My GP had no answers, but figured that an antihistamine couldn’t hurt. The allergist that I saw was able to rule out any other environmental and dietary issues that might be contributing to the hives, but could find no cause. She did determine that I was allergic to dust mites, but my issues with an indoor allergen that gets worse during the winter did nothing to explain why my problems started when I stepped outside. I was ready to write it off and learn to live indoors until an osteopath who worked at my gym told me about something called cold urticaria. Armed with this new information, I marched back to my GP’s office to demand confirmation that this was what was going on with me. And yep, after some research, he finally agreed.