Which plant is associated with cardiotoxicity due to grayanotoxins (grayanotoxicosis)?

• A. azalea (rhododendron)
• B. monkshood (aconitum)
• C. perilla (perilla)
• D. red maple (acer)

Answer: (A)

Grayanotoxins are toxins produced by certain Rhododendron plants, including azaleas, and they cause cardiotoxicity by binding to voltage-gated sodium channels in cardiac cells. This keeps the channels open, leading to persistent depolarization, disrupted conduction, and outcomes such as bradycardia, hypotension, and sometimes heart block. Exposure can occur through ingestion of plant material or honey made from nectar of these plants (mad honey). Among common ornamental plants, azalea (a Rhododendron) is the classic source of grayanotoxin-related cardiotoxicity. Monkshood contains a different toxin (aconitine), while perilla and red maple are not associated with grayanotoxins.