Although not common, some people exhibit allergic reactions to some strange and hard-to-avoid things, like heat, cold, sunlight, sweat, and vibrations. Vibrations?
Treatments for these odd allergies include antihistamines, desensitization, and avoidance. Link -via Digg
Once again it is the body having a strange reaction to what should be ordinary stimuli, as histamines are released in response to the sufferer's body being treated like one of 007's martinis. Hives, weals and welts erupt after as little as five minutes exposure to any kind of vibration.
Treatments for these odd allergies include antihistamines, desensitization, and avoidance. Link -via Digg
And I also get hives if my skin gets too cold. It was hell in high school dressing out for PE for first period in the winter! I also would get them anywhere there was pressure on my skin like elastic bands on socks and panties and of course where you have pressure standing (my feet!) or sitting (my butt!). They went away for many, many years (18 years or so?) but have recently come back, but so far it's only happening with cold skin. What a pain in the ass allergies are. I think mine are related to an increase in soy, by the way.