Background: Many plants, including Nerium oleander, contain cardiac glycosides. The cardiac glycosides in Nerium oleander have more digestive effects than digoxin, with symptoms ranging from nausea and vomiting to muscle cramps and bloody diarrhea. The common oleander plant (Nerium oleander) is poisonous and potentially lethal. All parts of it, including the root, stem, and leaves, contain various digoxin-like cardiac glycosides. Case Presentation: A 34-year-old woman from Boshruyeh complained of headache, lightheadedness, nausea, and abdominal pain approximately 5 hours after consuming an unknown amount of Nerium oleander leaves in the form of a decoction. We studied a case report of common oleander poisoning, which presented with clinical manifestations of headache, lightheadedness, nausea, and abdominal pain. The patient had bradycardia and some degree of heart block and was discharged after 3 days in good general condition following treatment with atropine injection and other supportive measures. Conclusions: Although both Nerium oleander and digoxin are glycosides, Nerium oleander does not raise digoxin levels. Like digoxin, which affects the AV and SA nodes, this plant causes negative inotropic and blocking effects in the SA and AV nodes, leading to bradycardia. (Iranian Heart Journal 2024; 25(4): 96-99)