Acute metaldehyde poisoning from ingestion: clinical features and implications for early treatment

To describe and compare the clinical features of patients with acute metaldehyde toxicity from suicidal and accidental ingestion of metaldehyde, and to elucidate factors influencing early treatment and disposition.

We undertook a systematic review and retrospective analysis of the clinical characteristics and outcomes of patients with acute toxicity from ingesting metaldehyde.

Twenty-one cases identified between 1965 and 2021 were analyzed. The median age was 32 years (range, 3-68 years), and two-thirds of patients experienced symptoms (14/21, 67%). In symptomatic patients, gastrointestinal symptoms were present in two-thirds (9/14, 64%), and half experienced neurologic complications (8/14, 57%); of those with neurologic complications, half experienced seizures (8/14, 57%). There were near-equal cases of accidental and suicidal poisoning. Those who attempted suicide were likelier to develop symptoms (90% versus 45%, P = 0.031), experience seizures (60% versus 18%, P = 0.049), require intensive care (50% versus 9%, P = 0.038), and suffer longer hospitalizations (13.3 days versus 2.9 days, P = 0.005), despite no statistically significant differences in the doses of metaldehyde consumed when compared against patients with accidental ingestion (9.04 g versus 2.03 g, P = 0.09).

The circumstances in which metaldehyde is consumed heavily influence clinical symptoms and outcomes. Early and close observation for seizures and adopting a lowered threshold for escalation to the intensive care unit are recommended in patients attempting suicide even when the dose ingested cannot be determined at that time, which is common during the early phases of treatment.