Angioedema is a special form of urticaria. It is distinguished by swelling on the face, particularly the lips, the eyelids ("slitty eyes"), some of the mucous membranes, and other parts of the body. There is no itching, but instead a painful or burning sensation.

Quincke's disease, another type of urticaria, may become dangerous if it attacks the mucous membranes of the mouth and pharynx.

A swollen tongue or swollen back of the mouth blocks the breathing passages, so the victim could choke or even suffocate.