Hives are itchy, raised, red welts that develop on the surface of the skin. Also known as urticaria, they occasionally present alongside angioedema. Ranging from a few millimeters to several centimeters, hives usually fade once the cause of the breakout has been addressed. Unlike angioedema, hives on their own aren't a symptom of an allergic reaction. But, when they occur with swelling, allergies are the most common cause. Generally, hives last for less than six weeks.

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