What is urticaria?
Urticaria is the medical name for hives. Hives are itchy spots on the skin that appear suddenly, last minutes to hours, and disappear within a single day without leaving any mark. Hive are almost always raised but may be flat. Small hives are red or pink, round or oval, and warm to the touch. Larger hives may be white in the center surrounded by a ring of reddened skin. Large hives may be round or amorphous or amoeboid in shape.
What is angioedema?
The cells that cause hives are located at deeper levels in the lips, eyelids, hands and feet than in the rest of the skin. Hives in these areas result in swelling sometimes associated with a burning sensation. This special type of hive is called angioedema.
What is anaphylaxis?
Hives associated with a more serious reaction also involving breathing, digestion, or heart function is called anaphylaxis. Because anaphylaxis may cause suffocation or shock it can be life-threatening. Hives, though unpleasant, are not by themselves life-threatening.
Why do people get urticaria?
Urticaria results from the activation of mast cells. Mast cells are located throughout the body closely associated with small blood vessels and sensory nerve endings. When activated mast cells release a number of agents, primarily histamine, that trigger sensory nerves to register the sensation of itching, increase local blood flow resulting in heat and redness, and cause small blood vessels to leak plasma to produce localized swelling.
What causes urticaria?
Mast cells can be activated by a variety of mechanisms including allergies, infections, and even physical agents. Once mast cells release their chemicals the resulting symptoms are quite similar irrespective of cause. Food and drug allergies are common causes of acute urticaria. Physical agents include pressure, cold, heat, sunlight and even vibration.
What is the difference between acute and chronic urticaria?
Hives occurring everyday or nearly everyday for six or more weeks is called chronic urticaria. Chronic urticaria is rarely due to food or drug allergy. The most common cause is a mild autoimmune disorder directed against the mast cells. Other causes should be ruled out with appropriate laboratory tests.
How is urticaria treated?
Long-acting antihistamines are the most useful agents for treating hives. Taking antihistamines prophylactically is always more effective than taking it as needed because preventing the hives from starting is better than trying to make them go away once they've appeared. Other supplementary medications include H2 antagonists like Zantac and Pepcid, leukotriene receptor antagonists like Singulair, sympathomimetics like ephedrine and anti-inflammatory agents like prednisone. These medications may be added when antihistamines are insufficient to control hives.
Is urticaria curable?
When an allergic trigger can be identified hives are curable by avoidance. Chronic urticaria is subject to spontaneous remission but up to 50% of persons may have this disorder for many years.
