Case
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Intentional ingestion of 450 mg melatonin by an adolescent: somnolence and persistent suicidal ideation
What it means for practice
Adolescents require formal psychiatric evaluation after intentional melatonin ingestion, regardless of the severity of physical findings. Low physiological toxicity does not indicate low suicide risk.
Summary
A 16-year-old female intentionally ingested 450 mg of melatonin (90 × 5 mg tablets). The authors also considered this case alongside published reports, cohort data, and evidence on melatonin toxicokinetics.
Clinical course and investigations
She presented 2.5 h after ingestion with marked somnolence: her Glasgow Coma Scale score was 13/15 and heart rate was 62 beats/min. Venous blood gas analysis showed mild metabolic acidosis with respiratory compensation: pH 7.34 and bicarbonate 15.6 mmol/L. Mild hyponatremia and stress leukocytosis were also observed.
Hepatic, renal, and coagulation studies and a 12-lead electrocardiogram were normal. A comprehensive toxicology screen was negative, consistent with isolated melatonin exposure. The Poison Severity Score was Grade 1, Minor.
She was medically cleared within 14.5 h of ingestion. However, psychiatric evaluation identified persistent suicidal ideation, and she was transferred to inpatient psychiatric care at 20.5 h after ingestion.
Clinical lesson
The authors describe predominantly self-limited sedation and mild, transient metabolic disturbances without organ injury after massive isolated melatonin ingestion. They nevertheless emphasize that low physiological toxicity does not indicate low psychiatric risk. Every adolescent presenting after intentional ingestion of an over-the-counter chronobiotic warrants formal psychiatric evaluation, regardless of how benign the medical course appears.
Case analysis
- Likely mechanism
- The authors relate self-limited sedation after massive isolated melatonin ingestion to saturable hepatic CYP1A2-mediated clearance. The abstract does not explain the mechanism of the mild metabolic acidosis.
- Causality assessment
- Editorial WHO–UMC assessment: possible causal relationship between melatonin and somnolence. The timing is compatible with this relationship, and the negative toxicology screen supports isolated exposure; however, the abstract provides insufficient detail on resolution of individual symptoms and exclusion of all alternative causes. No author-reported causality assessment is provided.
- Take-home lesson
- A benign medical course after intentional melatonin ingestion does not exclude persistent suicide risk. Adolescents require formal psychiatric evaluation; in this case, persistent suicidal ideation prompted transfer to inpatient psychiatric care.
Source
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Miran S, Amiri B, Astaraki P, et al. Case Report: Intentional massive melatonin ingestion (450 mg) in an adolescent female. Front Toxicol. 2026;8:1958318. doi:10.3389/ftox.2026.1958318
PubMed 42960365 DOI 10.3389/ftox.2026.1958318 Original: pubmed.ncbi.nlm.nih.gov
Reviewed by: DrugCard editorial team ·
This article does not replace clinical judgement. Disclaimer
