Generic name: calcium oxybate, magnesium oxybate, potassium oxybate, and sodium oxybate [ KAL-see-um, mag-NEE-zee-um, poe-TAS-ee-um, and-SOE-dee-um-OX-i-bate ]
Dosage form: oral solution(0.5 g per mL)
Drug class: Miscellaneous anxiolytics, sedatives and hypnotics

Medically reviewed by Melisa Puckey, BPharm. Last updated on Mar 26, 2025.

What is Xywav?

Xywav is a medicine used to treat cataplexy (sudden loss of muscle strength) or to reduce excessive daytime sleepiness (EDS) caused by narcolepsy. Xywav is also used in adults to treat idiopathic hypersomnia (IH), which is an uncommon, chronic sleep disorder that causes daytime sleepiness even after a good night's sleep.

Xywav helps to improve the quality and quantity of deep sleep at night, which reduces excessive daytime sleepiness and the number of sleeping periods during the day and improves cataplexy. 

Xywav is a central nervous system depressant. It is an oral solution containing a combination of calcium oxybate, potassium oxybate, magnesium oxybate, and sodium oxybate. One of the ingredients in Xywav, sodium oxybate, is the sodium salt of gamma-hydroxybutyrate (GHB), a known street drug of abuse.

Who can use Xywav?

Xywav is FDA approved to treat:

• Idiopathic hypersomnia (IH) in adults.
• Cataplexy or excessive daytime sleepiness (EDS) in patients 7 years of age and older with narcolepsy.

Xywav FDA approval was received on July 22, 2020, to treat cataplexy or excessive daytime sleepiness caused by narcolepsy. FDA approval for Xywav for idiopathic hypersomnia (IH) was granted on August 12,2021 based on positive results from clinical trial called Study 2, (NCT03533114).

What are narcolepsy and idiopathic hypersomnia?

Narcolepsy is a sleep disorder that causes excessive daytime sleepiness (EDS), frequent sudden daytime attacks of sleep and cataplexy. Narcolepsy can cause you to fall asleep at any time during the day, but it also can keep you from sleeping well at night. You do not get enough sleep over a 24-hour period. Narcolepsy can cause excessive daytime sleepiness and cataplexy, which is a sudden loss of muscle strength that may cause you to fall to the ground.

Idiopathic hypersomnia is a condition that causes you to be very sleepy during the day, even after a good night’s sleep. It can also cause difficulty waking up after you've been asleep.

Is Xywav a controlled substance?

Yes, Xywav is a Schedule III controlled substance (CIII), which means it has a potential for abuse less than substances in Schedules 1 and 2, and it has an accepted medical use in treatment in the United States. Abuse of this medicine may lead to moderate or low physical dependence or high psychological dependence.

Xywav Prescription form and REMS program

Xywav is only available through the Xywav REMS (Evaluation and Mitigation Strategy) program due to the potential for abuse and risk of the serious side effects of significant CNS and respiratory depression. The REMS program goal is to reduce the risks of serious adverse outcomes resulting from inappropriate prescribing, misuse, abuse, and diversion. 

The patient receiving the prescription must read all relevant material, receive counseling from the prescriber, fill out the Xywav Patient Enrollment Form, and fill out the Patient Counseling Checklist with the pharmacist. You must be registered in the program and understand the risks and benefits of this medicine. The Xywav REMS programs require the prescriber and dispensing pharmacists to be certified and follow all guidelines. 

Xywav Prescription Form

The Xywav Prescription form must be filled out at the start of treatment and if there is a break in treatment for 6 months or longer.  The Xywav prescription form does not need to be completed for refills and renewals of prescriptions.

Once the Xywav Prescription form, and the patient and prescriber enrollment forms are all completed they are sent to the Xywav REM.

The Xywav prescription form is available online to healthcare providers Jazz Pharmaceutical REMS page.

Xywav Side Effects

Common Xywav side effects

Common Xywav side effects may include:

• sleepwalking, talking, or eating in your sleep;
• new sleep problems, strange dreams, night terrors;
• drowsiness, dizziness, tiredness, headache;
• tremors, anxiety;
• dry mouth, nausea, vomiting, diarrhea;
• decreased appetite 
• sweating or
• bedwetting (in children).

Serious Xywav side effects 

Get emergency medical help if you have signs of an allergic reaction with symptoms of  hives, difficulty breathing, swelling of your face, lips, tongue, or throat.

Xywav can cause other serious side effects, call your doctor at once if you have:

• weak or shallow breathing, breathing that stops for short periods of time;
• severe drowsiness, feeling light-headed;
• sleepwalking (may result in an injury), waking and confused behavior at night;
• a seizure;
• depression, anxiety, unusual or unpleasant thoughts;
• feelings of low self-worth, loss of interest in things you once enjoyed;
• confusion, paranoia, hallucinations (seeing or hearing things);
• increased tiredness, trouble concentrating, or
• suicidal thoughts or actions.

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.

Related/similar drugs

Warnings

Xywav can cause severe drowsiness and can slow or stop your breathing, even at regular doses or if you are also taking stimulant medicines. You should not do anything that requires you to be fully awake or is dangerous, including driving a car, using heavy machinery, or flying an airplane for at least 6 hours after taking this medicine. Those activities should not be done until you know how this medicine affects you or your child.

Fatal side effects can occur if you take Xywav with alcohol, other sleep medicines, or other drugs that cause drowsiness or slow your breathing.

Misuse of Xywav can cause breathing problems, seizures, loss of consciousness, or death. Keep the medication in a place where others cannot get to it.

Xywav may be habit-forming. Misuse can cause addiction, overdose, or death. Keep the medication in a place where others cannot get to it. Selling or giving away this medicine may harm others and is against the law. Tell your doctor if you have ever abused or been dependent on alcohol, prescription medicines, or street drugs.

Depression and suicidality. You should be monitored for emerging or increased depression and suicidality.

This medicine may cause confusion or anxiety.

May cause episodes of sleepwalking.

Before taking this medicine

Do not drink alcohol or take other sleep medicines together with Xywav. Dangerous side effects or death could occur.

Do not give Xywav to anyone with a rare metabolic disorder called succinic semialdehyde dehydrogenase deficiency (which can cause mental or physical impairment).

To make sure you can safely take Xywav, tell your doctor if you have ever had:

• breathing problems;
• snoring or sleep apnea (breathing stops during sleep);
• depression or suicidal thoughts;
• psychosis or unusual behaviors (anxiety, agitation, paranoia, aggression, hallucinations);
• liver disease; or
• a drug addiction.

Not approved for use by anyone younger than 7 years old for narcolepsy. 

Not approved for use by anyone younger than 18 years old for idiopathic hypersomnia.

Pregnancy

Tell your doctor if you are pregnant or plan to become pregnant. It is not known if Xywav can harm your unborn baby.

Breastfeeding 

Tell your healthcare professional if are breastfeeding or plan to breastfeed. Xywav passes into breast milk. You and your doctor should decide if you or your child will take Xywav or breastfeed.

How should I take Xywav?

Take Xywav exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. This medicine can cause severe drowsiness and can slow or stop your breathing, even at regular doses or if you are also taking stimulant medicine.

Xywav may be habit-forming. Misuse can cause addiction, overdose, or death. Keep the medication in a place where others cannot get to it. Selling or giving away this medicine is against the law. Do not allow anyone else to use this medicine.

Xywav instructions

Wait at least 2 hours after eating before taking or giving Xywav.

Xywav is taken as 1 nightly dose, or as 2 doses (once at bedtime and again 2.5 to 4 hours later). 

Xywav must be mixed with 2 ounces (1/4 cup) of water in the child-resistant dosing cups provided with the medication.

If you take 2 nightly doses, prepare both doses while you are getting ready for bed. Place the second dose in a secure location next to your bed so you can take it without getting up. You may need to set an alarm to awaken for the second dose.

This medicine works quickly. Most people fall asleep within 5 to 15 minutes.

Take Xywav only while you are sitting in bed, ready for sleep. Some people have fallen asleep while standing or getting up from bed, which has caused injuries serious enough to need treatment in a hospital.

Do not allow a child to use this medicine without adult supervision.

Do not change your dose or stop using this medicine suddenly, or you could have unpleasant withdrawal symptoms. Ask your doctor how to stop using this medicine safely.

Store at room temperature, away from moisture and heat. Keep your medicine in a place where no one can use it improperly.

Throw away any dose not used within 24 hours after mixing.

Do not keep leftover Xywav liquid. Ask your pharmacist where to locate a drug take-back disposal program. If there is no take-back program, pour any unused liquid medicine down a sink drain.

Xywav Dosing information

Usual Adult Dose of Xywav Narcolepsy

Initial dose: 4.5 g orally per day, divided and given as 2 equal doses of up to 2.25 g/dose

Maintenance dose: The dose may be increased by 1.5 g (OR 0.75 g/dose) orally per night in weekly intervals up to 6 to 9 g/day.

Maximum dose: 9 g/day

Comments:

• Both doses should be diluted at the same time at night.
• The first dose should be taken at bedtime and the other dose should be taken between 2.5 to 4 hours after; some may need to set an alarm to awaken to take the second dose.
• Patients should remain in bed after taking each dose.
• If the second dose is missed, patients should skip the dose and should not take this drug until the next night.
• Dosing may be gradually titrated, and doses should be determined by efficacy and tolerability.

Use: Treatment of cataplexy (excessive daytime sleepiness) in patients with narcolepsy

Usual Adult Dose of Xywav Idiopathic Hypersomnia (18 years and older)

Two times a night regimen:

Initial dose: 4.5 g orally per day, divided and given as 2 equal doses

The dose may be increased by 1.5 g (OR 0.75 g/dose) orally per night in weekly intervals

Maintenance dose: 6 to 9 g/day

Maximum dose: 9 g/day

Once a night regimen:

Initial dose: 3 g orally per day, divided and given as 2 equal doses

The dose may be increased by 1.5 g (OR 0.75 g/dose) orally per night in weekly intervals

Maintenance dose: 3 to 6 g/day

Maximum dose: 6 g/day

Comments:

• This drug may be given in divided doses or as a single dose.
• Dosing may be gradually titrated, and doses should be determined by efficacy and tolerability.
• Patients may respond better with the first dose given at bedtime and the second dose given between 2.5 to 4 hours later.

Use: Treatment of idiopathic hypersomnia

Usual Pediatric Dose for Narcolepsy (7 years and older)

Less than 20 kg:

Specific dosing recommendations are not available.

20 to less than 30 kg:

Initial dose: Up to 2 g orally per day, divided and given as 2 equal doses of up to 1 g/dose

Maintenance dose: The dose may be increased by 1 g (OR 0.5 g/dose) orally per night at 1 to 2-week intervals up to 6 g/day.

Maximum dose: 6 g/day

30 to less than 45 kg:

Initial dose: Up to 3 g orally per day, divided and given as 2 equal doses of up to 1.5 g/dose

Maintenance dose: The dose may be increased by 1 g (OR 0.5 g/dose) orally per night at 1 to 2-week intervals up to 7.5 g/day.

Maximum dose: 7.5 g/day

45 kg and greater:

Initial dose: Up to 4.5 g orally per day, divided and given as 2 equal doses of up to 2.25 g/dose

Maintenance dose: The dose may be increased by 1.5 g (OR 0.75 g/dose) orally per night at 1 to 2-week intervals up to 9 g/day.

Maximum dose: 9 g/day

Comments:

• Patients who sleep more than 8 hours/night may be given the first dose at bedtime or after an initial period of sleep.
• Patients weighing less than 20 kg may be given lower initial, maximum, maintenance, and total maximum nightly doses.
• Unequal doses may be required in some patients to attain an optimal response to treatment.
• Both doses should be diluted at the same time at night.
• The first dose should be taken at bedtime, and the other dose should be taken between 2.5 to 4 hours after; some may need to set an alarm to awaken to take the second dose.
• Patients should remain in bed after taking each dose.
• If the second dose is missed, patients should skip the dose and should not take this drug until the next night.
• Dosing may be gradually titrated, and doses should be determined by efficacy and tolerability.

Use: Treatment of cataplexy (excessive daytime sleepiness) in patients with narcolepsy.

What happens if I miss a dose?

Skip the missed dose and use your next dose at the regular time. Do not use two doses at one time.

Take Xywav only during your normal sleeping hours (wait at least 2 hours after eating).

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of Xywav can be fatal.

Overdose symptoms may include sweating, vomiting, severe confusion, loss of balance or coordination, or seizure (convulsions).

What should I avoid while taking this medicine?

Do not drink alcohol. Dangerous side effects or death could occur.

Do not take other sleep medicines together with Xywav.

Xywav will cause drowsiness and can impair your thinking or reactions. You may still feel sleepy the morning after taking this medicine. Wait at least 6 hours or until you are fully awake before you drive, operate machinery, pilot an airplane, or do anything that requires you to be awake and alert

What other drugs will affect this medicine?

Fatal side effects can occur if you take Xywav with other drugs that cause drowsiness or slow your breathing. Ask your doctor before taking cold or allergy medicine, opioid medication, sedatives, muscle relaxers, seizure medicine, or medicine for depression, anxiety, or mental illness.

If you start or stop taking divalproex (Depakote), your doctor may need to adjust your Xywav dose.

Other drugs may interact with calcium, magnesium, potassium, and sodium oxybates, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all other medicines you use.

Xywav Prescribing Information 

Review the Xywav Prescribing Information (PI)  for more detailed information about this medicine. The PI contains more detailed information on Indications and Usage, Dosage and Administration, Clinical Pharmacology, Clinical Studies, Drug Interaction, and more. Discuss any medical questions you have with your doctor or other health care provider. This is not all the information you need to know about this medicine for safe and effective use, and it does not take the place of talking to your doctor about your treatment.

Xywav Prescibing Information is sometimes called Xywav Package or FDA label.

Ingredients

Active ingredients: calcium oxybate, magnesium oxybate, potassium oxybate, and sodium oxybate (gamma-hydroxybutyrate (GHB)).

Inactive ingredients: purified water and sucralose.

Storage

• Keep out of reach of children.
• Xywav should be stored between 20°C to 25°C (68°F to 77°F).
• Dispense in tight containers.
• Solutions prepared following dilution should be consumed within 24 hours.

Company 

Xywav Jazz Pharmaceuticals, Inc. Palo Alto, CA 94304

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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