| Cold urticaria | |
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| Classification and external resources | |
Allergic urticaria on leg in the form of hives induced by cold. |
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| ICD-10 | L50.2 (ILDS L50.210) |
| ICD-9 | 708.2 |
| OMIM | 120100 |
| DiseasesDB | 4688 |
Cold Urticaria (essentially meaning "cold hives") is an allergy where hives (urticaria) or large red welts form on the skin after exposure to a cold stimulus. The welts are usually itchy and often the hands and feet will become itchy and swollen as well. Hives vary in size from about the size of a pencil eraser (7 mm diam.) to as big as a fifty pence piece (27 mm diam.) or larger. The disease is classified as chronic when hives appear for longer than 6 weeks; they can last for life, though their course is often unpredictable. This disorder, or perhaps two disorders with the same clinical manifestations, can be inherited (familial cold urticaria) or acquired[1] (primary acquired cold urticaria). The acquired form is most likely to occur between ages 18–25.
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Cold urticaria may be divided into the following types:[2]
When the body is exposed to the cold, hives appear. 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 distinguishing it from a bruise or papule. Hives can last for a few minutes or a few days, and vary from person to person. Also a burning sensation occurs. During a severe reaction, hypotension, which can be life-threatening, can occur. A serious reaction is most likely to occur if the hives occur with less than 3 minutes of exposure (during a cold test).
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.
Diagnosis is typically obtained by an allergist or other licensed practitioner performing a cold test. During the cold test, a piece of ice is held against the forearm, typically for 2–3 minutes. A positive result is a specific looking mark of raised red hives. The hives may be the shape of the ice, or it may radiate from the contact area of the ice.
The most important treatment is to stay warm. Some air conditioned rooms and pools may be too cold for the skin. Warming up immediately after exposure to cold temperatures usually helps control the hives before they get worse. Although, the hives do not instantaneously disappear after warming the affected area(s), warming up afterwards reduces the time it takes for the hives to go away. Some patients report that spreading butter or vegetable shortening on their affected areas reduces the risk of future eruptions.
Allergy medications containing antihistamines such as Benadryl, Zyrtec, Claritin, Periactin and Allegra may be taken orally to prevent and relieve some of the hives (depending on the severity of the allergy).[3] There are also topical antihistamine creams which are used to help relieve hives in other conditions but there is not any documentation stating it will relieve hives induced by cold temperature. Please note however, it is not often that antihistamines work for cases like Cold Urticaria.
There has also been evidence to show that Cold Urticaria has been linked to a gluten intolerance, and gluten free diets have helped some CU sufferers.
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.
Contrary to popular belief, immersing the affected area in hot water or a warmer environment does not improve conditions. Immersing the affected area in warm water or a warmer environment is a means which is used to help bring the allergic reaction under control so it does not become worse.
The best treatment for this allergy is avoiding exposure to cold temperature.
Ebastine has been proposed as an approach to prevent acquired cold urticaria.[4]
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