Causes of Hives Classic urticaria, commonly known as hives, is a transient skin disorder in which lesions are elevated with well-circumscribed margin of redness and swelling. These skin lesions are called wheals. Wheals vary in shapes from round to oval, and are often itchy. The lesions and itchiness of hives is caused by an immunologic response of your body, primarily due to the action of histamine release. Hives is generally caused by a lot of allergic conditions or diseases. It can either be acute or chronic, wherein the former persists for less than 6 weeks and the latter persists for at least 6 weeks.

Allergies Food, drugs, insect bites, and contact to some substances cause hives due to allergic reaction. This is due to hypersensitive reaction of the body. In food allergies, the body reacts to the food protein. For some people, this food protein is recognized by the immune system of the body as a dangerous foreign substance. This recognition will cause histamine release that produces the allergic reaction symptoms. Eggs, peanuts, and sea foods are some of the most common known foods that cause allergic reaction symptoms. In children, food allergy is one of the major considerations in acute urticaria.

The same thing happens in the immune system of the body when an individual is having an allergic reaction to drugs, insect bites, and substance contact. Any drug can cause an allergic reaction but the most common has been noted on antibiotics intake. Insect bites such as bee and wasp stings cause a release of its venom in the body. Some individuals are sensitive enough to have an allergic reaction due to this. Also, there are some individuals that have allergic reaction when their skin has had a contact with a substance. It is also important to take note that non-allergic reaction can also cause hives by the above examples.

Hives Due to a Medical Condition Some infections, hormonal, endocrine and autoimmune diseases cause hives. These include hepatitis B and C infections, excessive or deficiency of thyroid hormone production, systemic lupus erythematosus and rheumatoid arthritis. Hives Due to Physical Causes Physical causes include pressure, sunlight, cold, and cholinergic urticaria. Individuals with dermographism display hives on areas subjected to light pressure or scratching of skin. Exposure to sunlight can produce hives within minutes and is common in individuals with a systemic disease called erythropoietic protoporhyria.

Exposed areas of the body to cold are usually affected with hives in individuals with abnormality in their circulating body proteins. Cholinergic urticaria is triggered by heat, emotional stress, or exercise. Other physical causes of hives are vibration and water. Unknown Cause Hives due to an unknown cause is called idiopathic urticaria. The cause is unknown because it cannot be specifically identified by the individual’s history of symptoms, physical examination findings, and laboratory work ups. Idiopathic urticaria commonly presents in chronic form.

Chronic idiopathic urticaria is present in 80 to 90 percent of individuals, and these individuals may have associated physical causes (such as pressure and cold) of urticaria. References Fauci, AS. , Braunwald, E. , Kasper DL. , Hauser, SL. , Longo, DL. , Jameson, JL.. , and Loscalzo, J. (2008). Harrison’s principles of internal medicine. 17th ed. USA: The McGraw-Hill Companies, Inc. Food allergy (2010). Retrieved 27 November 2010 from http://www. emedicinehealth. com/script/main/art. asp? articlekey=59365&pf=3&page=2 Urticaria. (2010). Retrieved 27 November 2010 from http://emedicine. medscape. com/article/137362-print