Urticaria (Hives)

Urticaria, or hives, is a common skin condition that affects 15-25% of the population at some point in their lives. It affects females more often than males (4:1).  Most cases of urticaria are self-limited.

Wheals from urticaria can appear anywhere on the body, including the face, lips, tongue, throat, and ears. The pink or red wheals may vary in size from about 5 mm (0.2 inches) in diameter to the size of a dinner plate; they typically itch severely, sting, or burn, and often have a pale border.  The wheals usually fade within 24 hours, but new lesions may develop continuously.

Urticaria is classified as either acute or chronic.

Acute urticaria is defined as urticaria that has been present for less than 6 weeks.  This occurs most often in children and young adults.

Chronic urticaria is defined as urticaria that has been continuously or intermittently present for at least 6 weeks. When urticaria becomes chronic, it can be a very problematic and frustrating condition, both for the patient and for the clinician.  Ninety percent of chronic urticaria has no identifiable cause and is then to as chronic idiopathic urticaria (CIU).  This occurs most often in middle aged women.  Autoimmune disease such as rheumatologic conditions, hyper or hypo thyroidism, and malignancy should be ruled out.

The pathophysiology of urticaria is an inflammatory reaction in the skin, causing leakage of capillaries in the dermis, resulting in an edema which persists until the interstitial fluid is absorbed into the surrounding cells.

Urticaria is thought to be caused by the release of histamine and other mediators of inflammation (cytokines) from cells in the skin. This process can be the result of an allergic or non-allergic reaction, differing in the mechanism of histamine release.

Causes of acute urticaria are usually due to direct contact with an allergenic substance, an immune response to food or some other allergen, or for other reasons, such as emotional stress.  Drugs such as anti-diabetic sulphonylurea glimepiride, dextroamphetamine, aspirin, NSAID’s, penicillin, clotrimazole, sulfonamides, anticonvulsants, and herbal supplements have been implicated.  Other causes include recent or chronic infections, vaccines, or insect stings.  Even innocent events – mere rubbing, sweating, exposure to cold or sun can trigger urticaria.

Angioedema is a condition that involves swelling of the deep dermal and subcutaneous/submucosal tissues. It is often painful or burning and affects the hands, feet, eyes, lips, and sometimes airway.  Some patients can have both urticaria and angioedema, occurring simultaneously or separately. Approximately 50% of patients have both urticaria and angioedema, 40% have urticaria alone, and 10% have angioedema alone.  A severe case of angioedema of the throat can be fatal.

Treatment of urticaria can be very difficult. There are no guaranteed treatments or means of controls.  Some people are treatment resistant.  Medications can spontaneously lose effectiveness, requiring new medications to control attacks. It can be difficult to determine appropriate medications because urticaria is intermittent and outbreaks typically clear up without any treatment.

Most treatment plans for urticaria involve avoiding one’s triggers, but this can be difficult since there might not be any clear trigger. If triggers can be identified then outbreaks can be managed by limiting exposure to these situations.

There is a lot of exciting new research regarding urticaria and alternative treaments.  Your allergist can provide you with more information on the treatment options that are best for you.

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