9.2 Oxalate, Irritant, Hallucinogenic, and Stimulant Plants
Key Takeaways
- Insoluble calcium oxalate plants such as dieffenbachia and philodendron cause immediate oral pain, drooling, and swelling that is almost always self-limited, while soluble oxalate plants such as rhubarb leaves can cause systemic hypocalcemia and kidney injury in large ingestions.
- Toxalbumin plants are the dangerous gastrointestinal group: castor bean (ricin) and rosary pea (abrin) inhibit ribosomal protein synthesis and can be lethal if the seed coat is chewed, whereas an intact swallowed seed usually passes harmlessly.
- Pokeweed causes prolonged vomiting and diarrhea from saponins, and improperly prepared young shoots are a recurring cause of foraging outbreaks.
- Hallucinogenic plant exposures include morning glory seeds (lysergic acid amides), nutmeg (myristicin, with a 3 to 8 hour delay), Salvia divinorum (kappa opioid agonism), and peyote (mescaline), all managed with reassurance and benzodiazepines rather than antipsychotics.
- Most pediatric plant exposures produce no effect or minor gastrointestinal upset, so triage focuses on identifying the small set of plants with cardiac, hepatic, convulsant, or protein-synthesis toxicity.
Last updated: September 2026
Plant calls follow a predictable pattern: a toddler put a leaf or berry in the mouth, the caller is frightened, and the exposure is almost always minor. The specialist's task is to identify the plant, then decide whether it belongs to one of the small groups that cause real harm.
Oxalate-Containing Plants
Insoluble Calcium Oxalate (the common houseplants)
Dieffenbachia (dumb cane), Philodendron, Epipremnum (pothos), Spathiphyllum (peace lily), Colocasia (elephant ear), Anthurium, Caladium, and Arisaema (jack-in-the-pulpit) contain needle-shaped calcium oxalate crystals packaged in specialized cells that fire on chewing.
- Immediate oral and pharyngeal burning, drooling, lip and tongue swelling, and refusal to eat or drink. Voice change occurs occasionally.
- Because the crystals are insoluble, there is no systemic oxalate absorption, so hypocalcemia and kidney injury do not occur.
- Management: rinse the mouth, offer cold liquids, ice pops, or ice chips, and consider an oral analgesic. Most children are managed at home. Refer if there is drooling with airway compromise, stridor, inability to swallow, or significant swelling.
Soluble Oxalates
Rhubarb leaves (the stalk is edible), Oxalis species in large amounts, and star fruit (carambola) contain soluble oxalate salts that are absorbed.
- Large ingestions bind serum calcium: paresthesias, tetany, QT prolongation, and dysrhythmias, plus calcium oxalate crystalluria and acute kidney injury.
- Star fruit also contains caramboxin, a neurotoxin that accumulates in patients with chronic kidney disease and causes hiccups, vomiting, confusion, and seizures; those patients should avoid it entirely.
- Management: ionized calcium, electrolytes, kidney function, fluids, and intravenous calcium for symptomatic hypocalcemia.
Gastrointestinal Irritants and Toxalbumins
Toxalbumins (lectins)
| Plant | Toxin | Key Facts |
|---|---|---|
| Castor bean (Ricinus communis) | Ricin | Inhibits ribosomal protein synthesis by depurinating 28S ribosomal RNA. An intact swallowed seed usually passes harmlessly, but a chewed seed releases toxin: severe hemorrhagic gastroenteritis in hours, then hypovolemic shock, hepatic and kidney injury, and death. Management is aggressive fluid resuscitation and supportive care; no antidote exists |
| Rosary pea, jequirity bean (Abrus precatorius) | Abrin | Same mechanism, even more potent by weight. Hard glossy red seeds with a black spot, used in jewelry; injury requires the seed coat to be broken |
| Black locust (Robinia pseudoacacia) | Robin | Vomiting, diarrhea, weakness |
| Wisteria | Lectin and glycoside | Persistent vomiting and diarrhea; seeds and pods |
Saponin and Other Irritant Plants
| Plant | Clinical Effect |
|---|---|
| Pokeweed (Phytolacca americana) | Saponins cause burning mouth, prolonged and forceful vomiting and diarrhea, cramping, and occasionally hypotension. Young shoots are eaten as "poke salad" after repeated boiling with water changes; toxicity follows improper preparation. The root is the most toxic part |
| Holly, pyracantha, cotoneaster, mountain ash berries | Mild gastrointestinal upset; classic reassurance calls |
| Daffodil, hyacinth, tulip bulbs | Lycorine and related alkaloids: vomiting and diarrhea, often after bulbs are mistaken for onions |
| Iris, buttercup, daphne, privet | Local irritation and gastroenteritis |
| Mistletoe (American) | Gastrointestinal upset; the feared cardiotoxicity is largely a myth for the American species |
| Poinsettia | Essentially nontoxic: mild dermal or oral irritation only. Correcting this myth is a routine poison center function |
| Azalea, rhododendron (Rhododendron species) | Grayanotoxins bind sodium channels: vomiting, bradycardia, hypotension, and atrioventricular block. "Mad honey" made from rhododendron nectar causes the same picture; treat with atropine and fluids |
Hallucinogenic and Stimulant Plants
| Plant | Active Principle | Presentation | Management |
|---|---|---|---|
| Morning glory seeds (Ipomoea), Hawaiian baby woodrose (Argyreia nervosa) | Lysergic acid amides | Visual distortion, nausea and vomiting, mydriasis, tachycardia, anxiety; several hundred seeds are typically chewed | Quiet environment, benzodiazepines |
| Nutmeg (Myristica fragrans) | Myristicin, elemicin | Delayed 3 to 8 hours: agitation, hallucinations, dry mouth, flushing, tachycardia, and a sense of impending doom lasting up to 24 to 48 hours. Requires tablespoon quantities | Supportive care, benzodiazepines, reassurance |
| Salvia divinorum | Salvinorin A, a potent kappa opioid agonist | Brief but intense dissociation, altered perception of body and time, lasting minutes when smoked | Reassurance; naloxone is not useful |
| Peyote (Lophophora williamsii), San Pedro cactus | Mescaline | Prolonged hallucinations (8 to 12 hours) with prominent nausea and vomiting, mydriasis, tachycardia | Supportive care |
| Ayahuasca (Banisteriopsis caapi plus DMT-containing plants) | Dimethyltryptamine with harmala monoamine oxidase inhibitors | Vomiting, hallucinations; the MAO inhibition creates a real risk of serotonin toxicity or hypertensive reactions with co-ingested serotonergic drugs or tyramine | Benzodiazepines; assess for serotonin toxicity |
| Kava (Piper methysticum) | Kavalactones | Sedation, ataxia; hepatotoxicity with chronic use | Supportive |
| Khat (Catha edulis) | Cathinone | Sympathomimetic stimulation: euphoria, hypertension, tachycardia, insomnia | Benzodiazepines |
| Betel nut (Areca catechu) | Arecoline, a muscarinic agonist | Salivation, lacrimation, bronchospasm, bradycardia, plus stimulation; chronic use causes oral cancer | Atropine if severe cholinergic features |
| Ephedra (Ephedra sinica, ma huang) | Ephedrine alkaloids | Hypertension, dysrhythmias, stroke | Benzodiazepines, avoid unopposed beta-blockade |
| Tobacco plant and "green tobacco" (Nicotiana) | Nicotine | Biphasic nicotinic toxicity; covered with nicotine products | Supportive, atropine for secretions |
Antipsychotic caution: for plant hallucinogen exposures, benzodiazepines are preferred. Antipsychotics add antimuscarinic burden, impair heat dissipation, and lower the seizure threshold, which is dangerous when the actual plant may be an anticholinergic species such as jimson weed.
Dermatologic Plant Exposures
| Plant | Reaction |
|---|---|
| Poison ivy, oak, sumac (urushiol) | Delayed type IV allergic contact dermatitis; wash within minutes, topical steroids, oral steroids for severe or facial involvement |
| Giant hogweed, wild parsnip, lime and celery (furocoumarins) | Phytophotodermatitis: sun-activated burn-like blistering with residual hyperpigmentation; wash and protect from sunlight |
| Stinging nettle | Histamine and formic acid: immediate urticaria |
| Prickly pear, cactus spines, agave | Mechanical injury and irritant dermatitis |
Identification-First Triage
- Get a name or a picture. Ask for the plant tag, a photograph, or a description of leaf shape, flower, berry color, and whether sap is milky. Involve a local extension service or botanist when needed.
- Ask what part and how much. Roots, seeds, and bulbs concentrate toxin; a single berry is rarely the problem, and chewing matters more than swallowing for hard seeds.
- Screen for the dangerous groups: cardiac glycosides, anticholinergics, convulsants such as water hemlock, nicotinic plants such as poison hemlock, sodium channel agents such as aconite and yew, and toxalbumins such as castor bean.
- Expect minor effects otherwise. Dilute with liquids, control vomiting, and schedule follow-up calls.
- Refer any symptomatic patient, any foraged-meal exposure, any intentional ingestion, and any exposure with airway symptoms.
Test Your Knowledge
A 2-year-old bites a leaf of a houseplant and immediately screams, drools, and has a swollen lower lip. The plant is identified as a dieffenbachia. What is the expected course and management?
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Test Your Knowledge
A 30-year-old chewed and swallowed several castor bean seeds from a decorative necklace. Six hours later he has severe vomiting, bloody diarrhea, and hypotension. Which statement is accurate?
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Test Your Knowledge
A 17-year-old ate several tablespoons of ground nutmeg on a dare and calls 6 hours later with agitation, visual distortions, dry mouth, flushing, and a heart rate of 115. Which statement fits this exposure best?
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