Is Poison Ivy Really Poisonous?

By Howard J. Bennett

Going camping and hiking in the woods are two of the high points of being a kid. The trouble is, there’s more to a forest outing than sleeping under the stars and throwing burrs at your friends. Some things in the woods are dangerous. And while few people will have the misfortune of running into a mother bear with her cubs (this is very dangerous), most of us will cross paths with poison ivy at one time or another.

Poison ivy isn’t poisonous in the true sense of the word. However, most people are allergic to a chemical named urushiol (oo-ROO-she-al) that is produced by the plant. It’s probably called “poison” ivy because the plant can cause a nasty rash and people used to think it was poisonous.

If you come in contact with urushiol, it will bind to your skin within 30 minutes, meaning it can no longer be spread or washed off. But it can be spread during this 30-minute period, which is why you can get the chemical on your legs and end up with a rash on other parts of your body.

A few days after you touch the plant, your skin will start to itch and red streaks (and blisters) may pop up in various locations. The reason the rash spreads over a few days is because the places that were exposed to more urushiol break out sooner, NOT because scratching causes the rash to spread. Therefore while constant scratching isn’t good for your skin, it won’t result in your being covered from head to toe with icky, disgusting blisters. This also means that you can’t “catch” poison ivy from a friend just because you touch him or his rash brushes up against your skin.

Poison ivy does not bind to clothes or hair, so you can theoretically spread the rash days later by touching unwashed clothes after you’ve had contact with the plant. So do as your mom says—take a shower when you come home at the end of the day and put your dirty clothes in the laundry hamper instead of tossing them on the floor.

Mild cases of poison ivy can be treated with oatmeal baths and/or creams that can be bought without a prescription. If the rash is extremely itchy or has spread to large parts of your body, you may need stronger creams or even oral medication that your doctor can prescribe. Poison ivy can get infected, so if you develop red, swollen areas that hurt, your parents should take you to the doctor.


© 2012 Howard J. Bennett. All Rights Reserved.
(First published in the Washington Post 9/21/09.)

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