Hives

Hives are usually an indication of an allergic reaction, although the exact cause is often difficult to pinpoint. The irritation can be caused by numerous circumstances, including environmental factors, like pet dander, dust mites, pollen or mold. Hives develop primarily as the result of certain cells in your body releasing histamine. This secretion of histamine traps fluid under your skin and this buildup causes the outbreak of Hives. Hives can last for a few minutes or hours and then disappear or last for weeks or months at a time.

Symptoms:

Localized redness, itching and swelling of your skin
Can appear round or flat in formation but will always be raised above the surrounding skin
Although broken or scabbing skin is not a direct symptom of Hives, it can result from scratching the affected area. Heat can also cause your Hives to worsen and spread. In extreme cases, your airways can swell, causing wheezing and respiratory distress, or even hindering your ability to breathe at all.