The clinical manifestations of systemic anaphylaxis in man include (1) respiratory distress caused by bronchospasm or angioneurotic edema involving the larynx; (2) diffuse erythema, urticaria, and pruritus; (3) vomiting, abdominal cramps, and diarrhea that occasionally is bloody; and (4) vascular collapse without preceding respiratory distress.
In fatal cases, the postmortem findings fall into three patterns: (1) acute pulmonary emphysema, revealed by gross and microscopic examination, and presumably resulting from obstruction in the lower respiratory tract; (2) edema of the upper respiratory tract, including the hypopharynx, epiglottis, larynx, and even the trachea; and (3) no significant findings despite an early and complete examination. The postmortem examinations of patients who died of asphyxia with secondary vascular collapse reveal acute pulmonary emphysema, laryngeal obstruction, or both, whereas there are no significant findings when the patient has died in a state of shock without antecedent respiratory difficulty. Fatal anaphylaxis with acute emphysema is similar
Austen KF. Systemic Anaphylaxis in Man. JAMA. 1965;192(2):108-110. doi:10.1001/jama.1965.03080150038007