Which symptom is NOT associated with anaphylaxis?

Anaphylaxis is a severe and potentially life-threatening allergic reaction characterized by a rapid onset of various symptoms that can affect multiple body systems. Symptoms commonly associated with this condition include swelling of the face and hands, labored breathing, and itching skin or hives.

Swollen face and hands can occur due to the release of histamines and other chemicals in response to an allergen, leading to edema. Labored breathing results from airway constriction or swelling in the respiratory tract, which is a critical and dangerous aspect of anaphylaxis. Itching skin and hives are also typical responses, stemming from the body's overreaction to an allergen, causing localized inflammation and irritation.

In contrast, difficulty sleeping is not a typical acute symptom of anaphylaxis. While anaphylaxis can cause considerable distress and anxiety which could indirectly affect sleep patterns, it is not a direct symptom associated with the immediate physiological responses of the body during an anaphylactic event. This makes difficulty sleeping the outlier among the listed symptoms.