Yellow oleander (Thevetia peruviana), which belongs to the Apocyanaceae family, is a common shrub seen throughout the tropics. Deliberate self-harm by consumption of this plant is a common toxicological emergency in South Asian countries, especially in India and Sri Lanka. Ingestion of any part of this plant is toxic, as all parts contains a variety of cardiac glycosides including neriifolin, thevetin A, thevetin B, oleandrin, and other unidentified substances.

Ingestion of yellow oleander (Thevetia peruviana) results in clinical symptoms similar to those of digitalis toxicity. Common symptoms include nausea, vomiting, abdominal pain, diarrhea, dysrhythmias, and restlessness. A common electrolyte abnormality is hyperkalemia. Cardiac toxicity, due to the cardiac glycosides, is a common life-threatening clinical manifestation. Patients may develop bradycardia with atrioventricular (AV) block, atrial tachycardias, ventricular tachycardia including bidirectional ventricular tachycardia, and ventricular fibrillation. Cardiogenic shock with myocardial depression can also occur. The arrhythmogenic effects of the cardiac glycosides are caused due to a combination of the direct effects of the toxin on the myocardium and the conducting system of the heart and the neurally mediated increases in autonomic activity.

Cardiac glycosides exert various direct cardiotoxic effects through a variety of mediators such as histamine, nitric oxide, leukotrienes, endothelin, angiotensin, and superoxide radicals. Increased central sympathomimetic activity on the heart also plays an important role in the development of cardiac arrhythmias in patients with cardiac glycoside poisoning. Hence, the use of parasympathetic system blockade with atropine, or the use of β-adrenergic agonists, may result in tachyarrhythmias.
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