Actually, my brother does. He was a soldier stationed in Kosovo years ago and came down with a terrible facial rash. It got so bad there was talk of sending him back to the states because they didn't know what it was. Turns out, it was an allergy to Mango. I'm not sure if he eats mango anything now....personally, if I had an allergy to a certain food I'd just avoid it. Mine happens to be mushrooms, so I take no chances and never eat them.

Mango skin contains urushiol, the active ingredient of poison ivy. Just in much smaller quantities. You must be sensitive to it, I do break into rashes with PI, but nothing from the mango, even when living in Brazil and eating lots of ataulfos.

My question is whether or not cooking or drying the mango breaks down the oil..

It is only in the skin. Peel it thickly.

If it's a reaction to urushiol, then cooking or drying will not help. It's a very tough chemical and is very stable(poison ivy oils can stay active on tools for years). I'm fairly allergic to PI, but luckily mangoes don't bother me. You may be hypersensitive to urushiol.

If it's a normal food allergy than cooking/drying may work, cooking would probably be more effective of the two. I have a friend who's allergic to uncooked peaches/pears/apples but not cooked.

Since you can drink juice(probably pasteurized) it's possible you could have an allergy to raw mango. You could always try a test with a small amount of cooked mango that you've prepared. That way all other variables would be the same, as opposed to manufactured products like juice/salsa. If you're hypersensitive to urushiol then you'll probably just have to stay away unfortunately.

Here is a link that might be useful: Wiki on raw fruit allergies that might be helpful.