I’ve been using an HerbPharm formula for years that I swear by – it used to be called Grindelia Sassafras but they renamed it in the last year or so to Poison Oak Remedy or something like that -it’s one of the few that has a spray top. I attribute the success of this formula in terms of stopping the itch largely to the potent menthol also in there, though I suspect that the Grindelia and Sassafras may help in healing the rash and irritated skin. I’ve found that after a very hot shower to open pores, spraying this stuff brings great relief and zero itching for 6-8 hours. I always thought it would be fun to make my own but have not found the grindelia yet (in the wild) or have specific feedback on methods. good luck in your research!