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Welcome to HETLIOZ® (tasimelteon)

The first and only FDA-approved treatment for Non-24-Hour Sleep-Wake Disorder (Non-24).

The first and only FDA-approved treatment for nighttime sleep disturbances in Smith-Magenis Syndrome (SMS).

HetliozSolutions™ is here to help. Sign up by calling 1-844-HETLIOZ. That's 1-844-438-5469, Monday through Friday, 9AM to 8PM, Eastern Standard Time. Learn more about HETLIOZSolutions.


HETLIOZ® is the first and only medication that's been proven to treat people with Non-24 and nighttime sleep disturbances in SMS.

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HETLIOZSolutions™ can help with questions about insurance coverage and prescription delivery, as well as provide educational resources.

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Here's Important Safety Information for
HETLIOZ® (tasimelteon).


HETLIOZ® (HeT-lee-ōz) [tasimelteon] capsules are indicated for the treatment of:

  • Non-24-Hour Sleep-Wake Disorder (Non-24) in adults
  • Nighttime sleep disturbances in Smith-Magenis Syndrome (SMS) patients 16 years of age and older.

HETLIOZ LQ® (HeT-lee-oz el-Cue) oral suspension is indicated for:

  • Nighttime sleep disturbances in SMS in pediatric patients 3 to 15 years of age.

Important Safety Information

HETLIOZ® may cause drowsiness. After taking HETLIOZ®, limit your activity to preparing for bed. HETLIOZ® can potentially impair your ability to perform activities that require complete mental alertness.

The most common side effects associated with HETLIOZ® include headache, elevated liver enzymes (ALT), nightmares or abnormal dreams, and upper respiratory or urinary tract infection. These side effects may occur more frequently in patients 65 years of age or older. Adverse reactions were similar in patients treated for (Non-24) and patients with SMS treated for nighttime sleep disturbances. Adverse reactions were also similar in pediatric patients (3 years to 15 years) who received HETLIOZ LQ® oral suspension, and patients ≥16 years of age who received HETLIOZ® capsules.

Tell your healthcare provider about all of the medicines you're taking. HETLIOZ® should not be taken in combination with fluvoxamine or rifampin.

Tell your healthcare provider about all of your health conditions, including whether you are pregnant, are planning to become pregnant, or are breastfeeding. HETLIOZ® has not been studied in pregnant women.

The safety and effectiveness of HETLIOZ® for the treatment of Non-24-Hour in children have not been established. The safety and effectiveness of HETLIOZ LQ® oral suspension for the treatment of nighttime sleep disturbances in SMS have been established in pediatric patients 3 years and older.

HETLIOZ® is not recommended for use in patients with severe liver problems.

Consumer Important Safety Information

You are encouraged to report side effects of prescription drugs to the FDA. To report side effects, contact Vanda Pharmaceuticals Inc. at 1-844-438-5469 or or FDA at 1-800-FDA-0178 or

For more information, ask your healthcare provider or call 1-844-HETLIOZ (1-844-438-5469).

This information does not take the place of talking with your healthcare provider for medical advice about your condition or treatment.

Download an accessible PDF or listen to the full US Prescribing Information. You can also hear the full US Prescribing Information by calling 1-844-HETLIOZ (1-844-438-5469).