Oleander is one of the most poisonous plants and contains numerous toxic compounds, many of which can be deadly to people, especially young children. The toxicity of Oleander is considered extremely high and it has been reported that in some cases only a small amount had lethal or near lethal effects (Goetz 1998). The most significant of these toxins are oleandrin and neriine, which are cardiac glycosides (Goetz 1998). “Cardiac glycocides are naturally occurring” plant or animal compounds “whose actions include both beneficial and toxic effects on the heart” (Desai 2000). They are present in all parts of the plant, but are most concentrated in the sap. It is thought that Oleander may contain many other unknown or un-researched compounds that may have dangerous effects (Inchem 2005). Oleander bark contains rosagenin which is known for its strychnine-like effects. The entire plant including the milky white sap is toxic and any part can cause an adverse reaction. Oleander is also known to hold its toxicity even after drying. It is thought that a handful or 10-20 leaves consumed by an adult can cause an adverse reaction, and a single leaf could be lethal to an infant or child. According to the Toxic Exposure Surveillance System (TESS) in 2002 there were 847 known human poisonings in the United States related to Oleander (Watson 2003). In animals, around 0.5 mg per kilogram of body weight is lethal to many animals, and various other doses will affect other animals (Inchem 2005). Most animals can suffer a reaction or death from this plant.

Effects of poisoningReactions to this plant are as follows. Ingestion can cause both gastrointestinal and cardiac effects. The gastrointestinal effects can consist of nausea and vomiting, excess salivation, abdominal pain, diarrhea that may or may not contain blood, and especially in horses, colic (Inchem 2005). Cardiac reactions consist of irregular heart rate, sometimes characterized by a racing heart at first that then slows to below normal further along in the reaction. The heart may also beat erratically with no sign of a specific rhythm. Extremities may become pale and cold due to poor or irregular circulation (Goetz 1998). Reactions to poisonings from this plant can also affect the central nervous system. These symptoms can include drowsiness, tremors or shaking of the muscles, seizures, collapse, and even coma that can lead to death (Goetz 1998). Oleander sap can cause skin irritations, severe eye inflammation and irritation, and allergy reactions characterized by dermatitis (Goetz 1998).
Medical treatment requiredPoisoning and reactions to Oleander plants are evident quickly, requiring immediate medical care in suspected or known poisonings of both humans and animals (Goetz 1998). Induced vomiting and gastric lavage are protective measures to reduce absorption of the toxic compounds. Charcoal may also be administered to help absorb any remaining toxins (Inchem 2005). Further medical attention may be required and will depend on the severity of the poisoning and symptoms.
Drying of plant materials does not eliminate the toxins. It is also hazardous for animals such as sheep, horses, cattle, and other grazing animals, with as little as 100 g being enough to kill an adult horse (Knight 1999). Plant clippings are especially dangerous to horses, as they are sweet. Symptoms of a poisoned horse include severe diarrhea and abnormal heartbeat. There are a wide range of toxins and secondary compounds within Oleander, and care should be taken around this plant due to its toxic nature. Different names for Oleander are used around the world in different locations (see top of page); so when encountering a plant with this appearance, regardless of the name used for it, exercise great care and caution to avoid ingestion of any part of the plant, including its sap and dried leaves or twigs. Do not use the dried or fresh branches for spearing food, in preparing a cooking fire, or as a food skewer. Many of the Oleander relatives, such as the Desert Rose (Adenium obesum) found in East Africa, have similar leaves and flowers and are equally toxic.
Trunk oilWhile the reasons are unknown, some visibly healthy oleander shrubs that have become sick or otherwise diseased may generate a type of oil from the trunk and shallow roots. Depending upon the size of the shrub, the oil quantity can vary greatly and has the capability to saturate the soil in its vicinity as the shrub’s sickness progresses. This is possibly an explanation for the plant’s name of “Olea”, whose Latin translation is “oil”. The oil is light-brown colored and possesses a rancid scent. The toxicity of the oil is unknown, because the neuro-toxic chemicals in the rest of the tree come from the leave’s vein-system and not from the actual pulp surrounding these veins. There is even a species of large, green caterpillar who feeds specifically on oleanders and survives by eating only the pulp surrounding the leaf-veins, avoiding the fibers.