I often break out in hives (allergic reaction) when sweating in cold weather. what is this condition? should i be concerned? how do you treat?

Cold urticaria: This is a relatively uncommon condition triggered when cold temperature causes capillaries near the skin surface to release fluid into the underlying skin creating the raised hives. It can be inherited or acquired. Treatment includes use of antihistamine products and the avoidance of cold. Simple cold urticaria may come and go over a 6 week period while some will have it chronically.

Cold urticaria: Cold urticaria is an allergy to cold temperatures. Exposure to cold air or water causes redness, itching, swelling and hives on the skin that has been in contact with the cold. As much as possible, people with cold urticaria should avoid exposure to cold air and cold water. Treatment may include antihistamines taken before cold exposure. Consult your doctor.