Xywav (calcium, magnesium, potassium, and sodium oxybates) is a brand-name oral solution prescribed for certain sleep-wake disorders in adults and some children. It’s typically taken once or twice per night.

Xywav is approved by the Food and Drug Administration (FDA) to treat:

Xywav belongs to a drug class called central nervous system (CNS) depressants. Drugs in this class are also known as sedatives. Xywav is not available in a generic version.

Keep reading for specific information about the dosage of Xywav, including its strength and how to take the medication. For a comprehensive look at Xywav, see this article.

Note: This article describes typical dosages of Xywav provided by the drug’s manufacturer. When taking Xywav, always follow the dosage prescribed by your doctor.

Below is information about Xywav’s form, strength, and dosages.

Xywav form

Xywav comes as an oral solution that you dilute with water before taking. (See “How to take Xywav” below for details.)

Xywav strength

Xywav comes in one strength of 0.5 grams (g) of the drug per 1 milliliter (mL) of solution. Xywav is available in 180-mL bottles.

Typical dosages

Typically, your doctor will start by prescribing a low dosage. Then they’ll titrate (slowly increase) your dose over time to reach the amount that’s right for you. Your doctor will ultimately prescribe the smallest dosage that provides the desired effect.

The following information describes Xywav dosages that are commonly prescribed or recommended in adults. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs. In some cases, doctors may adjust your dosage from those shown below.

Dosage for idiopathic hypersomnia (IH)

For IH, doctors may prescribe either a once-nightly or twice-nightly dosing schedule.

With once-nightly dosing, the recommended starting dose is 3 g or less once per night, taken at bedtime.

With twice-nightly dosing, the recommended starting dose is 4.5 g or less per night, divided into two doses. Typically, the first dose is at bedtime, and the second dose is 2.5 to 4 hours after the first. Keep in mind your doctor may choose to divide your total nightly dose into unequal doses.

With either schedule, your doctor may increase your nightly dose by up to 1.5 g each week to treat your IH. A single dose should be no more than 6 g. With twice-nightly dosing, the maximum recommended dose is 9 g per night.

The table below shows a typical dosing schedule and divided doses (for twice-nightly dosing):

Total nightly doseBedtime doseSecond dose
4.5 g2.25 g2.25 g
6 g3 g3 g
7.5 g3.75 g3.75 g
9 g4.5 g4.5 g

Your doctor will tailor your dose and titration schedule based on your needs and how Xywav is working for you.

For more information about your specific dosage, talk with your doctor.

Dosage for cataplexy or excessive daytime sleepiness (EDS)

Doctors may prescribe Xywav for cataplexy or EDS in people with narcolepsy.

The recommended starting dose is 4.5 g per night, divided into two doses (twice-nightly dosing). The first dose is at bedtime, and the second dose is 2.5 to 4 hours after the first.

Your doctor may increase your nightly dose by up to 1.5 g each week. Typically, they’ll increase your dose until they reach the recommended dosage range. For narcolepsy, this is 6 to 9 g per night. The maximum recommended dosage is 9 g per night.

For details about Xywav’s recommended dosing schedule for twice-nightly dosing, see the table above in “Dosage for idiopathic hypersomnia (IH).” As with IH, your doctor may divide your total nightly dose into unequal doses.

Talk with your doctor if you have questions about your dosage.

Note: If you’ve been taking Xyrem and your doctor recommends Xywav, you’ll likely take the same dosage. If you have questions about this, talk with your doctor for more information.

Children’s dosage

Xywav is approved to treat cataplexy or EDS in children ages 7 years and older with narcolepsy. The recommended dosage is based on the child’s body weight in kilograms (kg). One kg equals about 2.2 pounds (lb).

As for adults, doctors prescribe a low dosage to start and increase it over time. You’ll divide your child’s prescribed nightly dose into two doses (twice-nightly dosing). Similar to twice-nightly dosing for adults, the divided doses may or may not be equal.

Typically, the first dose is at your child’s bedtime, and the second dose is 2.5 to 4 hours after the first. However, always follow the dosing instructions the doctor prescribes.

For children weighing 20 kg (about 44 lb) or more, the typical dosing schedule by body weight is summarized below:

Body weightStarting first doseStarting second doseMaximum nightly dose increase each weekMaximum total nightly dose
20 to 29 kg (about 44 to 64 lb)1 g or less1 g or less1 g per night, divided into two doses6 g, divided into two doses
30 to 44 kg (about 66 to 97 lb)1.5 g or less1.5 g or less1 g per night, divided into two doses7.5 g, divided into two doses
45 kg (about 99 lb) or more2.25 g or less2.25 g or less1.5 g per night, divided into two doses9 g, divided into two doses

If your child weighs less than 44 lb, their doctor may prescribe a lower starting dosage. They may also adjust it differently to reach the desired effect.

Talk with your child’s doctor if you have questions about their dosage.

How to take Xywav

Xywav comes as a solution that you dilute with water and take by mouth. There are instructions for diluting Xywav in the manufacturer’s medication guide. This guide should also be provided with your prescription.

You should wait 2 hours or more after eating before taking Xywav.

It’s best to set up your dose(s) and alarms for the second dose (if prescribed) before bed. You’ll dilute Xywav then.

Xywav causes sleep so quickly that falls and harm can occur. For this reason, be sure to take your doses in bed. Lying down right after a dose helps prevent injuries.

For questions about how to take Xywav, talk with your doctor or pharmacist.

Long-term treatment

Xywav is meant to be a long-term treatment. If you and your doctor determine that Xywav is safe and effective for you, you’ll likely take it long term.

Before you start taking Xywav, your doctor will likely discuss a treatment plan with you. Talk with them if you have questions about how long you can expect to take Xywav.


Some pharmacies offer labels with large print, braille, or a code you scan with a smartphone to convert text to speech. If your local pharmacy doesn’t have these options, your doctor or pharmacist might be able to recommend a pharmacy that does.

Below are some frequently asked questions about Xywav and dosage.

Is the dosage of Xywav similar to the dosage of Lumryz?

The dosages are similar in some ways and different in others. Xywav and Lumryz are both taken as oral liquids. The dose amount for each drug is also comparable because they have similar active ingredients. (Lumryz contains sodium oxybate.)

However, Lumryz comes as extended-release (ER) granules that you make into an oral suspension (a type of liquid mixture). With ER medications, the drug releases slowly into your body over time. Because of this, you take Lumryz once per night. Xywav is taken once or twice per night, depending on how your doctor prescribes it. For details, see the “Xywav dosage” section above.

Your doctor will prescribe the drug and the dosage that’s right for you. To learn more about how these drugs compare, talk with your doctor.

Is there a risk of dependence or withdrawal with Xywav?

Xywav may cause dependence. (With dependence, your body gets used to a drug and needs it to function as usual.) This means you may have withdrawal symptoms if you suddenly stop taking Xywav after taking it regularly. Withdrawal symptoms are unwanted effects that occur after you stop taking a drug your body is dependent on.

Symptoms of withdrawal after abruptly stopping Xywav may include:

These symptoms can be unpleasant but are usually not life threatening. For severe cases, treatment in a hospital may be needed.

If a decision is made to stop Xywav, your doctor may choose to slowly lower your dose over time. This can reduce the risk of withdrawal symptoms. You should not stop taking Xywav unless specifically told by your doctor. If you have questions about taking or stopping Xywav, talk with your doctor.

It’s important that you do not take more Xywav than your doctor prescribes. Taking more than the recommended amount may lead to harmful effects or overdose.

Effects of an overdose

In Xywav’s clinical trials, there were no reported overdoses. However, the prescribing information has data from similar drugs to show what a Xywav overdose may look like.

Overdose effects of Xywav may include:

In severe cases, an overdose of Xywav could even lead to coma.

If you take more than the recommended amount of Xywav

Call your doctor right away if you believe you’ve taken too much Xywav. Another option is to call America’s Poison Centers at 800-222-1222 or use its online tool. If you have severe symptoms, immediately call 911 or your local emergency number, or go to the nearest emergency room.

To learn more about the conditions Xywav is approved to treat, see our science of sleep hub.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.