Why Does Poison Ivy Cause Itchiness?
The itchy rash which results from touching poison ivy is caused by oil that is found in all parts of the plant. It’s called urushiol, colorless, odorless oil (called resin) contained in the leaves of the plants. After the oil touches the skin, itching and reddening develop, and blisters may form. It’s itchy, too.
After a few days, the blisters may become crusty and start to flake off. It takes 1 to 2 weeks to heal. Urushiol is considered an allergen because it causes an allergic reaction — the rash and sometimes swelling. Not everyone will get a reaction, but about 60% to 80% of people will. This reaction can appear within hours of touching the plant or as late as 5 days later.
Sometimes this oil can be washed away with soap and water before it penetrates the skin and does its damage. Poison ivy can grow as a bush, or as a vine that climbs up trunks of trees. It can be recognized by its groups of three leaflets on a single stem. Poison ivy leaves are shiny and green in the summer and turn red and orange in the fall.
These plants can be anywhere — from the woods to your own backyard. The green leaves of poison plants blend right in with other plants and brush, so it’s possible to sit down in a patch of poison ivy and not even notice.
You might notice later, of course, when you start to itch! And it’s not enough just to know what one kind of poison ivy looks like. Poison ivy comes in several types — and may look different depending on the time of year.