|Classification and external resources|
Allergic urticaria on leg in the form of hives induced by cold.
|ICD-10||L50.2 (ILDS L50.210)|
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 7mm in diameter to as big as about 27mm diameter 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 (primary acquired cold urticaria). The acquired form is most likely to occur between ages 18–25.
Cold urticaria may be divided into the following types:
- Primary cold contact urticaria
- Secondary cold contact urticaria
- Reflex cold urticaria
- Familial cold urticaria
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.
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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). 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.
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.
Situations when reactions may occur 
- Cold weather: Exposure to cold or cool air for more than a few minutes can trigger a reaction. Avoid long walks outdoors during cold weather. Be prepared to bundle up and cover exposed skin as long as the weather remains cool. Experiment to find the right number of layers.
- Sweat: A reaction may even occur on a warm day when there is sweat on the skin. If there is a breeze it will rapidly cool the skin and create hives. Getting warm quickly by drying the skin and covering up will help to control the hives before they get too bad. Using or carrying a towel while exercising and wiping off sweat before it has a chance to dry is an effective means of preventing hives from occurring.
- Cold/Cool IV Lines: While in the hospital, inserting IV lines that have been refrigerated or are cool into individuals who are allergic to cold temperature can/may result in pain within the limb the IV is placed and a line of hives may appear within a radius of 6-8 inches from the IV site in the pattern of a line going up the limb. Notify your doctor/nurse of your condition so they will be able to use a machine which warms IV lines before they enter your body
- Swimming: Swimming can be especially dangerous as the rapid heart rate combined with the onset of hives can lead to hypotension. Taking an allergy medication before entering the water and conserving energy until your body adjusts to the temperature may help to prevent the hypotension. Take an antihistamine if you choose to go swimming; preferably a non-drowsy antihistamine, and have an individual with you at all times
- Air Conditioning: Entering a cool building during a summer day can result in an allergic reaction to exposed areas of skin, congestion from breathing the cool air and possibly feeling fatigued. Carrying jackets with you on warm days is a good idea in case you enter an air conditioned building.
- Cold Foods/Drinks: Eating or drinking cold or cool substances such as ice cream or even iced tea may result in the individuals tongue and surrounding tissues swelling. If eating cold foods or having cold drinks results in swelling of tissues in and around the mouth/throat it is advisable to take an antihistamine before consuming them and/or refraining from eating/drinking them.
- Cool/Cold Surfaces: Sitting on sidewalks which are cool, leaning on or grabbing a cold pole will result in hives forming on the area which had contact with the cool surfaces. The only treatment for these kinds of situations is trying to avoid cold surfaces, if you can not avoid them using gloves to touch them or using a pad to sit on cool sidewalks is helpful
- Restriction of Blood Flow: Typing or other activities which tense muscles and reduce blood flow can cool the body parts enough to cause itching and hives.
- Blood Flow: While putting hands or feet in hot water nails turn purple/white until the body gets used to the temperature.
See also 
- Cholinergic urticaria, a similar hives reaction in response to heat
- Goose bumps, an unrelated, normal response to cold temperatures
- Siebenhaar F, Weller K, : clinical picture and update on diagnosis and treatment (May 2007). Clin. Exp. Dermatol. 32 (3): 241–5. doi:10.1111/j.1365-2230.2007.02376.x. PMID 17355280 http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=0307-6938&date=2007&volume=32&issue=3&spage=241
|url=missing title (help).
- Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. pp. 267–8. ISBN 1-4160-2999-0.
- Mahmoudi M (May 2001). "Cold-induced urticaria". J Am Osteopath Assoc 101 (5 Suppl): S1–4. PMID 11409259.
- Magerl M, Schmolke J, Siebenhaar F, Zuberbier T, Metz M, Maurer M (December 2007). "Acquired cold urticaria symptoms can be safely prevented by ebastine". Allergy 62 (12): 1465–8. doi:10.1111/j.1398-9995.2007.01500.x. PMID 17900265.