# Oleander (Nerium oleander) *Rose bay, rose bay tree, laurel rose; French *laurier rose*; Spanish *adelfa*; Italian *Ammazza l’Asino*, ‘Ass-bane,’ and in Tuscany *Mazza di San Giuseppe*, ‘St. Joseph’s Staff’; *Nerium oleander* L.* **Known today as.** *Nerium oleander*, of the family Apocynaceae, an evergreen shrub up to about four metres, with narrow, leathery leaves usually in threes and clusters of five-petalled flowers, pink or white in the wild form and of many colours in some four hundred cultivars. A broken twig exudes a thick white sap. The poisons monograph of the International Programme on Chemical Safety gives it as native only to the Mediterranean, where it grows along watercourses and in damp ravines, and cultivated worldwide as an ornamental. Its poisons are cardiac glycosides, chief among them oleandrin. Kind: Plant Poisoning: Cardiac glycoside poisoning (https://thethinkingpress.org/materia-medica/poisons/cardiac-glycoside) Deadly: yes > **Deadly.** The monograph states that all parts of the plant, including the sap, are toxic whether fresh, dried, or boiled. Poisoning usually begins with nausea, vomiting, abdominal pain, and diarrhoea, followed by slowing of the heart and heart block, and in severe cases by ventricular arrhythmias, which are the cause of death; tremor, drowsiness, and seizures may occur. Children playing with the shrub are among those most at risk, and in Australia and southern Africa swallowing parts of it is one of the major causes of children’s admission to hospital; poisoning has also come from herbal infusions taken as medicine. The botanical.com addition warns that the smoke of burning wood can cause severe irritation. ## What was it used for? A poison more than a medicine. The monograph records that preparations of its active principles were formerly used as rat poisons and insecticides and as remedies for indigestion, fever, ringworm, malaria, leprosy, and venereal disease, and as abortifacients, and that oleander glycosides were assessed as heart drugs in the 1930s. King’s Dispensatory of 1898, finding that its action had been compared to that of digitalis, thought it worth investigation as a heart remedy and reported that it had been found to slow the heart and relieve dropsy and breathlessness in valvular disease. ## What does modern science say? No European monograph covers it. The poisons monograph, written in 1989, records that the USSR pharmacopoeia contained oleandrin preparations, but treats the plant itself only as a poison. ## Pharmacognosy and toxicology - **oleandrin**: the main toxin, a cardiac glycoside, about 0.08 per cent of the plant tissues - **cardiac glycosides**: more than ten of known structure **Mechanism.** King’s records that the action of its constituents had been compared to that of digitalis; the poisons monograph records slowing of the heart, heart block, and ventricular arrhythmias, from which death comes. **Standing.** No medicinal use of the plant in Europe. The poisons monograph (1989) records oleandrin preparations in the USSR pharmacopoeia. ## What lore surrounds it? Folkard calls it a plant of “a funereal and sinister character,” thought ill-omened in Italy and bringing disgrace and misfortune; in Tuscany and Sicily the dead were covered with its blossoms, and in India chaplets of its flowers were laid on their brows. The Hindus, he says, called it the “Horse-killer,” and the Italians Ass-bane, for the animals that die of eating it. A Tuscan legend has it that St. Joseph’s staff blossomed into oleander the moment he took it in his hands. King’s records the stories that honey from its flowers is poisonous and that the scent of the flowers in a bedroom had caused death. ## What did the older authorities say? **Gerard, *The Herbal* (1633 edition), as quoted on botanical.com.** “This tree being outwardly applied, as Galen saith, hath a digesting faculty; but if it be inwardly taken it is deadly and poisonsome, not only to men, but also to most kinds of beasts.” Its flowers and leaves, Gerard went on, kill dogs, asses, mules, and many other beasts, and sheep and goats that drink water in which the leaves have been steeped “are sure to die.” The passage is quoted in an addition to Grieve’s herbal made by its online publisher, not in Grieve’s own text. ## Sources - International Programme on Chemical Safety. *Nerium oleander L.* Poisons Information Monograph 366. INCHEM. - Felter, H. W., & Lloyd, J. U. (1898). *King’s American Dispensatory*, vol. 2, “Oleander.” Internet Archive, kingsamericandis02kinguoft. - Folkard, R. (1884). *Plant Lore, Legends, and Lyrics*, “OLEANDER.” Project Gutenberg, 44638. - Grieve, M. *A Modern Herbal*, “Oleander.” As published on botanical.com. - International Programme on Chemical Safety. *Nerium oleander L.* Poisons Information Monograph 366. INCHEM. - Felter, H. W., & Lloyd, J. U. (1898). *King’s American Dispensatory*, vol. 2, “Oleander.” Internet Archive, kingsamericandis02kinguoft. --- *Oleander.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-17. The Thinking Press. https://thethinkingpress.org/materia-medica/oleander Historical description, not medical advice.