Which of the following is considered a sign of anaphylaxis?

Severe urticaria, commonly known as hives, is a significant indicator of anaphylaxis, a serious allergic reaction that can occur rapidly and can be life-threatening. In the context of anaphylaxis, urticaria may appear as raised, red welts on the skin and is typically accompanied by other more critical symptoms such as difficulty breathing, swelling of the face or throat, and gastrointestinal disturbances.

The presence of severe urticaria is particularly concerning because it often signifies that the body is responding intensely to an allergen. This response indicates that the immune system is releasing a large amount of histamine and other chemicals, which can lead to the narrowing of airways and increased vascular permeability, thus heightening the risks associated with anaphylaxis.

Other symptoms like a mild rash, headache, or a runny nose are generally indicative of less severe allergic reactions or other medical conditions, but do not typically reflect the severe systemic response that characterizes anaphylaxis. Therefore, recognizing severe urticaria in conjunction with other symptoms can be vital for timely intervention and management of anaphylactic shock.