Case Presentation: An 86 year old male with a history of hypertension treated with long-term lisinopril presented with abrupt onset of unilateral left-sided facial swelling accompanied by a change in voice. Physical examination demonstrated asymmetric edema involving the face, tongue, and neck. Cross-sectional imaging confirmed soft-tissue swelling consistent with angioedema.The patient received emergent management with antihistamines, systemic corticosteroids, intramuscular epinephrine, tranexamic acid, and fresh frozen plasma, resulting in marked improvement in edema. He was admitted to the intensive care unit for airway monitoring and subsequently transferred to a general medical ward as symptoms continued to resolve. Work up was negative for infectious etiology, including cellulitis, parotitis, abscess, odontogenic infections, or sinusitis. Lisinopril was identified as the most likely precipitating factor and was discontinued permanently, with complete resolution of the angioedema and no further recurrence during hospitalization.
Discussion: ACE inhibitor–induced angioedema is an uncommon but clinically significant adverse reaction, occurring in approximately 0.1%–1% of treated patients.1 Most episodes involve bilateral swelling of the lips or tongue, but unilateral tongue angioedema is distinctly rare and can easily be mistaken for infectious or structural pathology.2,4 The bradykinin-mediated mechanism—resulting from impaired degradation of vasoactive peptides—accounts for the slower onset, absence of urticaria, and lack of allergic triggers, distinguishing it from histamine-mediated angioedema.5 As the tongue is densely vascular and highly sensitive to bradykinin, even mild accumulation can produce marked edema.2Previous case reports suggest that asymmetry of the lingual nerve may create localized differences in the chemical microenvironment, predisposing one side of the tongue to greater bradykinin sensitivity.3,4 Structural boundaries within the tongue, such as fibrous septa, may also initially restrict edema spread.6 In some instances, unilateral swelling has progressed to involve the oropharynx, face, or cervical soft tissues, mimicking deep neck space infections and complicating prompt diagnosis.7 Management centers on immediate cessation of the ACE inhibitor and close airway surveillance. Although most unilateral cases resolve with supportive care alone, the potential for rapid progression warrants early recognition and readiness for advanced airway intervention.2,7
Conclusions: Unilateral tongue angioedema represents an uncommon variant of ACE inhibitor–induced angioedema. Clinicians should maintain a high index of suspicion for ACE-I–related angioedema in any patient presenting with isolated or asymmetric tongue swelling, as timely identification and management are essential to preventing progression and ensuring patient safety.