The best prevention for poison ivy or poison oak rash is to avoid touching the plant and getting its toxic oil on your skin. But it can be impossible to avoid at times, or you may fail to
identify it until it is too late. You can prevent poison ivy rash or poison oak rash by using Ivy Block (see below), or by swift removal of the toxic oil as soon as possible. The FDA recommends applying rubbing alcohol to the exposed area, rinsing with warm water, then washing with soap and water. Products have been developed to help make that process more effective and more convenient.

Photo © Wendy BumgardnerIvy Block Lotion is meant to be used before you are exposed to poison ivy or poison oak. If you know you will be walking in an area infested with poison plants, it is smart to coat any exposed skin with this lotion. The lotion will prevent the toxic oil from adhering to your skin and setting off the reaction that produces the rash.
The FDA recommends immediately wiping the area of contact with alcohol to remove the toxic oil. Bringing individually packaged alcohol prep pads lets you do that conveniently. I generally carry these on longer walks as part of a
blister kit. You need the alcohol, so don't make the mistake of buying alcohol-free wipes.
This is an item you should be carrying along on your walk to use in restrooms that lack soap and water. Hand sanitizer is primarily alcohol, and you should apply alcohol as soon as possible to an area exposed to poison ivy or poison oak. Using hand sanitizer and a tissue is an easy solution.

Photo © Wendy BumgardnerTecnu is the pioneer in poison ivy and poison oak scrubs. This preparation is an actual scrub that contains grit to help you remove the toxic oil from the skin. Once the oil is off the skin, the reaction to it stops and healing can start. You can use this scrub anytime after exposure, including after the rash has developed. The sooner, the better.

Photo © Wendy BumgardnerHard-milled lye soap is the traditional scrub for after exposure to poison ivy or poison oak. All Terrain produces just such a bar, labeled for the this use. It even includes a bag to save the soap in for future use. The soap lathers well, enabling it to strip all oils off the skin to get the toxic oil. But this also dries out your skin, so the package includes moisturizers to help replace your own skin oil.

Photo © Wendy BumgardnerThis is the original skin cleanser from Tecnu, and you can also use it on gear and clothing. They recommend washing skin within two hours of exposure, so it would be wise to keep this handy with your walking gear. But you can use it at any time after exposure to minimize the eventual rash. You can use it once the rash has appeared and it will help the rash stop bubbling and start healing. The key is removing the toxic oil from the skin whenever you can.

Photo © Wendy BumgardnerFels Naptha soap is a traditional scrub for the removal of poison ivy/oak oil from skin, clothing, and gear. As with other scrubs, it should be used as soon as possible after exposure to prevent the rash. But it can also be used after the rash develops to remove remaining oil and shorten the rash outbreak. You can treat clothing and gear that has been exposed with the soap. For clothing, dampen the cloth and rub on the soap as a pre-treatment before washing.
"Outsmarting Poison Ivy and Its Cousins." FDA Consumer, September, 1996.