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Description:

N. oleander is an evergreen shrub (or small tree) that is frequently cultivated as a garden ornamental. It has dark green, narrow lanceolate, leathery, hairless leaves, showy white, pink or red flowers in clusters at the end of the branches, and long slender 2-lobed pods with seeds covered in brown hairs.  

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Toxin

Every part of the plant contains oleandrin and neriine, highly toxic cardiac glycosides. These toxins are toxic to both humans and plants. In general, the rate of mortality among humans is fairly low but the leaves are lethal when ingested by a small child. As little as 100g of the plant can kill an adult horse. 

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How the toxin works?

When the plant is ingested, toxins work by inhibiting Na+/K+ATPase pump resulting in the decrease of intracellular potassium, an increase in extracellular (serum) potassium, and accumulation of sodium inside the cell. The secondary calcium buildup, leads to an increased cardiac contractility and eventually death.

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Symptoms of the poisoning

Ingesting oleander can cause both gastrointestinal and cardiac effects. The gastrointestinal effects may include dry mouth or excess salivation, pain in the oral cavity, nausea, vomiting, abdominal pains, cramps and bloody diarrhoea. The cardiac effects may include cardiac disturbances which can include dysrhythmias, a decrease in blood pressure, slowed pulse, irregular heartbeat, dilation of pupils, drowsiness, and cardiac arrhythmia. Other symptoms are confusion and dizziness.

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Treatment

Oleander poisoning may be addressed by emesis (inducing vomiting) to detox (eradicate the poison from the body). Although this is only used for life-threatening conditions due to side-effects.

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Uses:

Common oleander has been used as rat poison, insecticide, and fish poison. Although poisonous, the leaves and flowers are cardiotonic, diaphoretic, diuretic, emetic, expectorant, and sternutatory agents. Hence:

• The leaves are boiled and the liquid is applied externally to treat scabies and reduce swellings.
• The roots are pounded into a paste that is applied externally to chancres and ulcers on the penis. 
• The oil made from the root bark is applied externally to treat leprosy and scaly skin.

The plant has been used to treat cardiac-related illnesses and oleandrin has been reported to inhibit the growth of human cancer cells. 

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Drying the plant does not eliminate the toxins.When applied topically, it may cause irritation. Care should be taken around the plant due to its toxic nature

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Reference and further reading:

1. Ayouaz, S., Arab, R., Mouhoubi, K. and Madani, K., 2023. Nerium oleander L.: A review of chemical, pharmacological and traditional uses. J. Biomed. Res. Environ. Sci, 2766, p.2276.
2. Bouabidi, A., Romdhane, M. and Saadaoui, E., 2025. Nerium oleander L.: A review of diversity, toxicity, chemical compositions and biological activities. Biologica Nyssana, 16(1).
3. Ebrahimi, F., Ghorbani Nohooji, M. and Miri, S.M., 2018, October. Agronomic and pharmacological aspects of Nerium oleander: an important medicinal plant. In The first national congress and international fair of medicinal plants and strategies for Persian medicine that affect diabetes (pp. 9-11).
4. Kalita, K. and Raina, D., 2024. Potential of Nerium oleander as a traditional medicine: A review of phytoconstituents and CNS-depressant properties. South African Journal of Botany, 173, pp.411-416.
5. Sangeetha, S., Saravanakumar, A., Parthiban, P. and Pavithra, R., 2025. A Review on Pharmacological Properties, Therapeutic Applications of Nerium oleander. Journal of Pharma Insights and Research, 3(4), pp.216-227.
6. Seher, A., Hanif, M.A., Ayub, M.A., Jilani, M.I. and Mahomoodally, M.F., 2020. Oleander. In Medicinal Plants of South Asia (pp. 525-539). Elsevier.
7. Shridhar, N.B., 2022. Nerium oleander toxicity: A review. Int. J. Adv. Acad. Stud, 4(10), pp.23-32.
8. Tiwari, E. 2020. Poisonous and medicinal properties of Nerium oleander. Research Times vol 9. ISSN 2395-051X.