Oleander Toxic?

Updated 2026-03-06| 4 min read| 941 found this helpful

All parts of oleander, including dried forms and occasionally honey made from it, are toxic, with highest glycoside content during flowering season

It contains cardiac glycosides that trigger cardiac dysfunction, and can cause death in humans, cats, dogs, horses, birds and other species

Horses and ducks are most sensitive to oleander poisoning, even dried oleander leaves can cause fatalities in swans

FAQ

Is Oleander toxic to Humans?

Vomiting, colic, possibly bloody diarrhea, mucosal irritation, tachypnea, mydriasis, cardiac arrhythmia, cold extremities, death from cardiac paralysis (Severe)

Is Oleander toxic to Cats?

Drooling, abdominal pain, diarrhea, depression, cardiac arrhythmia, potential fatal outcome (Severe)

Is Oleander toxic to Dogs?

Drooling, abdominal pain, diarrhea, colic, depression, apathy, vomiting, hypothermia, bradycardia, partial AV block, possible recovery after 4 days of treatment, fatal outcome in severe cases (Severe)

Is Oleander toxic to Horses?

Colic, weakness, bradycardia, arrhythmia, muscle tremors, depression, potential fatal outcome, horses are highly sensitive to oleander poisoning (Severe)

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Toxicity Details

Humans

Severe

Vomiting, colic, possibly bloody diarrhea, mucosal irritation, tachypnea, mydriasis, cardiac arrhythmia, cold extremities, death from cardiac paralysis

Cats

Severe

Drooling, abdominal pain, diarrhea, depression, cardiac arrhythmia, potential fatal outcome

Dogs

Severe

Drooling, abdominal pain, diarrhea, colic, depression, apathy, vomiting, hypothermia, bradycardia, partial AV block, possible recovery after 4 days of treatment, fatal outcome in severe cases

Horses

Severe

Colic, weakness, bradycardia, arrhythmia, muscle tremors, depression, potential fatal outcome, horses are highly sensitive to oleander poisoning

Toxicity Snapshot

Toxic PartsAll fresh or dried plant parts, occasional honey made from oleander nectar; leaves contain ~1% glycosides, red flowers have higher content than white flowers

Exposure RouteIngestion (consuming plant parts, oleander tea, contaminated honey, accidental ingestion of dried leaves by livestock/pets)

Toxic CompoundsOleandrin; Nerigosid; Odorosid A; Gentiobiosyloleandrin; Glucosyloleandrin; Other cardiac active steroid glycosides

First Aid & Prevention

First 30 Minutes

• Immediately stop exposure to oleander, do not induce vomiting unless instructed by a medical/vet professional
• Rinse mouth thoroughly with clean water if the plant was ingested
• Collect remaining plant parts for identification to support subsequent treatment

Contact Vet Immediately

• If oleander ingestion is confirmed or suspected, regardless of initial symptoms
• If symptoms like drooling, vomiting, abdominal pain, abnormal heart rate appear after exposure
• If the exposed individual shows loss of consciousness, breathing difficulty or irregular heartbeat

Prevention

• Keep oleander plants out of reach of children, pets and livestock
• Never use oleander branches as cooking skewers, or brew tea from any part of the plant
• Avoid letting livestock/poultry graze in areas with growing or discarded dried oleander plants

Treatment & Prognosis

• Perform gastric decontamination (activated charcoal administration, gastric lavage if appropriate) for recent ingestion
• Provide supportive care including electrolyte imbalance correction and cardiac arrhythmia management
• Monitor cardiac function continuously until symptoms resolve, administer anti-arrhythmic medication as required

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Professional Toxicology

Scientific NameNerium oleander

AliasesRose-Bay

Toxicity Grade

HumansSevere

CatsSevere

DogsSevere

HorsesSevere

Target Organs

HeartGastrointestinal tractNervous system

Mechanism of Action

• Cardiac glycosides inhibit sodium-potassium ATPase in cardiac cells, leading to abnormal cardiac contractility and rhythm

• Toxic compounds irritate gastrointestinal mucosa, causing gastrointestinal damage and related symptoms

Other Species Risk (CliniTox)

Information from CliniTox veterinary text.

Birds (ducks, swans): Extremely sensitive to oleander poisoning, ingestion of dried oleander leaves can cause rapid death

Cattle: Poisoning symptoms include restlessness, weakness, bradycardia, arrhythmia, colic, muscle tremors

Guinea pigs: Multiple cases of oleander poisoning in guinea pigs have been reported

Confusion Risk

The following plants look similar and may be confused:

Yellow oleander Thevetia peruviana

Both belong to the Apocynaceae family and have similar leaf and flower appearance, both are extremely toxic; the key difference is that Thevetia peruviana produces triangular drupe fruits, while oleander produces long narrow follicle fruits

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Related Toxic Plants

Madagascar periwinkle

Catharanthus roseus

Moderate

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Data Sources

1. ASPCA Animal Poison Control

2. CliniTox (Universität Zürich)

This information is for reference only and does not constitute medical advice. If ingestion or poisoning is suspected, seek medical or veterinary attention immediately.