Xywav (Calcium, Magnesium, Potassium, and Sodium Oxybates) - Oral


Xywav has a boxed warning about the potential of central nervous system (CNS) depression and abuse and misuse. Xywav is a CNS depressant. Respiratory depression (breathing problems) can occur in people using Xywav at recommended doses. The abuse or misuse of illicit oxybate, also known as gamma-hydroxybutyrate, is associated with CNS adverse reactions. This includes seizure, respiratory depression, decrease in the level of consciousness, coma, and death. Because of the risks of CNS depression and abuse and misuse, Xywav is available only through a restricted program under a Risk Evaluation and Mitigation Strategy (REMS) program called the XYWAV and XYREM REMS.

What Is Xywav?

Xywav is a central nervous system (CNS) depressant that treats sleeping disorders in people 7 years of age and older.

Xywav is a combination of different oxybate molecules: calcium, magnesium, potassium, and sodium oxybates. The molecule oxybate is also known as gamma-hydroxybutyrate, or GHB, and is the active ingredient in Xywav. It is not known exactly how GHB affects sleep. However, the most common theory is that it acts on GABA receptors in the brain, which help regulate sleep.

GHB by itself is a Schedule I drug and has no legal use. Xywav is a Schedule III controlled substance, which means it is tracked and regulated more carefully than a normal prescription drug. A Schedule III class for a drug also means that there is moderate to low potential for physical or psychological dependence. Xywav has its own monitoring program called a REMS program. You will need to get it from a pharmacy that is certified to dispense it, rather than a local pharmacy.

Drug Facts

Generic Name: Calcium, magnesium, potassium, and sodium Oxybates

Brand Name: Xywav 

Drug Availability: Prescription

Therapeutic Classification: CNS Depressant

Available Generically: No

Controlled Substance: Schedule III

Administration Route: Oral

Active Ingredient: Oxybate (GHB or gamma-hydroxybutyrate)

Dosage Form: Solution

What Is Xywav Used For?

Xywav is approved for two indications: daytime sleepiness and cataplexy in narcolepsy, and idiopathic hypersomnia.

Individuals with narcolepsy may have any number of four symptoms: excessive daytime sleepiness (EDS), cataplexy, hallucinations, and sleep paralysis. Xywav is approved to treat two of these: EDS and cataplexy. Cataplexy is the sudden onset of weak or paralyzed muscles. A person may lose control of their muscles and collapse in any given situation.

Idiopathic hypersomnia (IH) causes excessive sleepiness during the day even after a good night's sleep. Like narcolepsy, it can be dangerous because the sleepiness can strike at any time, like while driving or working. However, IH does not include cataplexy.

Xywav ( Calcium, Magnesium, Potassium, and Sodium Oxybates) Drug Information - Illustration by Zoe Hansen

Verywell / Zoe Hansen

How to Take Xywav

Xywav is taken by mouth two times per night, once at bedtime and again two and a half to four hours later. The dose will likely be started on the lower end and may be increased by your healthcare provider based on how much it’s helping you and how well you’re tolerating it.

Prepare both doses of Xywav prior to bedtime. Each dose is prepared by adding about ¼ cup (60 milliliters) of water to Xywav in the empty containers provided. Once prepared, doses need to be consumed within 24 hours. Take Xywav while you’re in bed, and lie down right after you take it. It may cause you to fall asleep abruptly without first feeling drowsy.

You may need to set an alarm to wake yourself up for your second dose each night. You can keep Xywav by your bed so you don’t have to get up to take the dose. If the second dose is missed, skip it and don’t take Xywav again until the next night. Never take two doses at one time.


Store Xywav at room temperature (68 degrees to 77 degrees F). Once you prepare your Xywav dose, it needs to be taken within 24 hours, so only prepare one night’s worth (two doses) at a time. If you need to waste a dose, it is safe to dispose of Xywav down the drain.

When traveling, keep Xywav packed in your carry-on luggage with the lid on tight. Make sure to bring your prescription information and notify TSA personnel when you’re going through security that you have the drug with you.

How Long Does Xywav Take to Work?

After taking Xywav, you will typically fall asleep within five to 15 minutes, though this may vary from night to night. Take Xywav while you’re in bed lying down, as it may cause you to fall asleep abruptly without feeling drowsy first.

What Are the Side Effects of Xywav?

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at fda.gov/medwatch or 1-800-FDA-1088.

Common Side Effects

The following are some of the more common side effects of Xywav. If you notice these side effects and think they are severe or do not go away you should notify your healthcare provider:

  • Headache
  • Nausea
  • Dizziness
  • Decreased appetite
  • Abnormal dreams
  • Night sweats

Severe Side Effects

Notify your healthcare provider right away if you notice these side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • CNS depression. Significant respiratory depression (breathing problems) and a lowered level of consciousness have occurred in some people taking Xywav, as it is a CNS depressant. Wait until you know how Xywav affects you before you drive or operate other machinery.
  • Abuse and misuse. The active ingredient in Xywav, oxybate or GHB, does have abuse and misuse potential due to its rapid onset of action and amnestic features, or its ability to cause some short-term memory loss. GHB is a schedule I (illegal) drug that is sometimes used on victims of assault–a “date-rape drug”. This is why it is important to avoid use with alcohol and to be cautious in individuals who may have a history of drug abuse or misuse.
  • Neuropsychiatric reactions. Some adults have experienced hallucinations, paranoia, aggression, or agitation while on Xywav. Make sure to let your healthcare provider know as soon as possible if you think Xywav may be affecting you in these ways.

Long-Term Side Effects

As long as you continue to take Xywav exactly as prescribed, no side effects are known to emerge after long-term use compared to the shorter-term effects listed above.

Report Side Effects

Xywav may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Xywav Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (solution):
    • For cataplexy or excessive daytime sleepiness:
      • Adults—At first, 2.25 grams (g) taken at bedtime (first dose), then 2.25 g taken 2.5 to 4 hours later (second dose). Your doctor may adjust your dose as needed and tolerated. However, the dose is usually not more than 9 g per night.
      • Children 7 years of age and older—Dose is based on body weight and must be determined by your doctor:
        • Weighing 45 kilograms (kg) or more—At first, 2.25 g or less given at bedtime and repeated one time during the night. The first dose should be taken at bedtime and the second dose taken 2.5 to 4 hours later. Your doctor may adjust your dose as needed and tolerated. However, the dose is usually not more than 4.5 g per night.
        • Weighing 30 kg to less than 45 kg—At first, 1.5 g or less given at bedtime and repeated one time during the night. The first dose should be taken at bedtime and the second dose taken 2.5 to 4 hours later. Your doctor may adjust your dose as needed. However, the dose is usually not more than 3.75 g per night.
        • Weighing 20 to less than 30 kg—At first, 1.0 g or less given at bedtime and repeated one time during the night. The first dose should be taken at bedtime and the second dose taken 2.5 to 4 hours later. Your doctor may adjust your dose as needed. However, the dose is usually not more than 3 g per night.
      • Children younger than 7 years of age or weighing less than 20 kg—Use and dose must be determined by your doctor.
    • For idiopathic hypersomnia:
      • Once a night dosing:
        • Adults—At first, 3 grams (g) or less taken at bedtime. Your doctor may adjust your dose as needed and tolerated. However, the dose is usually not more than 6 g per night.
        • Children—Use and dose must be determined by your doctor.
      • Two times a night dosing:
        • Adults—At first, 4.5 grams (g) or less taken at bedtime, divided into two doses (eg, 2.25 g each). Your doctor may adjust your dose as needed and tolerated. However, the dose is usually not more 9 g per night.
        • Children—Use and dose must be determined by your doctor.


Treatment with Xywav may need to be modified for certain populations, depending on circumstances such as pregnancy, age, and other health conditions.


There is not sufficient data regarding the safety of taking Xywav while pregnant. The benefit of treating narcolepsy or idiopathic hypersomnia should be weighed against any risk that Xywav may pose to a pregnancy.


GHB, the active ingredient in Xywav, is excreted in human milk. How much of the drug that may get into breast milk or the effect it may have on a baby is not well understood. The need for Xywav should be considered and weighed against any potential risk to the baby.


Xywav has been established as safe and effective to treat excessive daytime sleepiness and cataplexy in children with narcolepsy at least 7 years old and older. This has not been established in children younger than 7.

Older Adults

Clinical trials of Xywav did not have sufficient numbers of individuals over age 65 to say with much confidence if they respond differently to Xywav than younger adults do. Older adults had a higher frequency of headaches, and slightly more older adults people discontinued the drug than younger people. Therefore, older adults should be started at a lower dose, considering other possible factors like liver or kidney function.

Liver Disease

If you have liver disease, you will likely start at a lower dose of Xywav, as you may be exposed to more drug if you have a lower liver function.

Missed Dose

Since your second dose of Xywav will be in the middle of the night, you may miss a dose sometimes. Set an alarm to wake yourself up for this second dose, but if you miss it, just skip that dose and take Xywav as usual the next night. Never take two doses at one time.

Overdose: What Happens If I Take Too Much Xywav?

Take Xywav exactly as prescribed by your healthcare provider. Information about symptoms associated with Xywav overdose mostly come from reports of illegal use of GHB, which means alcohol is often a factor as well. Symptoms may include varying degrees of low consciousness, and may quickly change to an agitated or combative state. Vomiting, blurred vision, seizures, and trouble breathing are also potential signs and symptoms.

What Happens If I Overdose on Xywav?

If you think you or someone else may have overdosed on Xywav, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Xywav, call 911 immediately.


Drug Content Provided by IBM Micromedex®

It is very important that your doctor check your or your child's progress at regular visits to make sure the medicine is working properly and to check for any unwanted effects.

Do not use this medicine if you are also taking another sedative or hypnotic medicine (eg, Ambien®, Phenergan®, Seconal®). Also, do not drink alcohol while you are using this medicine. Doing so may increase the risk for serious unwanted effects.

It is against the law and dangerous for anyone else to use your medicine. Keep your unused medicine in a safe and secure place. People who are addicted to drugs might want to steal this medicine.

Check with your doctor before using this medicine with alcohol or other medicines that affect the central nervous system (CNS). The use of alcohol or other medicines that affect the CNS with Xywav® may worsen the side effects of this medicine, such as dizziness, poor concentration, drowsiness, unusual dreams, and trouble with sleeping. Some examples of medicines that affect the CNS are antihistamines or medicine for allergies or colds, sedatives, tranquilizers, or sleeping medicines, medicine for depression, medicine for anxiety, prescription pain medicine or narcotics, medicine for attention deficit and hyperactivity disorder, medicine for seizures or barbiturates, muscle relaxants, or anesthetics, including some dental anesthetics.

This medicine may make you dizzy, drowsy, or less alert than you are normally. Do not drive or do anything else that could be dangerous for at least 6 hours after taking this medicine.

Do not use more of this medicine or take it more often than your doctor tells you to. This can be life-threatening. Symptoms of an overdose include: extreme dizziness or weakness, slow heartbeat or breathing, seizures, trouble breathing, or cold, clammy skin. Call your doctor right away if you notice these symptoms.

This medicine may cause some people to be agitated, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. Make sure the doctor knows if you have trouble sleeping, get upset easily, have a big increase in energy, or start to act reckless. Also tell the doctor if you have sudden or strong feelings, such as feeling nervous, angry, restless, violent, or scared. If you or your caregiver notice any of these side effects, tell your doctor right away.

This medicine may cause unusual behavior while you are sleeping. Other people living in your house should monitor you for the possibility of sleep-related problems, including sleepwalking, sleep talking, sleep eating, or bedwetting. Tell your doctor if any of these occur.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or non-prescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn't Take Xywav?

You should not take Xywav if you:

  • Also take sedative hypnotics
  • Drink alcohol
  • Have a condition called succinic semialdehyde dehydrogenase deficiency, a rare metabolism disorder

What Other Medications Interact With Xywav?

There are a few important interactions between Xywav and other drugs.

  • Alcohol should be completely avoided while on Xywav. Like Xywav, alcohol is a CNS depressant and can increase the risk for respiratory depression (breathing problems), low blood pressure, and extreme sedation (sleepiness) or death.
  • Other CNS depressants like benzodiazepines, narcotic painkillers, sedating antipsychotics or antidepressants, muscle relaxers, and sedatives like sleeping pills can all add to the effects that Xywav produces and increase the risk of respiratory depression, low blood pressure, and extreme sedation or death.
  • Depakote (divalproex) is an anti-seizure medication that can also cause CNS depression. When starting divalproex in people taking Xywav, the dose of Xywav should be lowered. If you are already on divalproex, a lower starting dose of Xywav is recommended.

What Medications Are Similar?

Other medications used to treat narcolepsy include:

  • Xyrem (sodium oxybate) is the only other medication with oxybate as the active ingredient. It contains only sodium oxybate, not a mix of other oxybates like Xywav does. Therefore it contains a higher amount of sodium per dose.
  • Wakix (pitolisant) is a histamine antagonist designed to improve individuals’ time awake. It is approved for excessive daytime sleepiness in narcolepsy.
  • Sunosi (solriamfetol) is also approved for excessive daytime sleepiness in narcolepsy. It aims to improve wakefulness by regulating certain chemicals in the brain including dopamine and norepinephrine.

This list is NOT a list of drugs recommended to take with Xywav. In fact, you should not take these drugs together. Ask your pharmacist or a healthcare provider if you have questions.

Frequently Asked Questions

  • How Does Xywav Work?

    The active ingredient in Xywav is called oxybate, which is a major CNS depressant. Taking this medicine before bed and halfway through the night promotes getting good sleep and staying asleep, which can improve narcolepsy symptoms during the day.

  • How long does it take for Xywav to work?

    Most people fall asleep within five to 15 minutes of taking Xywav, sometimes abruptly without feeling drowsy first. For this reason, take Xywav while you’re already lying down in bed, and have your second dose ready at your bedside.

  • What drugs should not be taken with Xywav?

    It’s important to avoid other CNS depressants while you’re taking Xywav, including benzodiazepines, muscle relaxants, sleeping pills, and opioid painkillers.

How Can I Stay Healthy While Taking Xywav?

Narcolepsy is thought to be caused in part by a low amount of a substance in your brain called hypocretin. Hypocretin promotes wakefulness and maintains your normal muscle functioning. Unfortunately, there is no cure for narcolepsy, but some behavior changes and medications can help.

The loss of control you may feel when you have narcolepsy, especially with the loss of muscle control that comes with cataplexy, can feel dangerous and downright scary. It can be frustrating to try to maintain a career and relationships while struggling with narcolepsy. Educate your friends and family about the condition to give them the opportunity to best support you in dealing with it.

Avoiding substances that can either increase or decrease your energy level (e.g., alcohol, allergy medicines, caffeine) can help improve narcolepsy symptoms. So can medications like Xywav that are focused on improving your time asleep and helping you stay asleep at night. Further treatments are being developed and studied in clinical trials to continue identifying new ways to help people with narcolepsy and idiopathic hypersomnia.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Olsen RW, DeLorey TM. GABA Receptor Physiology and Pharmacology. In: Siegel GJ, Agranoff BW, Albers RW, et al, eds. Basic Neurochemistry: Molecular, Cellular and Medical Aspects. 6th edition. Philadelphia: Lippincott-Raven; 1999.

  2. Food and Drug Administration. Xywav package insert.

  3. Thorpy MJ. Recently approved and upcoming treatments for narcolepsy. CNS Drugs. 2020;34(1):9-27. doi:10.1007/s40263-019-00689-1

By Sara Hoffman, PharmD
Sara is a clinical pharmacist that believes everyone should understand their medications, and aims to achieve this through her writing.