plants called urushiol (you-ROO-shee-all). When this oil touches your skin, it often causes an itchy, blistering rash. Another easy way to identify poison ivy during this time of year is by it's change in colour. Because of the change in temperature the leaves can turn from green, to yellow, to orange, to red, before falling off for the winter.
What if you come in contact with the plant?
When you come in contact with poison ivy, it has an oil on it that makes some people react and develop a rash. But the oil doesn't stay with the rash; so brushing up against someones rash by accident doesn't necessarily mean you yourself are going to contact the poison icy rash. Some studies have shown that 85% of people are allergic to poison ivy, but this could explain why some people don't seem to be affected by poison ivy at all. It can take several days or even a couple of weeks for a rash to form, and the time of development for a rash differs for each person.
You should avoid poison ivy growing in the wild because it can cause an itchy, annoying, and even painful rash. If you do come in contact with the plant, it's best to thoroughly wash your skin to remove any oils and also wash your clothes. The oil can stay on clothes and be contagious that way. Cold compresses and antihistamine pills can also be used to help suppress the pain, and urge to itch.