Xyrem is a prescription medication used to treat two core symptoms of narcolepsy: cataplexy (sudden episodes of muscle weakness) and excessive daytime sleepiness. It is FDA-approved for patients 7 years of age and older. The active ingredient is sodium oxybate, a liquid taken by mouth at night that works by deepening sleep quality so patients feel more rested and alert during the day.
What Xyrem Treats
Narcolepsy is a chronic neurological condition where the brain struggles to regulate sleep-wake cycles normally. People with narcolepsy often experience overwhelming daytime drowsiness no matter how much they sleep, and many also have cataplexy, where strong emotions like laughter or surprise trigger a sudden loss of muscle tone. Cataplexy can range from a brief drooping of the eyelids to a full collapse.
Xyrem targets both of these problems. In clinical trials, patients who were taken off Xyrem and switched to a placebo experienced a dramatic return of cataplexy, averaging roughly 13 additional attacks per week, while those who stayed on the medication saw essentially no change. That difference was statistically significant, confirming that the drug actively suppresses cataplexy rather than simply masking symptoms temporarily.
How It Works
Sodium oxybate is the pharmaceutical form of gamma-hydroxybutyrate (GHB), a substance your brain naturally produces in small amounts from GABA, one of its primary calming chemicals. When taken as a medication, it activates receptors in the brain that promote deep, restorative slow-wave sleep. People with narcolepsy typically have fragmented, poor-quality nighttime sleep even though they’re excessively sleepy during the day. By increasing the amount of deep sleep at night, Xyrem helps correct that imbalance, leaving patients more alert and functional during waking hours and reducing the frequency of cataplexy episodes.
How You Take It
Xyrem has an unusual dosing schedule compared to most medications. It is a liquid that you take in two separate doses each night. The first dose is taken at bedtime while you’re already in bed, and the second dose is taken 2.5 to 4 hours later (most people set an alarm). You need to eat your last meal at least two hours before the first dose, because food significantly affects how the drug is absorbed. Because sodium oxybate is a powerful sedative, you must be lying in bed and ready to sleep before each dose. The medication takes effect quickly, typically within 15 to 30 minutes.
Common Side Effects
The most frequently reported side effects in adults are nausea, dizziness, vomiting, daytime drowsiness, bedwetting, and tremor. Many of these are dose-dependent, meaning they become more common at higher doses. At the highest studied dose (9 grams per night), nausea affected about 20% of patients compared to 3% on placebo, and dizziness occurred in 15% versus 4% on placebo. Bedwetting affected about 7% of adults at higher doses.
Some people also report feeling disoriented, experiencing sleep paralysis, or sleepwalking. These side effects occurred in roughly 3% of patients at higher doses in clinical trials.
Children 7 and older tend to experience a somewhat different side effect profile. Bedwetting is more common in younger patients, affecting about 18%. Nausea and vomiting each occur in about 16 to 17% of pediatric patients, and decreased appetite and weight loss are more notable in this age group, affecting 8% and 12% respectively.
Important Safety Concerns
Because sodium oxybate is chemically related to GHB, it carries a significant risk of misuse and is classified as a controlled substance. It is a potent central nervous system depressant, meaning it slows brain activity substantially. Combining it with alcohol, sleep aids, opioids, or other sedating substances can dangerously suppress breathing and consciousness. This risk is serious enough that Xyrem carries the FDA’s strongest safety warning on its label.
The medication can also worsen sleep-related breathing problems. Patients with conditions like sleep apnea need careful evaluation before starting treatment, as the drug’s sedative properties can make breathing interruptions during sleep more severe.
How Patients Access Xyrem
You cannot pick up Xyrem at a regular pharmacy. Because of its abuse potential, it is distributed through a restricted program called a REMS (Risk Evaluation and Mitigation Strategy). Both your prescriber and you must enroll in the program before treatment can begin. Your doctor submits enrollment forms after reviewing your medical history and screening for substance abuse, sleep-disordered breathing, and any other sedating medications you take. You then receive the medication through a centralized specialty pharmacy that ships it directly to you. Before starting and at certain points during treatment, you’ll complete a counseling checklist with a pharmacist covering safe storage, proper dosing, and what to avoid while on the drug.
Xyrem vs. Xywav
Xywav is a newer alternative that works the same way but contains dramatically less sodium. Xyrem’s maximum nightly dose packs 1,640 mg of sodium, which is a substantial portion of the recommended daily limit of 2,300 mg. Xywav contains just 131 mg of sodium at the same dose, a 92% reduction. For patients managing high blood pressure, heart failure, or kidney problems, that difference matters. Both medications treat the same conditions and are distributed through the same REMS program, so the choice between them often comes down to sodium sensitivity and insurance coverage.