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Melatonin Receptor Agonist

Melatonin

Brand names: Circadin (2 mg PR), Slenyto (paediatric)

Melatonin is a hormone used as a short-term treatment for insomnia (especially in adults over 55), for jet lag, and under specialist guidance for sleep problems in some children with neurodevelopmental conditions.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

DIRECTIONS Take 15 minutes before meals Adults : 20 drops in a little water, 2 times per day

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2018-12-22. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It is the natural sleep-regulating hormone; supplementing it helps reset or reinforce the sleep-wake cycle.

Prescribing in practice

  • It is generally used short-term for primary insomnia; address sleep hygiene and underlying causes.
  • Next-day drowsiness can occur; modified-release brands are not interchangeable.
  • It is metabolised by CYP1A2, so smoking and some drugs (e.g. fluvoxamine) alter levels.

Monitoring

Review sleep benefit and the ongoing need.

Counselling the patient

  • Take it a short time before bed as directed.
  • It can cause next-day drowsiness — take care driving.
  • Continue good sleep habits.

Evidence & guidelines

A short-term option for insomnia (notably in adults over 55) and used under specialist guidance for sleep problems in some children with neurodevelopmental conditions.

Reference: NICE TA739 (Slenyto); MHRA SPC Circadin; Herxheimer & Petrie Cochrane Review 2002 (jet lag); ESC/ERS Sleep Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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