In some individuals whose skin cells are very sensitive, they develop some red itchy lesions when exposure to cold. So this cold can be cold air or contact with cold surface or even contact with cold water. So what exactly causes this redness or the hives is the sensitivity. So there are cells which are cells are the mast cells which are very sensitive and what masks them sensitive is not known. So on exposure to cold what happens is this mast cells break open and they release some chemical substances called as histamine. This histamine causes vasodilation. That is dilatation and expansion of the blood vessels in the skin. So that is why you get the red itchy and bumpy lesions all over the skin. This occurs when it is a bit less severe. If the condition is more sever or if the person or more sensitive, then the person can also develop anaphylaxis, which can be life threatening. In that case what happens is swelling of the lips, tongue and the throat also. So thereby making breathing difficult and there might be loss of blood pressure and loss of consciousness. So if you have any of these symptoms like little bit of giddiness and light headedness after exposure to cold weather, you have to be careful and you have to consult a dermatologist. the treatment aspect of this condition is if you know you are sensitive and you know that you are about to get exposed to the cold weather or cold surface, then certain medicines called as antihistamines like fexofenadine and levocetrizine can be taken before hand. Once the reaction is already developed, then immediate iv hydrocortisone or other corticosteroids can be given and the best thing in this condition is to avoid the predisposing factors, that is avoid exposure to cold.