If you rub yourself with poison ivy, blisters will form almost instantly. So, what would happen if you ate a poison ivy salad? Well, the leaves would blister your mouth and throat as you swallow. And as your tissues swell, it could block your airways, making it hard to breathe. When it reaches your stomach, you'll have severe pain and vomiting. And it could even give you terrible diarrhea. Just make sure you don't use the leaves to wipe.