Merck Manual

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Plant Poisoning


Gerald F. O’Malley

, DO, Grand Strand Regional Medical Center;

Rika O’Malley

, MD, Grand Strand Medical Center

Reviewed/Revised Jun 2022 | Modified Sep 2022
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A few commonly grown plants are highly poisonous, and many plants are moderately poisonous (see table Moderately Poisonous Plants ). Few plant poisonings have specific antidotes. Most plant ingestions, including the plants listed in the aforementioned table, result in minimal symptoms unless the leaves and other components are concentrated into a paste or brewed into a tea.

Highly toxic and potentially fatal plants include the following:

  • Castor beans and jequirity beans

  • Oleander and foxglove

  • Hemlock

Castor beans and jequirity beans

Castor beans contain ricin, an extremely concentrated cellular poison. Jequirity beans contain abrin, a related and even more potent toxin. In both, the beans have a relatively impervious shell; thus, the bean must be chewed to release the toxin. However, the seed coating of the jequirity bean is often not intact, and simple bacterial digestion can release the abrin toxin.

Symptoms of either poisoning may include delayed gastroenteritis, sometimes severe and hemorrhagic, followed by delirium, seizures, coma, and death. Whole-bowel irrigation Whole-bowel irrigation Poisoning is contact with a substance that results in toxicity. Symptoms vary, but certain common syndromes may suggest particular classes of poisons. Diagnosis is primarily clinical, but for... read more should be considered because it aims to remove all beans ingested.

Oleander and foxglove

These plants and lily of the valley (which is similar but less toxic) contain digitalis glycosides. Foxglove was the original source of the drug digitalis. Toxicity includes gastroenteritis, confusion, hyperkalemia, and arrhythmias. The serum digoxin level can confirm ingestion but is not useful as quantitative information.


Hemlock poisoning (poison hemlock and water hemlock) can cause symptoms within 15 minutes.

Poison hemlock has effects on the nicotinic cholinergic receptor, beginning with dry mouth and progressing to tachycardia, tremors, diaphoresis, mydriasis, seizures, and muscle paresis. Rhabdomyolysis Rhabdomyolysis Rhabdomyolysis is a clinical syndrome involving the breakdown of skeletal muscle tissue. Symptoms and signs include muscle weakness, myalgias, and reddish-brown urine, although this triad is... read more and bradycardia may occur.


Drugs Mentioned In This Article

Drug Name Select Trade
Digitek , Lanoxicaps, Lanoxin, Lanoxin Pediatric
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NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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