Plant Poisoning
M. Michele Mariscalco
Plants are among the most common category of accidental ingestions reported by poison centers. In the United States, plant ingestions account for 10% of all calls. In the industrialized world, most ingestions involve house and garden plants, only a small fraction of which pose a serious toxic threat. Most pediatric cases involve either “nibbling events,” which rarely produce more than temporary discomfort, or exposure to nontoxic house plants. However, significant morbidity and mortality have occurred in children who have ingested plant substances that were stored in the home for other than decorative purposes. Such cases frequently involve hallucinogenic plants and mushrooms, products made from plants than contain belladonna alkaloids (jimson weed), or teas and other concoctions produced for “herbal highs” (morning glory seeds, wild lettuce, yohimbine, catnip).
Proper identification of the plant that the child has ingested is crucial for effective therapy and management; however, identification may be problematic, especially over the telephone. Relatives or friends can bring in specimens of the consumed plant when questions exist about the identity of the plant. However, identification may remain difficult without familiarity of poisonous and nonpoisonous plants in a particular locale.
INITIAL MANAGEMENT OF POISONING
As outlined in previous chapters, syrup of ipecac is no longer recommended for use at home by the American Academy of Pediatrics. In addition, emesis may be hazardous when large amounts of leafy plant products have been ingested, owing to possible glottic obstruction. Dilution is also not routinely recommended after ingestion of a medication. However, dilution by having the child drink 100 to 200 mL of water or another drink is a routine recommendation for the ingestion of a nonpharmaceutical agent. It is unclear whether this recommendation should be routinely followed in plant poisoning. Referral to the local poison control center may be helpful in making the determination of potential toxicity. Parents should be reminded to have the number of the poison control center easily accessible. As with any ingestion, symptomatic cases or those with toxic potential should be referred to the emergency department.
On presentation to the emergency department, the child should be evaluated and treatment begun unless the plant can be identified and is known to be nontoxic. The use of activated charcoal may be indicated because many of the toxins delay gastric absorption. Because the use of multiple oral doses of activated charcoal in plant ingestions has not been studied sufficiently, this approach cannot be routinely recommended. The child should be observed for a short period. If the plant is identified and is thought to be nontoxic or if it cannot be recognized and the child remains asymptomatic, the child may be discharged. If the child ingested a potentially toxic species or is symptomatic, he or she should be admitted for further observation and supportive treatment. Plant poisonings may be complex and not well delineated in the existing literature, and multisystem problems should be anticipated, even though the plant may be in a specific toxin category.
PLANT TOXINS
Most of the symptomatic plant poisonings in the United States are from a large heterogenous group that causes gastrointestinal irritation. The following is a description of the most common plant toxins, along with clinical manifestations of poisoning and recommended therapies.
Calcium Oxalate Crystals
Philodendron and dieffenbachia are the most common plant exposures in developed countries. Elephant ear plants are the most common plant exposures in other less developed countries. These three plants belong to the Araceae family, which contains more than 1,800 known species. These family members contain calcium oxalate crystals, which, when the plant is chewed, are ejected from specialized explosive “ejector cells.” These crystals then become lodged in the lining of the mouth, tonge, and throat and thus lead to local inflammatory reactions, which include burning, irritation, edema of the buccal cavity, hypersalivation, and aphonia. Chewing of the leaves cause minor mouth and throat burning. However, ingestion of the leaves from these plants can result occasionally in severe oropharyngeal injury with airway compromise. There is no indication for the use of antibiotics, atropine, or antihistamines. Antacids as demulcents and neutralizing agents have been recommended.
Toxins Causing Severe Gastoenteritis
Severe vomiting, colicky abdominal pain, and diarrhea can result from ingestion of pokeweed roots and stems, wisteria seeds, buttercup leaves, daffodil bulbs, and seeds and pods from the bird of paradise. Twenty to 30 of the bright red or black berries of the holly tree are estimated to be a fatal dose for a small child. Holly contains ilicin and several unidentified toxins that cause diarrhea, vomiting, nausea, and abdominal pains. Boxwood contains a toxic alkaloid that can cause severe gastroenteritis if a moderate quantity of leaves is eaten.
The rosary pea (i.e., jequirty bean or Indian bean) and castor beans are attractive seeds and are used extensively in inexpensive beadwork and jewelry. They contain a toxalbumin that is released when chewed, causing violent hemorrhagic gastroenteritis that leads to profound dehydration and circulatory collapse. Therapy consists of fluid and electrolyte management. Alkalinization of the urine with sodium bicarbonate may prevent precipitation of hemoglobin and its products in the kidney tubules.
Cardiac Glycosides
The leaves of common foxglove, oleander, and lily of the valley and the berries of mistletoe contain cardiac glycosides. Soon after ingestion, the child may complain of mouth irritation, vomiting, and diarrhea. As the digitalis is absorbed, acute digitalis effects ensue as evidenced by bradycardia with progressive heart block and hyperkalemia. A randomized control trial in Sri Lanka demonstrated that the use of digoxin-specific Fab antibody was highly effective in treating oleander-induced dysrhythmias and electrolyte disturbances. Anecdotal reports indicate that digoxin-specific Fab antibody may be efficacious in reversing acute effects with other cardiac glycoside–containing plants. Mistletoe also contains sympathomimetic agents that may cause seizures and hypertension.
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