Hives result from dilation of capillaries which allow fluid to flow out into the surrounding tissue which is the epidermis. They resolve when the body absorbs this fluid. The border of a hive is described as polycyclic, or made up of many circles, and changes as fluid leaks out and then is absorbed. Pressing on a hive causes the skin to blanch (turn pale as blood flow is interrupted), distinguishing it from a bruise or papule. Hives may appear immediately or after a delay. Hives can last for a few minutes or a few days, and vary from person to person. Also, a burning sensation occurs. A serious reaction is most likely to occur for patients where the hives occur with less than 3 minutes of exposure (during a cold test). Cause
The hives are a histamine reaction in response to cold stimuli, including a drastic drop in temperature, cold air, and cold water. There are many causes for cold hives, most are idiopathic (meaning they have no known cause). Some rare conditions can cause cold hives, and it can be useful to test for these conditions if the cold hives are in any way unusual. Scientists from the USA National Institutes of Health have identified a genetic mutation in three unrelated families that causes a rare immune disorder characterized by excessive and impaired immune function: immune deficiency, autoimmunity, inflammatory skin disorders and cold-induced hives (cold urticaria). "The mutation discovered occurs in a gene for phospholipase C-gamma2 (PLCG2), an enzyme involved in the activation of immune cells.
If standard dosing is ineffective, increasing dosages up to fourfold is recommended to control symptoms.The second-generation H1-antihistamine rupatadine was found to significantly reduce the development of chronic cold urticaria symptom without an increase in adverse effects at doses of 200 mg and 40 mg.Allergy medications containing antihistamines such as diphenhydramine (Benadryl), cetirizine (Zyrtec), loratadine (Claritin), cyproheptadine (Periactin), and fexofenadine (Allegra) may be taken orally to prevent and relieve some of the hives. For those who have severe anaphylactic reactions, a prescribed medicine such as doxepin, taken daily, should help to prevent and/or lessen the likelihood of a reaction and thus, anaphylaxis. The effectiveness of topical antihistamine creams against hives induced by cold temperature has not been evaluated.Cold hives can result in a potentially serious or even fatal systemic reaction (anaphylactic shock). People with cold hives may have to carry an injectable form of epinephrine (like Epi-pen or Twinject) for use in the event of a serious reaction.Studies have found that omalizumab (Xolair) may be an effective and safe treatment for cold urticaria in patients who do not sufficiently respond to standard treatments.Ebastine has been proposed as an approach to prevent acquired cold urticaria. See also
Amyloidosis
Cholinergic urticaria, a similar hives reaction in response to heat
Aquagenic urticaria
Diascopy
Erythema
Goose bumps, an unrelated, normal response to cold temperatures
List of cutaneous conditions
Skin lesion
Plaid syndrome

References


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