melatonin

General information

• Primary label indications include: OTC dietary supplement (U.S.; not FDA-approved as a drug).
• Class: Adjunctive therapy
• Typical dose range: OTC products are product-dependent; many labels recommend one dose about 30 minutes before bedtime.
• Therapeutic drug monitoring not routinely recommended.
• Last reviewed: 2025-12-30

Dosing & forms

• Forms/strengths: OTC products vary widely (immediate-release vs prolonged-release; 1–10+ mg strengths). Labels often recommend a bedtime dose about 30 minutes before sleep (product-dependent).; Prescription melatonin receptor agonists (e.g., ramelteon) offer more predictable dosing and regulated manufacturing.
• Frequency: OTC products are product-dependent; many labels recommend one dose about 30 minutes before bedtime.
• Typical range: OTC products are product-dependent; many labels recommend one dose about 30 minutes before bedtime.

Mechanism (brief)

Endogenous sleep-wake hormone; MT1/MT2 receptor agonist. Widely used as an OTC dietary supplement for sleep-onset and circadian rhythm complaints.

Metabolism & Half‑life

• Metabolism: CYP1A2, CYP2C19
• Half‑life: Single-dose range 1–2 h

Therapeutic Drug Monitoring (TDM)

Recommended: No

Monitoring highlights

• Daytime sleepiness, dizziness, and next-day impairment (driving safety).
• Timing consistency and product quality (avoid stacking multiple melatonin products).
• Mood and sleep trajectories in depression or bipolar disorder.
• Reassess benefit after 1–2 weeks; discontinue if minimal benefit.

Sources

• Melatonin tablets (dietary supplement) label — DailyMed (2025)
• Melatonin (StatPearls) — StatPearls Publishing (NCBI Bookshelf) (2025)
• Meta-analysis: melatonin for the treatment of primary sleep disorders — PLoS One (PMC) (2013)
• Melatonin Natural Health Products and Supplements—presence of serotonin and variability of melatonin content — Journal of Clinical Sleep Medicine (PMC) (2017)
• Clinical Practice Guideline for the Pharmacologic Treatment of Chronic Insomnia in Adults: An American Academy of Sleep Medicine Clinical Practice Guideline — Journal of Clinical Sleep Medicine (PMC) (2017)