Introduction to poisoning from plants

Significant poisoning from a plant ingestion is rare. In most plant ingestions, the patient remains asymptomatic or develops minor gastrointestinal effects. Investigations are rarely required and management is primarily supportive care; generally patients who appear well and are asymptomatic after their exposure can be discharged. If concerned, contact a poisons information centre (13 11 26).

Accidental exposures to plants by young children are fairly common, but the dose ingested is usually low (eg one or two berries of a minimally toxic or nontoxic plant) and the child can be observed at home to see if symptoms develop.

Deliberate ingestion of a toxic plant, for a psychoactive response or self-harm, can be life threatening and require emergency management. Hospital admission may be warranted for observation, supportive care, decontamination, specific drug therapy (including antidotes) and critical care management. If deliberate ingestion of a toxic plant is suspected, seek advice from a clinical toxicologist or poisons information centre. All patients who present with deliberate self-poisoning from plants require psychiatric assessment before discharge.

Accurate identification of the plant is essential when assessing the risk of an exposure and need for management. Contact a poisons information centre; they may be able access plant identification specialists at a herbarium, botanic garden or nursery. Images of a wide range of potentially poisonous plants can be found on the Queensland Poisons Information Centre website.

In addition to identifying the plant species implicated, the risk assessment should also include the following factors that influence toxicity:

• estimated dose ingested—it is difficult to predict the effects of a plant exposure based on the estimated dose ingested because of the variable concentration of toxins in different plant parts, as well as geographical and seasonal variation
• plant form ingested—tea brewed from the flowers of the anticholinergic Brugmansia species (angel’s trumpet) is likely to be highly toxic and have a rapid onset of effects, whereas ingesting other parts of the same plant may result in minimal toxicity. Ingestion of seeds, particularly from Datura stramonium (jimsonweed, common thorn apple), can result in prolonged release of the toxin, and patients may require admission for 1 to 2 days or longer. Cooking may or may not affect the toxin’s action
• route of exposure—physical contact with plant material can cause irritation or an allergic reaction of the skin or eyes; inhalation of pollen or perfume can cause respiratory symptoms
• timing of exposure
• clinical presentation.

Common plant-derived toxins are listed in Common plant-derived toxins; see individual plant poisoning monographs for clinical presentation and management.