Itchy skin rashes or hives may be caused by allergic or physical trigger. Hives, which may be confined to a local area of the skin or involve other parts of the skin, are usually associated with intense itching and/or burning sensation and may last for few hours, days, weeks or even months. At times, swelling reactions (termed angioedema in the medical jargon) involving various areas of the body may be associated and occasionally may lead to serious complications, such as breathing difficulties if the mouth or throat may be involved. Allergic triggers may be the cause of such hives and swelling reactions including food ingredients such as peanut, eggs, cow milk products and various drugs such as penicillin and codeine. Hives can also be caused by physical triggers such as pressure, persistent vibration, exposure to cold, heat, to sunlight or following exercise or hot showers. Swelling reactions or angioedema may not be necessarily the result of allergic triggers but rather a manifestation of genetic predisposition that must be identified, such as in the case of Hereditaruy Angioedema (HAE).

Other non allergic triggers are food additives such as food preservatives. Occasionally, hives may be associated with certain vascular diseases and require a thorough clinical evaluation. In most cases however, the exact cause is unknown, yet hives are relatively easy to control. Treatment of hives may include avoidance of the offending agent(s) when identified, antihistamines and occasionally anti-inflammatory agents such as steroids. In the event of swelling reactions due to genetic such as in Hereditary Angioedema, it is crucial to identify the genetic cause since very innovative and effective treatments exist today which can be life saving.