Last reviewed on RxList: 12/10/2020
Hetlioz Patient Information Including Side Effects

Brand Names: Hetlioz

Generic Name: tasimelteon

What is tasimelteon (Hetlioz)?

Tasimelteon is a sedative that affects substances in your body that help regulate your "sleep-wake cycle."

Tasimelteon is used to treat non-24-hour sleep-wake disorder in adults.

Tasimelteon is also used to treat nighttime sleep problems in people with a genetic disorder called Smith-Magenis Syndrome (SMS). The capsule form of tasimelteon is for people with SMS who are at least 16 years old. The oral suspension (liquid) form is for children with SMS who are from 3 to 15 years old.

Tasimelteon may also be used for purposes not listed in this medication guide.

What are the possible side effects of tasimelteon (Hetlioz)?

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • pain or burning when you urinate.

Side effects may be more likely in older adults.

Common side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What is the most important information I should know about tasimelteon (Hetlioz)?

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.


Sleep Disorders: Foods That Help Sleep or Keep You Awake See Slideshow
Hetlioz Patient Information including How Should I Take

3 pharmacies near 20147 have coupons for Hetlioz (Brand Names:Hetlioz for 20MG)

CVS Pharmacy
CVS Pharmacy

Est. Regular Price


with free coupon

View Coupon

Est. Regular Price


with free coupon

View Coupon

Est. Regular Price


with free coupon

View Coupon

What should I discuss with my healthcare provider before taking tasimelteon (Hetlioz)?

Tell your doctor if you have ever had:

Tell your doctor if you are pregnant or breastfeeding.

Do not give this medicine to a child without medical advice. Tasimelteon is approved to treat nighttime sleep problems only in children who have SMS and are at least 3 years old. Tasimelteon is not approved to treat non-24-hour sleep-wake disorder in anyone younger than 18 years old.

How should I take tasimelteon (Hetlioz)?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Take the medicine 1 hour before your normal bedtime, at the same time each night.

Take tasimelteon without food.

Swallow the capsule whole and do not crush, chew, break, or open it.

Only tasimelteon capsules should be used in people 16 years and older. Tasimelteon oral suspension is for use only in children who are 3 to 15 years old.

Shake the oral suspension for at least 30 seconds before you measure a dose. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

Read and carefully follow the Instructions for Use provided with the oral suspension syringe and press-in bottle adapter. Ask your doctor or pharmacist if you do not understand these instructions.

After you take tasimelteon, avoid doing anything other than getting ready for bed.

Tasimelteon doses are based on weight in children. Your child's dose needs may change if the child gains or loses weight.

It may take several weeks or months before your symptoms improve. Keep using the medication as directed and tell your doctor if your symptoms do not improve.

Store capsules at room temperature away from moisture, heat, and light.

Store the liquid medicine in the refrigerator. Throw away any leftover liquid 5 weeks after opening the 48-milliliter bottle, or 8 weeks after opening the 158-milliliter bottle.


Why do we sleep? See Answer
Hetlioz Patient Information including If I Miss a Dose

What happens if I miss a dose (Hetlioz)?

Tasimelteon should be taken only at your normal bedtime. Skip any missed dose. Do not use two doses at one time.

What happens if I overdose (Hetlioz)?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking tasimelteon (Hetlioz)?

Avoid driving or hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.

Drinking alcohol may increase drowsiness caused by tasimelteon.

What other drugs will affect tasimelteon (Hetlioz)?

Using tasimelteon with other drugs that make you drowsy can worsen this effect. Ask your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective.

Other drugs may affect tasimelteon, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Where can I get more information (Hetlioz)?

Your pharmacist can provide more information about tasimelteon.

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Health Solutions From Our Sponsors