Most allergies are to physical items, but there are a handful that are reactions to environmental conditions, including cold. Those who suffer from this strange ailment must combat the cold in ways that would make most hardy northerners laugh as they wander around in shorts and a T-shirt while they shovel the snow from the driveway. Any exposed skin will break out in hives, and during the depths of winter an acute attack is a constant risk. For most who suffer from this particular allergy, swimming is extremely dangerous as it lowers the entire body’s temperature to the point that it brings on anaphylaxis. Though rarely fatal, it does have the benefit of ensuring you’ll have a medical reason to never, ever be talked into going polar bear swimming. Who knows, you might even get prescribed a tropical vacation every winter.