γ-Hydroxybutyric acid (GHB), also known as 4-hydroxybutanoic acid and sodium oxybate (INN), is a naturally occurring substance found in the human central nervous system, as well as in wine, beef, small citrus fruits, and almost all animals in small amounts. It is also categorized as an illegal drug in many countries. It is currently regulated in Australia and New Zealand, Canada, most of Europe and in the US. GHB as the sodium salt, known as sodium oxybate, is sold by Jazz Pharmaceuticals under the name Xyrem to treat cataplexy and excessive daytime sleepiness in patients with narcolepsy.
GHB has been used in a medical setting as a general anesthetic, to treat conditions such as insomnia, clinical depression, narcolepsy, and alcoholism, and to improve athletic performance. It is also used as an intoxicant (illegally in many jurisdictions) or as a date rape drug. GHB is naturally produced in the human body's cells and is structurally related to the ketone body beta-hydroxybutyrate. As a supplement/drug, it is used most commonly in the form of a salt, for example sodium gamma-hydroxybutyrate (Na.GHB, sodium oxybate, or under the brand name Xyrem.) or potassium gamma-hydroxybutyrate (K.GHB, potassium oxybate). GHB is also produced as a result of fermentation, and so is found in small quantities in some beers and wines. Succinic semialdehyde dehydrogenase deficiency is a disease that causes GHB to accumulate in the blood.