Featured Poison

Oleander: Poisonous and Kind of a Dick

A mystery writer friend asked me about oleander, the evergreen shrub that thrives throughout the southern United States, a little while back. Being the smart-ass that I am, I asked her who she was planning to kill and she said a dog. What, what, what? Relax, it’s a dog in the mystery novel she’s writing. I gave her my 60-second spiel on oleander poisoning, and then told her I’d just write about it. So here we are, let’s begin.

Oleander by Swaminathan (CC BY 2.0)

Oleander by Swaminathan (CC BY 2.0). Growing wild on the mean streets of Sunnyvale, California.

Oleander, Nerium oleander, and not to be confused with its cousin yellow oleander, thrives in sub-tropical regions where it is wet and warm. Good soil, bad soil, it doesn’t care, it’ll grow. Oleander probably originated in southeast Asia, though no one is 100% certain of that, and gradually migrated to the Middle East, North Africa, and the Mediterranean. As an evergreen it keeps its leaves throughout the year and blooms in the spring and summer with clusters of white, pink, or red flowers. By nearly any definition, it is a pretty plant, which is why it is used extensively for landscaping throughout the southern U.S. If you’re driving around in southern California, you’ll see it planted in the medians of the freeways, as landscaping for homes and businesses, and in wild open spaces. The same goes for the Gulf region of Texas, particularly Galveston, which is known as the “Oleander City.” Introduced to Galveston in the 1860’s by local businessman Joseph Osterman, who obtained it in Jamaica, oleander quickly spread throughout the island thanks to his sister-in-law, Isadore Dyer. And when Galveston was completely destroyed by a hurricane in 1900 – making landfall as a category-4 and killing ~10,000 – oleander was a natural and popular ornamental landscape choice for the rebuilding.

Much like “wild ginger“, traditional herbal remedies used oleander for thousands of years to treat vast arrays of illnesses. Even today, in relatively remote locales such as the South Pacific islands of Fiji, oleander is used to treat baldness, bruises, toothaches, and even syphilis (1). But is this a good idea? In a word, no.

Oleander, like all plants, contains dozens, if not hundreds, of natural products. The most prominent chemicals are cardiac glycosides like oleandrin, folinerin, and digitoxigenin. Of these, the most notable is oleandrin, and if the term cardiac glycoside rings a bell, congratulations, you read the post on foxglove and paid attention. Oleandrin, like digoxin found in foxglove, inactivates the sodium-potassium-ATPase pump. This deactivation causes an increase of intracellular sodium and calcium, and an increase in serum potassium, which is known as hyperkalemia. All together, the net effect is a decreased heart rate and increased cardiac contractility, which is a good thing if you have congestive heart failure. In toxic levels though, the myocytes (a type of muscle cell found in the heart) become sensitized to oleandrin, resulting in ventricular arrhythmias, a rapid heart beat that could lead to a loss of electrical activity in the heart (asystole) and sudden death (no explanation needed). (2)

Other clinical features are gastrointestinal and include nausea, vomiting, abdominal pain and diarrhea (or diarrhoea for you UK-ers). Neurologically one could expect tremors, drowsiness, and xanthopsia. Xanthopsia? That’s the increase of yellow in vision due to a yellowing of the eye’s lens, and a consequence of disrupting the sodium-pump. Treatment is typically activated charcoal to absorb the drug (use of gastric lavage is becoming less frequent), supportive care, and digoxin specific Fab antibody fragments given intravenously. Though oleandrin is not the same as digoxin, the treatment still works and greatly reduces fatalities, but is expensive. If you arrive at a U.S. emergency department unconscious, and the “wallet biopsy” shows you have good insurance, you may be in luck. (2)



Now there’s some good news, and some bad news. Mostly bad. Oleandrin is present in every part of the plant, from the roots, to the leaves, right out to the tips of the flowers. So any consumed part has the potential to be toxic, if not lethal. But the good news is that the oleander plant doesn’t produce nectar! Why on earth is that good news, you ask? Well, since we have so many of these flowering poisonous plants throughout the United States (and world), it’s nice that we can’t become sick from the honey of pollinating bees, like with “mad honey” and the grayanotoxins of the rhododendron. So without nectar, how does oleander become pollinated so it can flower? By being a dick, that’s how. In a nutshell, out-of-the-loop bees go to collect nectar from these dicks oleander flowers, pollinating them along the way, only to discover “Hey, there’s no nectar here. What a dick.” Botanists call it deceit pollination. I call it dick pollination.*

* I guess that’s how most animals reproduce. But I’ll stop, I can see this getting wayyy out of hand. That and I’m really twelve and can’t stop grinning.

Nerium oleander by Justin Brower

Nerium oleander by Justin Brower

The larger question is whether or not people become ill or die from oleander poisoning, and the answer is a resounding yes. You’ve got your accidental poisonings, suicides, homicides, and even the poisoning of livestock. Oleander doesn’t discriminate.

In an unusual case coming out of Italy, two young individuals, a man and a woman, were found dead in a forest (3). Both were malnourished, weighing 83 pounds each, and wearing shabby clothing, and with no money or provisions. Autopsy revealed no anatomical cause of death, but vegetal remains were found in their gastric contents (stomach). Using a radioimmunoassay the toxicologists detected oleandrin in both decedents and determined it to be the cause of death. It took 4 years though for the pair to be identified. The mother of the young woman, who was Belgian, told authorities her daughter had run away with a vegan 6 months before her death. Apparently this pair were “extreme vegans” because they somehow decided to only consume food that they could find while wandering about . . . in Italian woods, I suppose. Whether or not the emaciated pair ate oleander as a source of food or if it was a knowing suicide is impossible to determine, but the end result was the same.

This is just further confirmation that Nature’s Poisons are all around us, even in things that we plant on purpose for aesthetic reasons. So unless you know what you’re doing, don’t eat any strange plants. And remember, oleander’s a dick.

1. Singh, Yadhu N. “Traditional Medicine in Fiji: Some Herbal Folk Cures Used by Fiji Indians.” Journal of Ethnopharmacology 15.1 (1986): 57-88.
2. Bandara, Veronika, Scott A. Weinstein, Julian White, and Michael Eddleston. “A Review of the Natural History, Toxinology, Diagnosis and Clinical Management of Nerium Oleander (common Oleander) and Thevetia Peruviana (yellow Oleander) Poisoning.” Toxicon 56.3 (2010): 273-81.
3. Papi, Luigi, Alessandro Bassi Luciani, David Forni, and Mario Giusiani. “Unexpected Double Lethal Oleander Poisoning.” The American Journal of Forensic Medicine and Pathology 33.1 (2012): 93-97.

20 thoughts on “Oleander: Poisonous and Kind of a Dick

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  3. Thanks for the interesting information. Another “virtue” of oleander, although only slightly related to this topic –it brought with it the oleander aphid (Aphis nerii) which is wreaking havoc with milkweeds (Asclepias spp.) to the despair of monarch lovers. Milkweeds and oleander are related and share some of the chemicals that make them so toxic. The aphids are adapted to these chemicals and were able to make the transition from the introduced plant to the native ones. But oleander has some defenses against this formidable aphid and keeps it under control. Not so the milkweeds. Their infestations are epic. Some predators get sick when they eat the aphid.

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  6. Thanks for the information, I always enjoy reading your posts. This one brings to mind a fascinating paper from JAT in 2006: “Unexpectedly Dangerous Escargot Stew: Oleandrin Poisoning through the Alimentary Chain”. Kudos to all involved for their determination in identifying this toxin correctly.

  7. I grew up in central Florida being told that oleander is particularly dangerous as a “silent killer” because of the toxin being carried in the smoke when the plant is burned. One story said that a group of young people camped along a causeway where oleander grew, and added it to their campfire, causing all of them to eventually pass out and die. However, there is no mention at all, here, of inhalation…Is it actually only ingestion that kills people?

    • I hadn’t heard that one. But there is a similar one about a group of campers (Boyscouts?) that used oleander sticks to roast their hotdogs, which poisoned them – there’s no proof of that happening.

      My first, gut-reaction is that oleandrin wouldundergo pyrolysis – thermal degradation – upon burning the oleander twigs, not to mention being out in the open making it difficult to achieve toxic concentrations, but I did look into it.

      Seems a family of four burned oleander and became ill. ECGs showed digoxin-like ST-T-wave changes consistent with oleandrin toxicity. They recovered just fine after a few days. http://www.ncbi.nlm.nih.gov/pubmed/21397908

      So there you go. Don’t burn oleander either! Thanks for the comment!

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  9. “If you arrive at a U.S. emergency department unconscious, and the “wallet biopsy” shows you have good insurance, you may be in luck.”

    I realize that much of this is written in a tongue in cheek style, but really? We don’t treat based on insurance in the ER, or in the unit, or in any hospital I have ever worked at except one that was affiliated with a certain large HMO.

    I cannot tell you how many patients we treat with a social security number of 000-00-0000 who have no insurance whatsoever. Stroke, STEMI, Trauma, they all get treatment. It isn’t contingent on insurance. I have seen surgeons operate for free. I wish people would stop with this bullshit.

    • Definitely “tongue-in-cheek”, but there is truth in it. Despite the Emergency Medical Treatment and Active Labor Act that makes it a Federal law that all critically ill patients receive care, it doesn’t necessarily mean that all care is equal. Insurance discrimination definitely exists (though not in your facility, which is great for you and your community!).

      (For those unfamiliar with this topic, here’s an article from the Washington Post: http://www.washingtonpost.com/wp-dyn/content/article/2008/10/10/AR2008101002679.html)

      • I ran across this lovely article searching about Oleander’s toxicity to bees, we have two beautiful plants on our balcony in Athens, Greece and my husband does all the pruning and plant care and he had some days of arythmia, we attribute this “dick” plant for his ailments. Anyhoo, this person may gladly treat a person in ER without insurance, but no matter what, the victim will be charged immoral amounts of money for care and be chased by bill collectors too. Thankfully, I now live in a country that is rife with oleander but free from the dickish healthcare I experienced all my life in the US.

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  12. Thanks for the info. Those Oleanders and lillies are so beautiful. Shame they’re poisonous! I have a little dog, so I’m digging up all my lillies where he plays. I sure didn’t know they were dangerous! Are they poisonous to humans too? Thank you!

  13. As Cassandra Quave, assistant professor of Dermatology and Human Health at Emory University explains on The Conversation, oleandrin is derived from the oleander plant, which is toxic and can have seriously negative effects on the human heart. She stresses that there are no studies proving it is safe to ingest.

  14. Isn’t it remarkable how nobody mentions it’s effects on many cancers. It’s also damn remarkable how many universities are secretly studying it. It’s even more remarkable how an entire commercial production lab and hospital have been built in Honduras based on a product produced from the plant. Which is grown in Texas and exported there. All rather remarkable business indeed…

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