Urticaria, commonly known as hives, nettle rash or uredo, is a form of an allergic reaction. Chronic urticaria can continue for 6 weeks or more and it is estimated to affect 1 in 1,000 people.
Urticaria presents as raised skin welts that can be 5 mm (0.2 inches) in diameter or more, itch severely, and often have a pale border. It usually starts as a smaller itchy patch of skin that grows and turns into red welts that are swollen. The itching may become severe and may be exacerbated by alcohol consumption, exercise, and emotional stress. In many cases, the center of the red hive will turn white when pressed (known as “blanching”).
What causes it?
Urticaria is generally caused by direct contact with an allergenic substance or an immune response to food or some other allergen. It can be triggered by food allergies (such as peanuts, eggs, nuts, and shellfish), medications, insect bites or stings, allergic reactions to latex, pet dander, pollen and some plants like poison ivy or oak. Some people develop urticaria simply by touching certain irritants.
If you are experiencing hives, your dermatologist may recommend antihistamines to block the allergic reaction, or a corticosteroid or immune modulator to ease the symptoms. If the cause of the irritation can be identified, the best treatment is to eliminate it.