Key takeaways
- Xywav is a prescription drug used to treat excessive daytime sleepiness and cataplexy in adults and certain children with narcolepsy, as well as idiopathic hypersomnia in adults. It comes as a liquid solution that you swallow.
- The starting dosage for adults with narcolepsy is 4.5 grams (g) divided into two doses, taken at night. For adults with idiopathic hypersomnia, the starting dosage is either 3 g taken at night as a single dose or 4.5 g divided into two doses.
- Xywav must be taken on an empty stomach at least 2 hours after eating. Most people fall asleep within 5 to 15 minutes after taking a dose.
Xywav is used to treat excessive daytime sleepiness and cataplexy in adults and some children with narcolepsy. It’s also prescribed for adults with idiopathic hypersomnia (excessive daytime sleepiness of unknown cause).
The active ingredients in Xywav are calcium, magnesium, potassium, and sodium oxybates. (An active ingredient is what makes a drug work.) Xywav is a central nervous system (CNS) depressant.
This article describes the dosages of Xywav, as well as its strength and how to take it. To learn more about Xywav, see this in-depth article.
The table below highlights the basics of Xywav’s dosage for adults. All doses are listed in grams (g). See “What’s the dosage of Xywav in children?” below for information about recommended dosages for children.
| Condition | Starting dosage | Maintenance dosage | Maximum dosage |
|---|---|---|---|
| narcolepsy | 4.5 g, divided into two doses | 6 to 9 g, divided into two doses | 9 g, divided into two doses |
| idiopathic hypersomnia | • 3 g or less as a single dose, or • 4.5 g or less, divided into two doses | weekly increase of 1.5 g per night until symptoms are improved | • 6 g given as a single dose, or • 9 g, divided into two doses |
Keep reading for more details about Xywav’s dosage.
Xywav forms
Xywav is available as a liquid solution that you swallow.
Xywav strengths
Xywav comes in a strength of 0.5 grams per milliliter (g/mL).
Your doctor will likely start you on a low dosage and adjust it over time to reach the right amount for you. They’ll ultimately prescribe the smallest dosage that provides the desired effect.
The information below describes dosages that are commonly used or recommended. But be sure to take the dosage your doctor prescribes for you. They’ll determine the best dosage to fit your needs.
Dosage for narcolepsy
The usual starting dosage of Xywav for adults with narcolepsy is 4.5 g at night. This dosage is divided into two doses. You’ll take the first dose at bedtime and the second dose 2.5 to 4 hours later. Your doctor may divide your dosage into two equal doses. Or they may divide the dosage unequally and recommend that you take a different amount for the first and second doses.
Each week, your doctor will increase your nightly dosage by 1.5 g until you reach the best dosage for you. At the maintenance dosage, you should experience fewer cataplexy attacks and less sleepiness during the day. The recommended nightly dosage ranges from 6 to 9 g. The maximum dosage is 9 g.
Dosage for idiopathic hypersomnia
For adults with idiopathic hypersomnia, the typical dosage of Xywav depends on whether you’re taking the drug once or twice per night. And if you’re taking Xywav twice per night, your doctor may split your dosage into two equal doses or two different doses.
The following table summarizes the dosage for idiopathic hypersomnia.
| Dose frequency | Starting dosage | Weekly dosage increase | Maximum dosage |
|---|---|---|---|
| once per night | 3 g per night | 1.5 g per night | 6 g per night |
| twice per night | 4.5 g per night | 1.5 g per night | 9 g per night |
Note: The starting and weekly dosage increases listed in the table are the maximum amounts. Your doctor may prescribe a lower dosage for you.
Each week, your doctor will increase your nightly dosage by 1.5 g until you reach the best dosage for you. At the maintenance dosage, you should experience less sleepiness during the day.
Xywav is used to treat symptoms of narcolepsy in children ages 7 years and older. Two doses are taken each night. The values in the table below apply to the dose taken at bedtime and the second dose taken 2.5 to 4 hours later.
The dosage is based on your child’s body weight in kilograms (kg). One kilogram is approximately 2.2 pounds (lb). The table below shows dosage recommendations provided by the manufacturer, but your child’s doctor will determine the best dosage for them.
| Body weight | Starting dose | Weekly dose increase | Maximum dose |
|---|---|---|---|
| 20 to 30 kg | 1 g or less | 0.5 g | 3 g |
| 30 to 45 kg | 1.5 g or less | 0.5 g | 3.75 g |
| 45 kg or more | 2.25 g or less | 0.75 g | 4.5 g |
Note: The starting and weekly dosage increases listed in the table are the maximum amounts. Your doctor may prescribe a lower dosage for you.
The two doses each night may be the same, or your child’s doctor may recommend different doses for each of the two doses.
The dosage will be slowly increased each week until your child has fewer cataplexy episodes and less sleepiness during the day. For more information about Xywav’s dosage for children, talk with your child’s doctor.
Xywav is available as a liquid solution. Before bedtime, you’ll prepare each dose by mixing the Xywav liquid solution with 60 mL (1/4 cup) of water. Put the prepared dose (or doses) next to your bed.
Stop eating at least 2 hours before you plan to go to bed. Xywav should not be taken within 2 hours of eating.
When you’re in bed, drink your dose of Xywav. Most people will fall asleep within 15 minutes, and some people fall asleep within 5 minutes.
If you’re taking a second dose, have an alarm set for the time. It’s usually 2.5 to 4 hours after the first dose. When your alarm goes off, drink the second dose. Stay in bed after the second dose.
For information on the expiration, storage, and disposal of Xywav, talk with your doctor or pharmacist. You can also see the “Xywav expiration, storage, and disposal” section of this article.
Accessible drug containers and labels
Some pharmacies provide medication labels that:
- have large print
- use braille
- feature a code you can scan with a smartphone to change the text to audio
Ask your pharmacist if they offer these accessibility features.
Let your pharmacist know if you have trouble opening medication bottles. They may have tips to help, or they may be able to supply easy-open containers.
Is Xywav used long term?
Yes, Xywav is usually a long-term treatment. If you and your doctor determine that it’s safe and effective for your condition, you’ll likely take it long term.
Do not take more Xywav than your doctor prescribes, as this can lead to harmful effects.
Symptoms of overdose
Symptoms caused by an overdose of Xywav may include:
- decreased consciousness and coma
- loss of control of urine and stool
- confusion and agitation
- problems with coordination
- blurry vision
- seizures
- Cheyne Stokes breathing (atypical breathing pattern)
- slow heart rate
- drop in body temperature
What to do in case you take too much Xywav
If you think you’ve taken too much Xywav, you should immediately call 911 (or your local emergency number). If someone is available at home, you should alert them, too.
Disclaimer: Healthline 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.