Tasimelteon: uses, dosing, side effects & brands
Tasimelteon is a melatonin receptor agonist sold in the U.S. under 2 brand and generic names, for circadian rhythm sleep disorders. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Melatonin Receptor Agonist
- Treats (across its forms)
- Circadian Rhythm Sleep Disorders
- Available as
- Capsule · Suspension
- Sold as
- 2 products — Hetlioz and Hetlioz Lq
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
- What the pharmacy pays
- about $11351 for a 30-count supply — not your price
How Hetlioz is dosed
From the FDA label for Hetlioz (application NDA205677). Other tasimelteon products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
Indicated Population Dosage Form Body Weight Recommended Dosage Non-24 ( 2.2 ) Adults Capsules Not applicable 20 mg one hour prior to bedtime Nighttime sleep disturbances in SMS ( 2.3 ) Patients 16 years of age and older Capsules Not applicable 20 mg one hour prior to bedtime Pediatric Patients 3 to 15 years of age Oral Suspension ≤ 28 kg 0.7 mg/kg one hour before bedtime ≥ 28 kg 20 mg one hour prior to bedtime HETLIOZ capsules and HETLIOZ LQ oral suspension are not substitutable ( 2.1 ) Administer at the same time every night ( 2.2 , 2.3 ) Take without food ( 2.4 ) 2.1 Non-Interchangeability between HETLIOZ Capsules and HETLIOZ LQ Oral Suspension HETLIOZ capsules and HETLIOZ LQ oral suspension are not substitutable [see Clinical Pharmacology ( 12.3 )]. 2.2 Recommended Dosage for HETLIOZ Capsules for Non-24 Adults The recommended dosage of HETLIOZ capsules in adults is 20 mg one hour before bedtime, at the same time every night. Because of individual differences in circadian rhythms, drug effect may not occur for weeks or months. 2.3 Recommended Dosage for HETLIOZ Capsules and HETLIOZ LQ Oral Suspension for Nighttime Sleep Disturbances in SMS Patients 16 years of Age and Older The recommended dosage of HETLIOZ capsules in patients 16 years and older is 20 mg one hour before bedtime, at the same time every night. Pediatric Patients 3 Years to 15 Years of Age The recommended…
Everything below is the FDA label for Hetlioz (capsule). Tasimelteon is also sold as suspension, and those are different medicines to take — follow the label for the one you were prescribed.
Hetlioz side effects
The most common adverse reactions (incidence >5% and at least twice as high on HETLIOZ than on placebo) were headache, increased alanine aminotransferase, nightmares or unusual dreams, and upper respiratory or urinary tract infection ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Vanda Pharmaceuticals Inc. at 1-844-438-5469 or www.hetlioz.com or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. More than 2080 subjects have been treated with at least one dose of HETLIOZ, of which more than 380 have been treated for > 26 weeks and more than 170 have been treated for > 1 year. Non-24-Hour Sleep-Wake Disorder (Non-24) A 26-week, parallel-arm placebo-controlled study (Study 1) evaluated HETLIOZ (n=42) compared to placebo (n=42) in patients with Non-24. A randomized-withdrawal, placebo- controlled study of 8 weeks duration (Study 2) also evaluated HETLIOZ (n=10), compared to placebo (n=10), in patients with Non-24. In placebo-controlled studies, 6% of patients exposed to HETLIOZ discontinued treatment due to an adverse event, compared with 4% of patients who received placebo.…
Who shouldn’t take Hetlioz
None. None ( 4 )
Hetlioz drug interactions
Strong CYP1A2 inhibitors (e.g., fluvoxamine): Avoid use of HETLIOZ in combination with strong CYP1A2 inhibitors because of increased exposure ( 7.1 , 12.3 ) Strong CYP3A4 inducers (e.g., rifampin): Avoid use of HETLIOZ in combination with rifampin or other CYP3A4 inducers, because of decreased exposure ( 7.2 , 12.3 ) 7.1 Strong CYP1A2 Inhibitors (e.g., fluvoxamine) Avoid use of HETLIOZ in combination with fluvoxamine or other strong CYP1A2 inhibitors because of a potentially large increase in tasimelteon exposure and greater risk of adverse reactions [see Clinical Pharmacology ( 12.3 )]. 7.2 Strong CYP3A4 Inducers (e.g., rifampin) Avoid use of HETLIOZ in combination with rifampin or other CYP3A4 inducers because of a potentially large decrease in tasimelteon exposure with reduced efficacy [see Clinical Pharmacology ( 12.3 )]. 7.3 Beta-adrenergic Receptor Antagonists (e.g., acebutolol, metoprolol) Beta-adrenergic receptor antagonists have been shown to reduce the production of melatonin via specific inhibition of beta-1 adrenergic receptors. Nighttime administration of beta-adrenergic receptor antagonists may reduce the efficacy of HETLIOZ.
Every tasimelteon product we track (2)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
| # | Drug | Rating | Type | Form | Generic? | Pharmacy pays | |
|---|---|---|---|---|---|---|---|
| 1 | Not yet rated | Prescription | Capsule | Generic | $11351 | View → | |
| 2 | Not yet rated | Prescription | Suspension | Generic | $11351 | View → |
What tasimelteon pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
| Imprint | Strength | Colour | Shape | Maker |
|---|---|---|---|---|
| APO;TAS;20 | 20 mg | blue, blue | capsule | — |
| A44 | 20 mg | blue | capsule | — |
| 20;mg;MT1 | 20 mg | blue | capsule | — |
| VANDA;20;mg | 20 mg | blue | capsule | — |
How long tasimelteon keeps
The date on a sealed pack is not the only one: some tasimelteon labels start a second clock once the product is opened or mixed, as short as 5 weeks.
Does tasimelteon expire? The in-use limits and storage rules from its labelsWhat people report to the FDA about tasimelteon
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 21 reports naming tasimelteon, and the FDA flagged 48% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- aortic valve disease2 reports
- dyspnoea2 reports
- memory impairment2 reports
- streptococcal infection2 reports
- abortion spontaneous1 reports
- adverse event1 reports
- amnesia1 reports
- anxiety1 reports
Read these as a signal, not a rate. A report does not mean tasimelteon caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved August 26, 2026.
Related calculators
Frequently asked questions
What is Hetlioz?
Hetlioz (Tasimelteon) is a melatonin receptor agonist used to treat Circadian Rhythm Sleep Disorders.
What kind of drug is tasimelteon?
The FDA classifies tasimelteon as a melatonin receptor agonist. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take tasimelteon with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run tasimelteon against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is tasimelteon sold under?
We track 2 tasimelteon-containing products in the U.S.: Hetlioz and Hetlioz Lq. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does tasimelteon come in?
Across the brands we track, tasimelteon is currently marketed as capsule and suspension, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic tasimelteon?
We do not currently list a generic-labelled tasimelteon product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Tasimelteon: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/tasimelteon
- MLA
- “Tasimelteon: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/tasimelteon.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for tasimelteon on DailyMed (NIH) ↗.