Your doctor will need to ask numerous questions in an attempt to find the possible cause. Since there are no specific tests to determine the cause of hives, testing will vary depending on one's medical history and findings on clinical examination by the doctor. Certain people can develop hives from sunlight, cold, pressure, vibration or exercise. Hives due to sunlight are called Solar Urticaria. Reaction to the cold is more common.
Hives appear when the skin is warmed after exposure to cold.
If the exposure to cold is over large areas of the body, large amounts of histamine may be released which can produce wheezing, flushing, generalised hives and fainting. Cholinergic urticaria is tiny bumps surrounded by a white or red halo which come on with exercise, heat or emotion. These bumps itch intensely. Anything which raises the skin temperature can cause these tiny hives - sweating, sunlight, hot baths, blushing or anger. The most common of the physical urticarias is called Dermatographism .