Hereditary Angioedema

A patient with a swollen lip may appear stable while a parallel attack is developing in the larynx or gastrointestinal tract. In hereditary angioedema caused by C1-INH deficiency, the swelling is driven by bradykinin rather than histamine, so the usual allergy medications do not stop the process. The clinical sequence is therefore distinctive: recognize nonurticarial swelling, confirm the C1-INH disorder with complement testing, treat attacks early with HAE-specific therapy, and protect the airway whenever the upper airway may be involved. Canadian prescribing decisions should follow the current Health Canada product monograph, provincial access pathways, and specialist-directed care.