Sodium Oxybate / Oxybate Salts (Xyrem, Xywav)

What it treats

Sodium oxybate (Xyrem) and the mixed oxybate salts (Xywav) are approved by the U.S. Food and Drug Administration for:

• Cataplexy in narcolepsy (adults and pediatric patients 7 years and older).
• Excessive daytime sleepiness in narcolepsy.
• Idiopathic hypersomnia (Xywav, adults).

These are among the most effective medications available for cataplexy, a sudden loss of muscle tone triggered by strong emotion.

How it works

Oxybate is a GABA-B receptor agonist and also acts at GHB-specific receptors. Given at bedtime (and again in the middle of the night), it consolidates sleep, promotes deep slow-wave sleep, and, through mechanisms not fully mapped, reduces daytime sleepiness and cataplexy the next day.

Xywav is chemically the same active molecule as Xyrem but with 92 percent less sodium. That matters for patients with high blood pressure, heart failure, or kidney disease, in whom sodium load from Xyrem can meaningfully affect cardiovascular health.

Receptor mechanism (detail)

Oxybate is a GABA-B receptor agonist with additional activity at GHB-specific receptors. It's the sodium salt of gamma-hydroxybutyrate, the endogenous metabolite of GABA. Given at pharmacologic doses at bedtime, oxybate consolidates and deepens slow-wave sleep. The therapeutic effect on daytime cataplexy and sleepiness is thought to come from restorative slow-wave sleep, though the full mechanism isn't settled.

Potency and typical dosing pattern

Ranges are typical framework only, not a prescription for any individual.

Xyrem/Xywav is dosed twice per night: half the total dose at bedtime, half the total dose 2.5 to 4 hours later. Starting: 4.5 g per night total, split. Titrate weekly by 1.5 g per night to a usual range of 6 to 9 g per night total.

Patients set an alarm to take the second dose in the middle of the night.

Safety monitoring

• CNS depression and respiratory depression. Boxed warning. Do not combine with alcohol, sedatives, opioids, or other CNS depressants.
• Abuse and misuse potential. Boxed warning. Oxybate is the same molecule as illicit GHB. Dispensing is controlled through a REMS program.
• REMS program. Only certified pharmacies dispense; only certified prescribers can prescribe; patients must be enrolled.
• Sodium load with Xyrem. Xywav is preferred in patients with hypertension, heart failure, or kidney disease.
• Depression and suicidality. Watch for new or worsening mood changes.
• Confusion and complex sleep behaviors. Sleepwalking, sleep-eating, enuresis (bedwetting), have been reported.
• Enuresis is not rare and often improves with dose adjustment.

What to expect

Common side effects

• Nausea, especially at initiation.
• Dizziness.
• Headache.
• Sleepwalking or sleep-related confusion.
• Enuresis (bedwetting).
• Reduced appetite.
• Diarrhea.
• Weight loss.

If a side effect is bothersome or persistent, that's a conversation for the prescriber. Enuresis in particular is often manageable with dose adjustment.

Serious side effects and warnings

Boxed warning: CNS depression. Oxybate is a CNS depressant. Combining with alcohol, sedative hypnotics, opioids, or other CNS depressants can cause profound sedation, respiratory depression, coma, and death.

Boxed warning: abuse and misuse. Oxybate is the same molecule as illicit gamma-hydroxybutyrate (GHB), which has a history of abuse and use in drug-facilitated assault. Dispensing is controlled through a REMS program.

• Respiratory depression. Especially in sleep apnea or when combined with other depressants.
• Complex sleep behaviors. Sleepwalking, sleep-driving, sleep-eating, sometimes with amnesia for the events.
• Depression and suicidality. New or worsening mood changes need prescriber contact.
• Confusion, anxiety, psychosis-like symptoms in some patients.
• Enuresis (bedwetting) can occur.
• Alcohol interaction. Do not drink while on oxybate. The combination can be fatal.

Sexual side effects

Oxybate doesn't typically cause chronic sexual side effects the way some daily medications can. Any change is worth mentioning to the prescriber.

Weight, appetite, and sleep

Reduced appetite and modest weight loss are common. Sleep architecture changes are the intended effect: deeper slow-wave sleep, more consolidated sleep, less REM fragmentation.

Starting and dosing basics

This section is general background, not a dosing instruction for any individual. The right dose is a decision for a prescriber.

Xyrem and Xywav come as oral solutions dispensed in specific bottles with dosing cups. Doses are mixed with water (about 2 ounces per dose) and taken twice per night: at bedtime, and again 2.5 to 4 hours later. Both doses are taken while in bed. Food significantly slows absorption, so the medication is taken at least 2 hours after eating.

Missed doses and interactions

If the first (bedtime) dose is missed, the medication is generally not started that night. If the middle-of-the-night dose is missed and the person wakes up too late for a full 2.5 hours before morning, the second dose is skipped.

The critical interactions are alcohol and other CNS depressants. These combinations can be fatal. Sodium oxybate must not be used with these. Other interactions include divalproex, which raises oxybate levels (dose reduction needed).

Give every prescriber and pharmacist the full medication list.

Stopping and tapering

Oxybate doesn't typically require a formal taper. Sleepiness and cataplexy will return over days if the medication is stopped. If someone has been on oxybate a long time, some clinicians choose a gradual reduction. That's a prescriber's decision.

Pregnancy and breastfeeding

Data on oxybate use in pregnancy are limited. Individual circumstances matter, and the decision belongs with a clinician. Anyone pregnant, planning a pregnancy, or breastfeeding should discuss it with their prescriber and the sleep specialist involved.

Cost and generic availability

Sodium oxybate has authorized generics available in some formulations. Xywav (the low-sodium version) remains branded. Both are expensive. Insurance coverage requires prior authorization and REMS enrollment. Manufacturer copay assistance may apply for eligible patients.

Common questions

Is this the same drug as GHB? Chemically, yes. The active molecule in Xyrem and Xywav is gamma-hydroxybutyrate. In prescription form, given at controlled doses under a REMS program, it's a highly effective treatment for cataplexy and narcoleptic sleepiness. The illicit form's danger comes from dose, purity, and setting.

Why is the dosing split into two nighttime doses? Because the medication's half-life is short (2 to 3 hours) and the therapeutic benefit depends on consolidated slow-wave sleep across the whole night. One dose alone would wear off too fast.

Why not just drink alcohol to help me sleep like some people do with GHB? Do not do this. Alcohol plus oxybate is potentially fatal. That is the single most important safety point on this page.

What's Xywav for? Xywav is the lower-sodium version of oxybate. It's designed for patients where sodium load matters (hypertension, heart failure, kidney disease). Otherwise, it's chemically the same active molecule as Xyrem.

What if I have bedwetting or sleepwalking on it? Enuresis and sleepwalking are known effects that the prescriber can help address, often with dose adjustments or timing changes. Don't just stop the medication without contacting them.

Questions to ask your prescriber

• Is Xyrem or Xywav the right choice for me given my other conditions?
• How do we handle the REMS enrollment and dispensing logistics?
• What side effects should I expect, and which ones should I call about?
• What should we do if I take alcohol accidentally?
• How do we handle the middle-of-the-night dose if my sleep pattern changes?

Sources

This guide draws on current prescribing information and public health references and current as of June 8, 2026. It is reviewed for clinical accuracy and updated as guidance changes.

• U.S. Food and Drug Administration. Sodium oxybate (Xyrem) and calcium/magnesium/potassium/sodium oxybates (Xywav) prescribing information.
• MedlinePlus, U.S. National Library of Medicine. Sodium oxybate.
• American Academy of Sleep Medicine. Clinical Practice Guideline for the Treatment of Central Disorders of Hypersomnolence.
• Xyrem/Xywav REMS Program materials.
• National Institute of Neurological Disorders and Stroke. Narcolepsy information page.