THE MERCK MANUAL: The Merck Manual of Diagnosis and Therapy
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Plant Poisoning

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A few commonly grown plants are highly poisonous, and many plants are moderately poisonous (see Table 6: Poisoning: Moderately Poisonous PlantsTables). Few plant poisonings have specific antidotes. Most plant ingestions, including the plants listed in Table Table 6: Poisoning: Moderately Poisonous PlantsTables, 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 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. Toxicity includes gastroenteritis, confusion, hyperkalemia, and arrhythmias. The serum digoxin level can confirm ingestion but is not useful as quantitative information.

K levels are closely monitored. Hyperkalemia may respond only to hemodialysis. Ca is not recommended for arrhythmias. Digoxin-specific fractionated antibody (Fab) fragments have been used to treat ventricular arrhythmias.

Hemlock

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

Poison hemlock has nicotinic effects, beginning with dry mouth and progressing to tachycardia, tremors, diaphoresis, mydriasis, seizures, and muscle paresis. Rhabdomyolysis and bradycardia may occur.

Water hemlock seems to enhance γ-aminobutyric acid (GABA) activity. Symptoms may include gastroenteritis, delirium, refractory seizures, and coma.

Table 6

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Last full review/revision February 2013 by Gerald F. O'Malley, DO; Rika O'Malley, MD

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