Thanks for your question. Cold urticaria is an uncommon form of urticaria or hives where the rash is triggered by a cold stimulus.
Cold urticaria is often idiopathic ie. the cause is unknown. However, in rare cases, this can be associated with underlying diseases including cryoglobulinaemia, infections and chronic lymphocytic leukaemia and some baseline screening blood tests may be need to be done to exclude these conditions.
Treatment is mainly using oral antihistamines. Sometimes, your doctor may advise you to updose the antihistamines for better control. In more resistant cases, other oral medications like leukotriene antagonists and cyclosporine may be required.
It is also important to avoid the trigger eg. jumping into a cold swimming pool may risk triggering extensive rashes.
In half the cases, the cold urticaria may disappear in 5 years. But in others,it may be persistent. Do seek further advice from your dermatologist who can advice you more on your condition.