You can get poison ivy or oak a month later by putting on the same clothes without washing them. My favorite remedy for poison ivy is called Swedish Bitter Liquid, which you can find at natural food stores, and is designed to be a natural digest aid, but works beautifully to dry up poison ivy. Plantain, jewel weed, gum weed, are all good as well, but the Swedish Bitter Liquid is my favorite. Oatmeal poultice or baths are good for general itching ailments. Poison oak and ivy are closely related members of the same family, which includes cashews and mangos.
Some people are really sensitive to mangos.
They eat them and get a rash. If it's a simple ailment, even just looking something up in a book and trying it is fine, but if it's a serious condition, you might want the counsel of someone more experienced. There's no reason why you couldn't try Echinacea to fight off a cold, but if it's a serious condition like a kidney infection, you would want to consult with a professional. It's great to start learning and using. One of the best ways to learn is by your own experience.