Sodium oxybate, sold under the brand name Xyrem among others, is a medication used to treat symptoms of narcolepsy: sudden muscle weakness and excessive daytime sleepiness.

[10]: 15, 27–28 The major use of sodium oxybate is in treating two of the symptoms of narcolepsy – cataplexy (sudden muscle weakness) and excessive daytime sleepiness.

[3] Reviews of sodium oxybate concluded that it is well tolerated and associated with "significant reductions in cataplexy and daytime sleepiness",[16] and that its effectiveness "in treating major, clinically relevant narcolepsy symptoms and sleep architecture abnormalities" has been established.

[3] Investigations of its use in dealing with alcohol withdrawal syndrome and in the maintenance of abstinence began in 1989 in Italy, where it was then approved in these indications in 1991.

Results of small studies suggest it may be "better than naltrexone and disulfiram regarding abstinence maintenance and prevention of craving in the medium term, i.e. 3–12 months.

"[18] However, a 2018 review recognised the evidence for its efficacy but noted safety concerns and concluded that "studies are still limited and investigations including a larger number of patients are needed.

"[20] In this context, a study published in 2019 analyzed safety data from 40 clinical trials and from a pharmacovigilance database covering around 260,000 alcohol-dependent patients treated with sodium oxybate in Italy and Austria.

[21] Results showed that sodium oxybate was well-tolerated, risks were controlled, and no safety concerns were reported.

[21] In 2023, a PhD thesis conducted at the University of Amsterdam, presented the results of large clinical trials, including a phase 3 trial, and of meta-analyses that confirmed the efficacy, good tolerance, and safety of sodium oxybate in the maintenance of abstinence, particularly in severe alcohol-dependent patients.

[23] Multiple trials have shown sodium oxybate to be effective in treating important symptoms of fibromyalgia, such as pain and poor sleep structure.

[8][31] Between 1% and 10% of people experience nasal congestion, runny nose, or sore throat, loss of appetite, distorted sense of taste, cataplexy, weakness, nervousness or anxiety, depressed mood, nightmares or abnormal dreams, sleep paralysis, sleepwalking, or other sleep disturbances including insomnia, sleepiness or sedation, falls, vertigo, tremor, balance disorder, cognitive issues including disturbance in attention, confusion or disorientation, numbed sense of touch, tingling, blurred vision, heart palpitations, high blood pressure, shortness of breath, snoring, vomiting, diarrhea, stomach pain, excessive sweating, rashes, joint pain, muscle pain, back pain, muscle spasms, bedwetting, urinary incontinence, and swelling of the limbs.

Symptoms include vomiting, excessive sweating, periods of stopped breathing, seizures, agitation, loss of psychomotor skills, and coma.

[37]: 79 [38] The first extended research into sodium oxybate and its use in humans was conducted in the early 1960s by Henri Laborit to study the neurotransmitter GABA.

[10]: 11–12 [39] It was studied for a range of uses, including obstetric surgery, during childbirth, and as an anxiolytic; there were anecdotal reports of it having antidepressant and aphrodisiac effects as well.

[42][43][44] At the same time, research on the use of sodium oxybate had formalized, as a company called Orphan Medical Inc. had filed an Investigational New Drug application and was running clinical trials with the intention of gaining regulatory approval for use to treat narcolepsy.

[55] In July 2007, Jazz Pharmaceuticals and their subsidiary, Orphan Medical, pleaded guilty to a criminal charge of felony misbranding in their marketing of sodium oxybate; they also settled a civil suit at the same time.

Jazz Pharmaceuticals paid $20 million in total and agreed to a corporate integrity agreement and to implement internal reforms.

[60] In January 2017, the FDA approved the first generic sodium oxybate product for narcolepsy symptoms, which is also subject to the same REMS program conditions as the original.

These government agencies are the sole purchaser (or regulator) of medical goods and services and have the power to set prices.

[69] NHS England authorises and pays for sodium oxybate by means of individual funding requests on the basis of exceptional circumstances.

The British Department of Health pays for the medication for 80 patients who are taking legal action over problems linked to the use of the swine flu vaccine Pandemrix at a cost of £12,000 a year.

The judge criticised their "thoroughly bad decision" and "absurd" policy discriminating against the girl when hundreds of other NHS patients already receive the drug.

[73] As of April 2018, sodium oxybate is sold under the following brands: Alcover (Italy), Gamma-OH (France), Natrii oxybutyras Kalceks (Latvia), Somsanit (Germany), Xyrem (many countries by Jazz Pharmaceuticals and UCB).

The company presented Phase I results in 2015, stating that deuterium-related effects made it necessary to do further formulation work as part of the drug's development.