Gamma hydroxybutyrate toxicity


  • Abbreviation: GHB
  • Frequently referred to as the "date rape drug"
  • Central nervous system depressant
  • GABA-B agonist (as opposed to GABA-A agonists - alcohol, benzodiazepines, etc)
  • Abused for:
    • Body building or sleep enhancement
    • euphoric, sexual, stimulant, and relaxant effects
    • Surreptitious drugging to facilitate sexual assault
  • Also used therapeutically in the treatment of narcolepsy[1]


  • Effects start in 15-20 minutes, peak in 30-60 minutes,
  • Lipid soluble, readily crosses the blood brain barrier
  • Elimination is dose-dependent; half-life of 20-50 minutes
  • The duration of GHB's clinical effects depends upon the dose, and ranges from 2.5-4 hours


  • Is a metabolite and precursor of GABA
  • Interacts with GHB-specific receptors and also acts as a direct agonist of GABA-B receptors
  • Affects multiple neurotransmitter systems, including those of opioids, dopamine, serotonin, glutamate, and acetylcholine
  • Gamma butyrolactone (GBL) and 1,4 butanediol (BD) are GHB analogs that are rapidly metabolized to GHB after ingestion, with the same toxic and recreational effects

Clinical Features

Classic Presentation: Young adult presents comatose and is intubated for airway protection and subsequently awakens while in the emergency department. When awake, typically can be safely discharged.

  • CNS depression; ataxia, nystagmus, somnolence, seizure, coma
    • EEG may show no epileptiform changes
  • Respiratory depression; may also alternate between periods of apnea and hyperventilation
  • Bradycardia, hypotension; ECG changes are rare
  • Nausea and vomiting GI symptoms
  • Hypothermia
  • Often found to have co-intoxicants
  • Usually young white male from nightclub
  • CNS and respiratory depression can resolve abruptly within minutes
    • Patients may become aggressive upon waking

Clinical Course

  • Recover in 2-6 hours
  • May be extubated and sent home
  • If longer than 6 hours, look for other cause
  • Can have cross tolerance with other drugs-alcohol and others that effect liver p450 cytochrome oxidase system

Differential Diagnosis

Sedative/hypnotic toxicity

Drugs of abuse


  • Not detectable on rapid urine drug screens
  • Definitive diagnosis requires gas chromatography
  • ED physicians are not accurate in diagnosing clinically


  • Supportive
  • Look for co-ingestants and occult trauma
  • Charcoal not helpful since rapidly absorbed; patients may vomit and are at risk for aspiration
  • Protein bound so can use dialysis but so short course usually do not need.



  • May consider discharge if symptoms improve after observation for several hours
  • Consider admission if symptoms do not improve or worsen

See Also


  1. Mamelak M, Scharf MB, Woods M. Treatment of narcolepsy with gamma-hydroxybutyrate. A review of clinical and sleep laboratory findings. Sleep. 1986;9(1 Pt 2):285-289. doi:10.1093/sleep/9.1.285