Summer is a wonderful time to be out gardening and hiking. That is, unless you find yourself wrist- or knee-deep in a patch of poison ivy. It is not the leaves themselves that cause that horrible rash and itch but an oil on the leaves called uroshiol that adheres to your skin. Uroshiol is also on the stems, roots and berries.
The first step in preventing an exposure to poison ivy is knowing what it looks like so you can avoid it.
You may remember the saying “Leaves of three, let them be”. Poison ivy is green and appears as three leaves on a stem. The leaves take on a shiny look from the uroshiol oil as summer progresses. Then they turns reddish-yellow in late summer and fall.
Here is a photo: http://upload.wikimedia.org/wikipedia/commons/7/71/Toxicodendron_radican...
Poison Oak is poison ivy’s West Coast evil sister and causes an equally bad rash and itch. The leaves are still in groups of three, though sometimes it's groups of five, and there may be small whitish berries present. It can also grow like a vine.
Here is a photo: http://scitoys.com/botany/poison_oak_4_28_97_birdfarm.jpg
And our story would not be complete without some discussion of poison sumac, which contains the same oil as poison ivy and poison oak. There is a single leaf on the end of on a poison sumac stem with rows of paired leaves below it.
Here is a photo: http://0.tqn.com/d/landscaping/1/0/j/C/poison_sumac_leaf.jpg
Sometimes, despite your best efforts to avoid exposure to one of these shrubs, you do find you’ve had contact.
What should you do if you have been exposed?
The key is getting that tenacious oil off of your skin. This includes keeping any clothes that may have oil on them or tools you have been using away to prevent recontamination.
If you are fortunate enough to be near your home, or a place you can shower, or where there is running water, you have a good chance of washing the oil off.
You must wash the oil off your skin so the water runs away from your face.