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tasimelteon

Adjunctive therapy

Brands: Hetlioz, Hetlioz LQ

Last reviewed 2025-12-30

Reviewed by PsychMed Editorial Team.

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Quick answers

  • What is tasimelteon?

    Tasimelteon (brands include Hetlioz and Hetlioz LQ) is a melatonin receptor agonist indicated for treatment of Non-24-Hour Sleep-Wake Disorder (Non-24) in adults (label).

  • What is Hetlioz?

    Hetlioz is a brand name for tasimelteon (other brands: Hetlioz LQ).

  • What is Hetlioz (tasimelteon) used for?

    Label indications include: Treatment of Non-24-Hour Sleep-Wake Disorder (Non-24) in adults (label).

  • What drug class is Hetlioz (tasimelteon)?

    Melatonin receptor agonist (tasimelteon; MT1/MT2) indicated for treatment of Non-24-Hour Sleep-Wake Disorder (Non-24) in adults; requires consistent nightly dosing and may take weeks to months for effect, with clinically important CYP1A2/CYP3A4 interaction considerations.

  • What strengths does Hetlioz (tasimelteon) come in?

    Capsules: 20 mg (label).

Snapshot

  • Class: Adjunctive therapy
  • Common US brands: Hetlioz, Hetlioz LQ
  • Therapeutic drug monitoring not routinely recommended.
  • Last reviewed: 2025-12-30

Label indications

Treatment of Non-24-Hour Sleep-Wake Disorder (Non-24) in adults (label).

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Clinical Highlights

Tasimelteon (brands include Hetlioz and Hetlioz LQ) is a melatonin receptor agonist indicated for treatment of Non-24-Hour Sleep-Wake Disorder (Non-24) in adults (label). Non-24 is a circadian rhythm disorder; clinical framing emphasizes circadian entrainment over “sedation,” and symptom improvement may take weeks or months with consistent nightly dosing (label/clinical).

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  • It is not a controlled substance and generally has low misuse potential, but next-day somnolence can occur and safety planning focuses on consistent dosing and avoiding interacting medications (label/clinical).
  • Clinically important interactions include avoiding strong CYP1A2 inhibitors (e.g., fluvoxamine) and strong CYP3A4 inducers (e.g., rifampin); smoking can reduce exposure and potentially reduce efficacy (label).
  • The compare view, tasimelteon evidence feed, and tasimelteon print page help compare melatonin-pathway agents and alternative sleep strategies.

Dosing & Formulations

Capsules: 20 mg (label). Adults: 20 mg taken 1 hour before bedtime, at the same time every night; administer without food (label).

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  • If a dose is missed or cannot be taken at the usual time, the dose is skipped and the next dose is taken as scheduled (label).
  • Tasimelteon capsules and tasimelteon oral suspension are not substitutable; formulation changes require attention to non-interchangeability guidance (label).
  • Because circadian effects may take weeks or months, short trials can lead to false “nonresponse”; structured follow-up intervals and tracking sleep timing are common practical steps (clinical).

Monitoring & Risks

Somnolence, headache, and abnormal dreams can occur; next-day function and fall risk are common monitoring topics, especially with other sedatives (label/clinical). Consistency is clinically central: irregular dosing or inconsistent sleep timing can reduce benefit and complicate interpretation of response (clinical).

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  • In comorbid mood disorders, monitoring focuses on whether circadian stabilization improves mood and function versus worsening daytime sleepiness (clinical).

Drug Interactions

Avoid strong CYP1A2 inhibitors (e.g., fluvoxamine) because exposure can increase substantially (label). Avoid strong CYP3A4 inducers (e.g., rifampin) because exposure can decrease substantially and efficacy may be reduced (label).

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  • Smoking induces CYP1A2 and lowers exposure; reduced efficacy is a plausible clinical issue in smokers (label/clinical).

Practice Notes

Non-24 often benefits from collaboration with sleep medicine; diagnosis confirmation and circadian tracking (sleep logs, actigraphy when available) can clarify whether response is due to entrainment (clinical). Non-24 is most common in totally blind individuals without light perception; in sighted patients, careful differential diagnosis and circadian logging help distinguish Non-24 from delayed sleep-wake phase or irregular sleep patterns (clinical).

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  • When insomnia is driven primarily by mood episodes, substances, pain, or untreated sleep apnea, addressing those drivers is typically more impactful than adding additional hypnotics (clinical).
  • In complex polypharmacy, focusing on interaction cleanup (fluvoxamine, rifampin, other strong CYP modulators) can be a high-yield step before concluding lack of benefit (clinical).

References

  1. Tasimelteon capsules prescribing information — DailyMed (2025)
  2. Clinical Practice Guideline FOR THE Treatment OF Intrinsic Circadian Rhythm Sleep Wake Disorders: Advanced Sleep Wake Phase Disorder (aswpd), Delayed Sleep Wake Phase Disorder (dswpd), NON 24 Hour Sleep Wake Rhythm Disorder (n24swd), AND Irregular Sleep Wake Rhythm Disorder (iswrd). AN Update FOR 2015 — Journal of Clinical Sleep Medicine (2015)
  3. Tasimelteon FOR NON 24 Hour Sleep Wake Disorder IN Totally Blind People (set AND Reset): TWO Multicentre, Randomised, Double Masked, Placebo Controlled Phase 3 Trials — The Lancet (2015)
  4. Tasimelteon: A Review IN NON 24 Hour Sleep Wake Disorder IN Totally Blind Individuals — CNS Drugs (2016)
Tasimelteon (Hetlioz, Hetlioz LQ) — Summary — PsychMed