[​IMG] Gamma-Butyrolactone is an addictive depressant used for its euphoric and sleep inducing effects.

GBL is used to produce the related GHB, but is also consumed on its own. GBL can be synthesized from gamma-hydroxybutyric acid (GHB) by removal of water or by distillation from such a mixture. GHB is a naturally occurring fatty acid found throughout the human body. The inhibitory neurotransmitter gamma-aminobutyric acid (GABA) is the precursor for GHB in human brains. GHB readily crosses the blood-brain barrier with rapid onset of anxiolytic, sedative and euphoric effects. It acts in the central nervous system at the GABABB receptor and the GHB receptor.

GBL is a precursor of GHB and is rapidly converted (half-life approximately 1 minute) to GHB when ingested into the human body in the stomach and blood. It is difficult to distinguish the misuse of GBL with that of GHB as only the latter compound can be detected in body fluids.


GBL is sold as an industrial cleaner (alloy cleaner). It is also present in a number of other products such as nail varnish remover pads. Since it was classified a class C drug many users obtain it from soaking nail polish remover pads. 1,4-butanediol (BD) is another class C and related substance often used by same user group, which is an active analog of GHB, also converting rapidly to GHB in the body.

It has been used as a recreational drug on the club scene for many years and has also been used as a weight gain product by bodybuilders. There is a link of GBL’s use in drug assisted sexual assault in the UK, USA, and Australia although other drugs are more commonly used. GBL mainly replaced the use of GHB after GHB was classified under the Misuse of drugs act in 2003 prior to GBL also being banned in December 2009.


1ml of GBL is equal to 1.6g of GHB and, due to the efficacy of the in-vivo conversion, is delivered more rapidly to the brain.

GBL has a steep dose: response curve so even a small amount can result in accidental overdose. Therefore always start with a small dose: 0.3-0.5mls and wait for effects. If no effects are felt, wait a few hours before re-dosing as the dose is cumulative. Doses should not exceed 1.5ml initially with redosing of 1ml or so at about 45 minute intervals. Always use diluted with water or juice. Remember if it is already diluted it is difficult to know the exact strength of the solution.

If one is aiming to use GBL in place of alcoholic drinks then it is typical to start with a 1-1.5ml starter dose and then drink pints with 0.4-0.5mls of GBL as they would drink alcoholic drinks.

It is very important to properly measure doses of GBL, and due to the mild amnestic effects it is also very wise to write doses on one's had so that they are not forgotten. Proper measurement involves the use of graduated measuring devices as opposed to bottlecaps and other non-standardised devices.


Onset of effects

10-30 minutes

Duration of effects

2-4 hours

Physical effects

  • Central Nervous System (CNS) depression
  • Sedation
  • Restful sleep
  • Increased energy
  • Increased sex drive
  • Dizziness
  • Unconsciousness often referred to as “bleaching”
  • Hot/cold flushes
  • Uncontrolled body movements
  • Impaired coordination
  • Muscle relaxation
  • Vomiting
  • Irritation to skin
  • Enamel erosion
  • Gastro-intestinal irritation
  • Respiratory failure
  • Seizures
  • Hypotension
  • Insomnia
  • Addiction and dependency
  • Can cause unconsciousness, coma or death

Psychological effects

  • Euphoria
  • Emotional intensity
  • Relaxation
  • Loss of inhibition
  • Increased sociability
  • Cravings to re-dose
  • Hallucinations
  • Confusion
  • Agitation
  • Paranoia
  • Anxiety

GBL Dependency and Detoxification

Withdrawal times

Varies depending on a range of factors but is usually between 5-10 days.

Dangers from withdrawal symptoms

As with chronic alcohol addiction, withdrawal from GHB/GBL dependency should be done under medical supervision and preferably on an inpatient basis. It can be dangerous to suddenly stop taking GHB/GBL.

Withdrawal effects are similar to chronic alcohol dependence and benzodiazepine dependence. Symptoms include anxiety, insomnia, tremor, confusion, nausea, vomiting, hypertension and tachycardia. Symptoms can start very quickly, one or two hours after the last dose and may rapidly progress to a state of uncontrolled delirium and agitation. Rhabdomyolysis and seizures have occurred. In such cases, transfer to a medical unit is indicated, and occasionally treatment in ICU may be required.


The recommended treatment is to stabilise symptoms of anxiety and psychotic symptoms. Benzodiazepines (selective GABAA agonists) are useful in ameliorating some of the signs and symptoms of GHB/GBL withdrawal. Loading doses of benzodiazepines do not decrease the likelihood of withdrawal delirium, but are important for controlling agitation. Most patients in GHB/GBL withdrawal have an extremely high tolerance to the sedating effects of benzodiazepines and require large frequent doses greater than those required for the treatment of severe alcohol withdrawal. Use of high-dose benzodiazepines requires prolonged intensive monitoring and is associated with complications. A lack of activation of GABAA receptors by GHB may explain why benzodiazepines may be unsatisfactory. Withdrawal from GHB/GBL has been shown to be a GABAb-mediated effect.. This suggests that baclofen (GABAbagonist) would be effective at replicating many effects of GHB, and thus be a useful adjunctive treatment for GHB/GBL withdrawal. Treatment using oral high-dose chlordiazepoxide and baclofen regimens are being applied in some areas of UK. Other drugs used in treatment of GBL withdrawal (more often outside of the UK) include Gabapentin and Pregabalin.

Pharmacology of GHB

LD50 (ml/kg) :
Rat : 17.2 mL oral

Chemistry of GHB

Column 1 Column 2
Title compound: GBL
Systematic (IUPAC) name: Dihydro-2(3H)-furanone
Synonyms: Butyrolactone, [gamma]-butyrolactone, 1,2-butanolide, [gamma]-hydroxybutyric acid lactone, 3-hydroxybutyric acid lactone, 4-hydroxybutanoic acid lactone
Molecular Formula: C4H6O2
Molar mass: 86.09 g/mol
CAS Registry Number: 96-48-0
Melting Point: -43.53°C
Boiling Point: 204°C @ 760 mmHg, 89°C @ 12 mmHg
Flash Point: 98°C (open cup)
Solubility: miscible with water, soluble in methanol, ethanol, acetone, ether, benzene
Additionnal data: density (15°C) 1.1286
Notes: aspect : oily hygroscopic liquid

Legal Status

In UK, GBL was made a class “C” drug under the Misuse of Drugs Act in December 2009. Possession carries up to 2 years imprisonment and an unlimited fine. Supply carries up to 14 years imprisonment and an unlimited fine.

Harm Reduction Advice

  • Always measure dosage (use dropper) and start with a small dose (0.3-0.5mls).
  • Wait until effects are felt and do not re-dose until at least 2 hours.
  • Do not mix with other sedatives/alcohol
  • Be careful-the strength may be unknown, particularly if already diluted-even a very small amount can result in an overdose
  • Always dilute-and add a food colour to prevent accidental ingestion
  • As it is common for users to become unconscious always use in a safe place with a “straight” friend
  • If a user becomes unconscious place in the recovery position to prevent choking
  • Avoid frequent use to prevent dependency developing

History of GBL


[1] Merck Index, fifteenth edition (2013)
Categories: Depressants, Hydroxybutyrates

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