thoughtscape NP Psychiatry · Patient education
Tasimelteon
Hetlioz • a medicine for specific sleep-clock disorders
Helps the brain's sleep clock follow a more regular rhythm. Timing and daily consistency matter; benefit may take time.
Draft for review · Clinical content has not been revalidated for this website.
MT1 and MT2 respond to melatonin, a natural timing signal. The diagram does not assign a separate proven benefit to each receptor.
What it is used for
Capsules treat Non-24 sleep-wake disorder in adults, when the sleep clock drifts out of step with the day.
They also treat nighttime sleep problems in Smith-Magenis syndrome from age 16. A separate liquid is used for younger children with that syndrome.
How it works
Tasimelteon acts on two melatonin receptors involved in the body's sleep-wake timing.
It is not a general sleeping pill for every kind of insomnia. It helps manage the sleep problem; it does not cure the underlying condition.
What to expect over time
EACH NIGHT
Take it at the same time, one hour before bed, without food.
WEEKS TO MONTHS
Non-24 may improve gradually as the sleep clock aligns.
ONGOING
Keep a sleep diary and review daytime function with your team.
Taking your medication
Take only the prescribed dose. Swallow capsules whole; do not open, crush, or chew them. Do not raise the dose because you are not sleepy right away.
If you cannot take it near your usual time, skip that night's dose. Take the next dose at the regular time. Never double up.
After taking it, limit activity to getting ready for bed. Avoid alcohol and check before adding any sleep medicine or supplement.
When to get help
Call 911: severe breathing trouble, inability to wake, collapse, or swelling of the mouth or throat.
Call promptly: marked daytime sleepiness, falls or new unsafe behavior. Do not drive if you are sleepy or impaired.
Too much medicine? Call Poison Control at 1-800-222-1222 immediately. Do not wait for symptoms.
Early side effects
Headache, nightmares, or unusual dreams, and sleepiness can occur. Tell your team if these are severe or do not settle; a different plan may be needed.
Other effects to discuss
Liver blood-test changes and respiratory or urinary infections were reported in studies. Tell your team about fever, persistent cough, or painful/frequent urination. These symptoms need assessment, not a guess about the cause.
What to keep track of
Keep track of sleep, naps, and daytime alertness. Do not drive or use dangerous equipment until you know how this medicine affects you and are fully alert. A short time in the body does not guarantee a clear head the next morning.
Before you start
Tell your team about liver disease, allergies, other sleep problems, falls, pregnancy or breastfeeding. Discuss driving, early shifts, and overnight caregiving. Bring a list of prescriptions, OTC medicines, and supplements, and mention cigarette smoking or a recent change in smoking.
Medicines & interactions
Fluvoxamine and similar medicines
Some medicines sharply raise tasimelteon levels. Fluvoxamine should not be combined with it; ask a pharmacist to check the full list.
Rifampin and other enzyme inducers
These can make treatment much less effective. Do not try to compensate with extra tasimelteon.
Bedtime beta-blockers
Medicines such as metoprolol may reduce its benefit when taken at night. Ask about timing; do not stop or move a heart medicine yourself.
Alcohol, sedatives, and supplements
Alcohol can worsen impairment. Check other sleep aids, melatonin, anxiety medicines, and sedating allergy products before combining them.
Everyday tips
Keep your agreed bedtime and wake-up routine.
Use an accessible reminder for the nightly dose.
Record daytime naps as well as nighttime sleep.
Ask your team before changing the timing for travel.
Your questions, answered
Can I stop once sleep improves?
Talk with your prescriber first. A taper is usually unnecessary, but continued treatment may be needed to keep your sleep clock aligned. Sleep problems can return after stopping.
Is it the same as melatonin?
No. It uses related receptors but is a different prescription medicine with its own dose and interactions. Do not substitute or add melatonin without checking.
What about the liquid for children?
Hetlioz LQ is a different, weight-dosed product for Smith-Magenis syndrome at ages 3–15. Do not substitute capsules. Follow its separate instructions, shake at least 30 seconds, and measure with the supplied oral syringe.
What about pregnancy or breastfeeding?
Information is limited. Discuss benefits and possible risks with your prescriber before starting, and contact them if pregnancy occurs. Do not assume a medicine that acts like melatonin is risk-free.
Storage & safety
Keep capsules in their closed container at room temperature, away from light and moisture. Store securely, away from children and pets. LQ needs refrigeration and its own after-opening discard date; ask the pharmacist to mark it. Never share medicine.
About this information
For general information only; not a substitute for individualized medical advice. This sheet does not cover every risk or interaction. Ask your prescriber or pharmacist before changing how you take this medication.
Sources
Educational inclusion does not mean this medication or its indications are treated at this practice. Review the guide for your exact product with your prescriber or pharmacist.