Nerium oleander is a common shrub in temperate and subtropical regions, frequently used in landscaping for its hardiness and vibrant pink, red, or white blooms. Despite its ornamental appeal, oleander is one of the most poisonous plants commonly grown, posing a significant risk if mishandled or ingested. The plant typically grows as a dense, evergreen shrub or small tree with long, leathery leaves. Understanding its toxicity is paramount for public safety.
The Compounds Responsible for Toxicity
The danger posed by oleander stems from potent compounds known as cardiac glycosides. The primary toxins are oleandrin and nerioside, found in all parts of the plant, including the leaves, stems, flowers, roots, and sap. Even smoke from burning oleander wood or branches contains these toxic substances, which can cause respiratory distress if inhaled.
These cardiac glycosides interfere directly with the sodium-potassium pump (Na+/K+-ATPase) in cell membranes, particularly in the heart muscle. By inhibiting this pump, the compounds disrupt the delicate balance of electrolytes within the heart cells. This inhibition leads to an accumulation of sodium ions inside the cell, which in turn causes an increase in intracellular calcium.
The resulting high calcium levels alter the heart’s electrical activity and mechanical function, making the compounds potent cardiotoxins. This mechanism is similar to that of the prescription heart medication digoxin, meaning oleander poisoning mimics a severe digoxin overdose. The toxic dose can be remarkably small; ingestion of approximately four grams of oleander leaf may be lethal to an adult.
Recognizing the Signs of Poisoning
Symptoms of oleander poisoning affect the gastrointestinal, cardiac, and central nervous systems, often appearing within a few hours of ingestion. The initial presentation is dominated by gastrointestinal distress, including nausea, vomiting, abdominal pain, and diarrhea, which may occasionally be bloody.
The most serious and life-threatening effects are on the cardiovascular system, driven by the action of the cardiac glycosides. Cardiac symptoms include a slow or irregular heartbeat (bradycardia or various dysrhythmias), which can progress to severe heart blocks or ventricular fibrillation. Patients may also experience low blood pressure and general weakness as the heart struggles to pump effectively.
Beyond the heart and digestive tract, the central nervous system (CNS) can also be affected. CNS manifestations may include confusion, dizziness, drowsiness, or lethargy. In severe cases, a person may experience tremors, seizures, or even coma.
What to Do in Case of Exposure
If exposure to any part of the oleander plant is suspected, immediate action is paramount. Call emergency services, such as 911, or contact a local Poison Control Center immediately for expert guidance. Provide the professional with the person’s age, weight, the amount and part of the plant involved, and the time of exposure.
While awaiting professional help, remove any remaining plant material from the mouth. If the sap has contacted the skin or eyes, thoroughly rinse the affected area with water. Do not attempt to induce vomiting unless specifically instructed to do so by a medical professional or Poison Control, as inducing vomiting can sometimes worsen the clinical situation or increase the risk of aspiration.
Once at a medical facility, treatment is focused on supportive care and managing the cardiotoxicity. Interventions may include administering activated charcoal to absorb toxins in the digestive tract, especially if the ingestion was recent. For severe cases involving life-threatening arrhythmias, the highly specific antidote, Digoxin-specific antibody fragments (Fab), may be used, as it binds to the cardiac glycosides.
Preventative measures are the most effective way to avoid poisoning. Never use oleander branches or wood for cooking, skewers, or campfires, as the toxins can leach into food or be released in smoke. When pruning or handling the plant, wear gloves to avoid contact with the irritating sap. Ensure all clippings are disposed of safely; never composting or burning them due to the toxic smoke hazard.