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ACEi Angioedema ARB Cross-Reactivity — RACP Adult Medicine MCQ

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ModerateClinical PharmacologyACEi Angioedema ARB Cross-ReactivityRACP Adult Medicine

A 62-year-old man with CKD stage 4 on ACEi develops a dry cough. He is switched to an ARB. Two months later, he develops facial angioedema. What is the likelihood of ARB cross-reactivity for ACEi-induced angioedema?

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Correct answer: A — Approximately 2–8% cross-reactivity risk

ACEi-induced angioedema is bradykinin-mediated (not allergic). ARBs do not directly affect bradykinin metabolism, so cross-reactivity is relatively low (~2–8%). However, some patients develop angioedema on ARBs through uncertain mechanisms. Most guidelines consider ARBs a reasonable alternative after ACEi angioedema, with appropriate counselling about the small residual risk and a monitoring period. For patients who develop angioedema on both ACEi and ARB, alternative antihypertensives must be used.

Reference: AMH – 2025 – ACE Inhibitors and ARBs; eTG – 2025 – Cardiovascular