Yes. Occasionally, people who have reacted to poison oak will begin to have allergic reactions to fruits in the same plant family. Poison oak, poison ivy, mango, cashew, and pistachio all belong to the plant family "anacardiaceae". A reaction to poison oak can lead to future reactions to mangoes. So, it is best to avoid poison oak and poison ivy, even if one has never suffered a reaction previously.
No. No - poison ivy causes only local contact irritation and will not cause long term issues or problems. Poison ivy causes trouble by contacting the plants sap - and its not contagious. However, people can continue to come in contact with it if you don't eradicate the plant.
Yes. You'll have long term caution about going through greenery without long sleeves on, but that's pretty much it. Also, each poison ivy exposure tends to produce progressively nastier rash, but each rash will, eventually, go away, unless they get infected, in which case they can scar or cause serious illness.
Itchy rash. Typically one gets a very itchy blistering rash in the areas which contacted the poison ivy. But one can even transfer the oils to other parts of the body if not careful. Scratching makes things worse so don't do it! Some people don't react; they're very lucky! And if you wash the oils off quickly (within 15 minutes), you may not react. Use cool water and good gentle soap.
Poison ivy. Signs and symptoms of a poison ivy rash include: redness, itching, swelling, blisters, often, the rash looks like a straight line because of the way the plant brushes against the skin. But if you come into contact with a piece of clothing or pet fur that has urushiol on it, the rash may be more spread out.