The plant containing the heart-affecting toxin oleandrin is oleander. Oleander is the common name for Nerium oleander, an evergreen shrub widely grown for its pink, white, or red flowers. It is native mainly to regions around the Mediterranean and parts of Asia, but is now cultivated in warm climates worldwide.
Oleandrin is a cardiac glycoside, a chemical class that includes compounds affecting the heart’s electrical activity and contractions. It interferes with the sodium–potassium ATPase system in a way broadly related to the action of digoxin. Oleander’s leaves, flowers, stems, sap, and other parts can all contain toxic cardiac compounds.
A common mix-up is foxglove, which also contains cardiac glycosides, but its best-known toxins are digitalis compounds rather than oleandrin. Oleander poisoning can cause nausea, vomiting, abnormal heart rhythms, confusion, and potentially fatal cardiac complications. Historically, oleander extracts appeared in folk remedies and pest-control practices, but modern medical sources do not consider them safe treatments.