Urticarial reactions are truly, in their purest sense, simply a "nuisance" reaction, much like the febrile nonhemolytic reaction. We see these things a lot, and they simply, in most cases, are no big deal.
Some people think of urticarial reactions as part of a spectrum, with simple skin-limited reactions on one end and severe, life-threatening anaphylactic reactions at the other. I guess that's OK, but the truth is that people rarely actually progress along that spectrum, and, in fact, the mechanisms may be completely different at the opposite ends.
For now, though, let's begin with a discussion of the presentation of urticarial reactions. If you want, you can skip ahead to the pathophysiology, treatment, or prevention of these reactions.
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