People with allergy/hypersensitivity to oleander or other cardiac glycosides such as digoxin or digitoxin may have reactions to oleander. Skin contact with sap from oleander leaves may cause rash.
Side Effects and Warnings
Common oleander contains a strychnine-like toxin and a heart-active cardiac glycoside substance (similar to the prescription drug digoxin) that may cause the heart to beat rapidly, abnormally, or to stop beating. Common oleander has been used as rat poison, insecticide, and fish poison and is toxic to mammals including humans. Animals (sheep) have died after eating as little as two to three leaves of Nerium oleander (common oleander). Children may die after eating a single leaf of common oleander. Eating the leaves, flowers, or bark of common oleander may cause nausea, vomiting, stomach cramps, pain, fatigue, drowsiness, unsteadiness, bloody diarrhea, abnormal heart rhythms, seizures, liver or kidney damage, or unconsciousness. Death may occur within one day. Reports of toxicity and deaths in children and adults have been reported for decades in Australia, India, Sri Lanka, and the United States.
Fruits of Thevetin peruviana (yellow oleander) are thought to be even more toxic to mammals, including humans. Based on human studies of intentional overdose (suicide attempts), eating eight or more seeds of yellow oleander may be fatal. Additional side effects of oleander ingestion include irritation and redness of lips, gums, and tongue, nausea, vomiting, depression, irritability, fast breathing, sweating, stomach pain, diarrhea, headache, confusion, visual disturbances, and constricted pupils. Abnormal blood tests, including tests of liver and kidney function (potassium, bilirubin, creatinine, and blood urea), have been reported in humans.
It is possible that plants grown in the same soil as oleander plants or in soil exposed to oleander may contain trace amounts of oleander.
Pregnancy and Breastfeeding
Oleander is toxic and should be avoided by pregnant or breastfeeding women.
Adults (18 years and older)
Safety has not been established for any dose of oleander. Peruvoside, a heart-active substance in yellow oleander kernels (similar to the drug digoxin), has been studied at 1.8 to 3.2 milligrams by mouth, as an initial dose, followed by an average daily dose of 0.6 milligrams per day for congestive heart failure.
Children (younger than 18 years)
Oleander is not recommended for use in children due to risk of toxicity or death and lack of scientific data.
Interactions with Drugs
Based on animal and human studies, common oleander and yellow oleander contain cardiac glycoside heart-active substances similar to the drug digoxin. There may be an increased risk of unwanted side effects or damage to the heart if taken with other heart-active drugs, such as digoxin (Lanoxin®) or anti-arrhythmics.
Because oleander is similar to the drug digoxin, it may share some of the same interactions, although this has not been thoroughly studied.
Low potassium levels in the blood may increase the dangerous side effects of oleander. Therefore, oleander should be used cautiously with drugs that may lower potassium levels, such as laxatives or some diuretics (drugs that increase urine flow).
Oleander may interact with abortifacients, antibiotics, antidepressants, blood pressure-lowering drugs, antineoplastics, contraceptives, hormonal drugs, immunosuppressants, and neurologic drugs.
Common oleander and yellow oleander contain cardiac glycoside heart-active substances and interact with other herbs or supplements with similar effects such as hawthorn. Notably, bufalin/Chan Suis is a Chinese herbal formula that has been reported as toxic or fatal when taken with cardiac glycosides.
Toxic effects of oleander on the heart may be increased if used with calcium supplements or herbs that lower potassium levels, such as licorice. Potassium levels theoretically may be reduced by herbs and supplements with laxative properties such as senna or psyllium or herbs and supplements with diuretic properties (increasing urine flow) such as artichoke, celery, or dandelion.
Oleander may interact with abortifacients, antibiotics, antidepressants, blood pressure-lowering herbs and supplements, antineoplastics, contraceptives, hormonal herbs and supplements, immunosuppressants, and neurologic herbs and supplements.