Of all the possible allergens, it may sound surprising to hear that there are individuals who are allergic to cold. When exposed to low temperatures, they may break into itchy welts that may either be localized or generalized. In medicine, this condition is referred to as cold urticaria. Mechanism of the allergic reaction In cold urticaria, cold temperature is the necessary stimulus to provoke an allergic response. When the body is exposed to cold air, cold water, or cold drinks, mast cells are activated to produce chemicals that trigger inflammatory responses resulting to the appearance of hives that may last for a few minutes up to days. The reaction varies for each person. But the exact pathophysiology on how cold sets off an immune response remains largely unknown. Cold urticaria may either be acquired or hereditary. Familial Cold Autoinflammatory Syndrome Hereditary cold urticaria is known as Familial Cold Autoinflammatory Syndrome. This condition is brought about by the mutations in certain genes responsible for regulating the process of inflammation. To be specific, the NLRP-3 sends out instruction for the creation of the protein, crypopyrin, while the NLRP-12 gene is in charge of monarch-1 protein. Both proteins work hand in hand to regulate the inflammatory process. Crypopyrin has a role in the activation inflammation, while Monarch-1 inhibits the inflammatory response. Therefore, any impairment of these genes leads to impaired inflammatory processes. FCAS usually presents with fever, rash, and arthralgia (joint pains) 9-48 hours following exposure to cold. The diagnosis of the condition is by evaluation of the symptoms. Gene analysis will provide pertinent data regarding mutations. Acquired Cold Urticaria In most cases, primary acquired cold urticaria is idiopathic or has an unknown cause. Others may have underlying hematologic problems, but are exceedingly rare. What your Doctor can do for you Cold urticaria can be diagnosed by performing an ice-cube test. In this procedure, an ice cubed will placed on top of the skin for 1-5 minutes. A wheal should form over the site, confirming the presence of cold urticaria. Once established, the person will be treated with antihistamines to manage the itching and rashes. The patient may have this condition for the rest of his life thus, avoidance of cold temperatures is strongly advised. What you can do Avoidance is the only preventive measure that a person with allergy to cold can do. Depending on the severity, the person may even be required to move to another place with a tropical climate. There shall always be an impending attack of anaphylaxis; hence, people with severe symptoms should always carry epinephrine and a Medic Alert bracelet.