And they can grow in size from that of a mosquito bite to a saucer or larger. They tend to occur in batches and last anywhere from a few minutes to several days. Hives can be, but aren't always, an allergic response to something you touched, inhaled or swallowed. Sometimes they are associated with swelling under the skin, called angioedema, which burns more than itches and most often involves the eyelids, lips, tongue, hands and feet. Hives are caused by the release of one of the body's own chemicals, histamine, into the skin.
Histamine causes blood vessels to dilate, leaking fluid.
This leads to swelling and redness, along with intense itching. Sometimes it's very difficult to find out what's causing your hives. If it can be identified, the best course of treatment is avoidance of that substance. It's important to seek emergency care if you have hives and feel light-headed or have difficulty breathing or if hives continue to appear for more than a couple of days. Click here for more.