Why didn’t anyone know this when I was a kid?
Poison ivy rashes don’t occur immediately. It takes a few hours. That’s the key to avoiding the rash: if you can get the urushiol (the stuff that makes you itch) off in time––within two to eight hours––you will not get a rash. The catch is that urushiol is really sticky, like axle grease. Using dish soap and a washcloth and scrubbing should do the trick.
H/T to HolyKaw