GHB is used as a general anesthetic in Europe. In the US, the FDA approved GHB for use in the treatment of narcolepsy (a sleep disorder) in 2002. This approval came with severe restrictions, including its use only for the treatment of narcolepsy and the requirement of a patient registry monitored by the FDA.
It has been used in this country as a date rape drug: it can be slipped into a victim's drink, causing dizziness, confusion, drowsiness and sometimes loss of consciousness. When GHB is combined with alcohol, it is especially dangerous because the combination of two depressants can lead to overdose. Before the use of GHB was restricted, it was marketed to bodybuilders as a product to release growth hormone and build muscles. There is no evidence that it produces this effect. GHB was also marketed as an "herbal" supplement to help with sleep and depression.
GHB acts on at least two sites in the brain: a GABA (gamma aminobutyric acid) receptor and a specific GHB binding site. Because GHB is a metabolite of the inhibitory transmitter GABA, it is found naturally in the brain but at concentrations much lower than doses that are abused.