Abstract
The wheel and flare of urticaria is the pathognomonic feature of histamine-mediated cutaneous lesions. In fact, urticaria is one of the most common chief complaints encountered by dermatologists. Fortunately, their life-threatening sequelae, namely, anaphylaxis and shock, are exceedingly rare. Understanding the mechanisms through which histamine release occurs and its subsequent physiologic and potentially pathologic impact is vital to our ability to triage and treat appropriately. All dermatologists should be proficient at recognizing and diagnosing both common and unusual histamine-mediated emergencies in order to implement timely and directed therapy that could be potentially lifesaving.