Section 10 · Monograph
Tasimelteon
Reviewed Nov 2026FDA label
HetliozMelatonin receptor agonist
- Forms
- Cap: 20mg
- Dose
- 20mg 1h before bedtime, same time nightly (Non-24-hour sleep-wake disorder)
- MOA
- MT1/MT2 receptor agonism
Indications
- Non-24-hour sleep-wake disorder in adultsFDA-labeled
- Nighttime sleep disturbances in Smith-Magenis syndrome (pediatric oral suspension)FDA-labeled
Mechanism of Action
- Melatonin MT1 and MT2 receptor agonist that entrains the circadian rhythm
Full Dosing
Adult / usual
- Non-24: 20mg capsule one hour before bedtime at the same time every night, with or without food (be consistent)
- Smith-Magenis syndrome: weight-based oral suspension per label
- Benefit may take weeks to months; keep a sleep log
Contraindications
- None listed in labeling
Drug Interactions
- Strong CYP1A2 inhibitors (fluvoxamine): avoid
- Strong CYP3A4 inducers (rifampin): avoid
- Beta-blockers may reduce endogenous melatonin effect
Adverse Effects
- Headache and elevated ALT
- Nightmares or unusual dreams
- Upper respiratory infection and urinary tract infection
- Somnolence
Monitoring Parameters
- Sleep-wake pattern and sleep logs
- Liver enzymes if clinically indicated
Pregnancy & Lactation
- Limited human data; use only if benefit justifies risk