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    GBL molecular structure

    GBL Stats & Data

    Depressant
    Gamma-bl Blue nitro Revivarant Renewtrient 1,4-lactone
    Psychoactive Class Depressant
    Half-Life GBL is converted to GHB very rapidly (on the order of minutes); GHB elimination half‑life is commonly cited around 30–60 minutes, but clinical effects can outlast plasma levels due to receptor dynamics and stacking.

    Interaction Warnings

    ⚠ dissociatives

    This combination can result in an increased risk of vomiting during unconsciousness and death from the resulting suffocation. If this occurs, users should attempt to fall asleep in the recovery position or have a friend move them into it.

    ⚠ stimulants

    It is dangerous to combine GBL, a depressant, with stimulants due to the risk of excessive intoxication. Stimulants decrease the sedative effect of GBL, which is the main factor most people consider when determining their level of intoxication. Once the stimulant wears off, the effects of GHB will be significantly increased, leading to intensified disinhibition as well as other effects. If combined, one should strictly limit themselves to only dosing a certain amount of GHB per hour.

    Pharmacology

    DrugBank
    State Solid

    Description

    One of the furans with a carbonyl thereby forming a cyclic lactone. It is an endogenous compound made from gamma-aminobutyrate and is the precursor of gamma-hydroxybutyrate. It is also used as a pharmacological agent and solvent.

    Mechanism of Action

    GBL is a rapidly- and short-acting prodrug to GHB with an uneven conversion rate into the same. (1g GHB = 1.6 ml GBL)

    Pharmacodynamics

    GBL can be converted to GHB prior to ingestion with a strong base, or after ingestion via blood lactonases.

    Toxicity

    Toxicological effects of GHB, and its prodrugs GBL and 1,4-BD, include sedation, hypothermia, respiratory depression, and fatality, and can be attributed to agonism at GABAB receptors.

    Receptor Profile

    Receptor Actions

    Agonists
    Gamma-hydroxybutyrate (GHB) receptor agonist
    GABA-B receptor agonist (via conversion to GHB)

    History & Culture

    GBL has a long history as an industrial chemical, primarily valued as a solvent and intermediate in the synthesis of other compounds. Its commercial applications have included use as a flavoring agent, stain remover, wheel cleaner, paint stripper, superglue remover, and as a solvent in certain wet aluminum electrolytic capacitors. The recreational history of GBL is closely intertwined with the scheduling of GHB. Following restrictions placed on GHB, GBL was marketed as a nutritional supplement under brand names such as Revivarant and Renewtrient, capitalizing on its property as a GHB prodrug that enhances sleep-related growth hormone secretion. These products were eventually prohibited by the FDA. In response to tightening regulations on both substances, home synthesis kits emerged that enabled users to convert GBL and 1,4-butanediol into GHB, effectively circumventing restrictions on the scheduled substance. The relative accessibility of GBL's precursors has contributed to its popularity in certain recreational contexts, particularly among young people in French nightclub scenes where it can be produced with readily available materials. Both GBL and GHB are colloquially referred to as "K.-o.-Tropfen" (knockout drops) in German-speaking countries. While concerns have been raised regarding the potential use of GBL as a drug-facilitated sexual assault agent—particularly as an alternative to scheduled GHB—the available evidence suggests such use is not widespread, especially when compared to alcohol, partly due to GBL's distinctively strong taste.

    Subjective Effect Notes

    physical: The physical effects of GBL can be broken down into several components which progressively intensify proportional to dosage.

    cognitive: The cognitive effects of GBL can be broken down into several components which progressively intensify proportional to dosage.

    Community Effects

    TripSit
    Positive
    relaxation

    Tolerance & Pharmacokinetics

    drugs.wiki
    Half-Life
    GBL is converted to GHB very rapidly (on the order of minutes); GHB elimination half‑life is commonly cited around 30–60 minutes, but clinical effects can outlast plasma levels due to receptor dynamics and stacking.
    Addiction Potential
    High with frequent use: tolerance can build in days; physical dependence and medically dangerous withdrawal have been repeatedly documented, especially with around‑the‑clock redosing patterns.

    Tolerance Decay

    Full tolerance 1d Half tolerance 3d Baseline ~7d

    Tolerance builds rapidly with frequent redosing (days). After cessation, many users report substantial reduction within 3–7 days and near‑baseline in 1–2 weeks; heavy, prolonged use may prolong recovery. Cross‑tolerance is expected across GHB prodrugs. Data derive largely from HR orgs and user reports; interindividual variability is high.

    Cross-Tolerances

    GHB
    80% ●●○
    1,4-Butanediol
    80% ●○○

    Experience Report Analysis

    Erowid
    80 Reports
    1997–2022 Date Range
    24 With Age Data
    31 Effects Detected

    Demographics

    Gender Distribution

    Age Distribution

    Reports Over Time

    Effect Analysis

    Erowid

    Effects aggregated from 80 experience reports (80 Erowid)

    80 Reports
    31 Effects Detected
    12 Positive
    12 Adverse
    7 Neutral

    Effect Sentiment Distribution

    Confidence Distribution

    Positive Effects 12

    Anxiety Suppression 46.2% 70%
    Euphoria 41.2% 70%
    Stimulation 41.2% 70%
    Tactile Enhancement 30.0% 70%
    Empathy 26.2% 70%
    Music Enhancement 22.5% 70%
    Focus Enhancement 18.8% 70%
    Sedation 17.5% 70%
    Color Enhancement 12.5% 70%
    Body High 8.8% 70%
    Introspection 7.5% 70%
    Creativity Enhancement 5.0% 70%

    Adverse Effects 12

    Confusion 26.2% 70%
    Nausea 26.2% 70%
    Sweating 12.5% 70%
    Increased Heart Rate 11.2% 70%
    Psychosis 7.5% 70%
    Seizure 7.5% 70%
    Memory Suppression 6.2% 70%
    Headache 6.2% 70%
    Motor Impairment 5.0% 70%
    Muscle Tension 5.0% 70%
    Appetite Suppression 3.8% 70%
    Jaw Clenching 3.8% 70%

    Dosage Distribution

    Dose distribution from experience reports

    Median: 2.2 ml IQR: 1.5–6.0 ml n=23

    Real-World Dose Distribution

    62K Doses

    From 71 individual dose entries

    Oral (n=8)

    Median: 2000.0mg 25th: 1225.0mg 75th: 2000.0mg 90th: 2180.0mg
    mg/kg median: 26.722 mg/kg 75th: 33.333

    Common Combinations

    Most co-occurring substances in experience reports

    Form / Preparation

    Most common forms and preparations reported

    Body-Weight Dosing

    Dose relative to body weight from reports with weight data

    Median: 0.033 mg/kg IQR: 0.018–0.078 mg/kg n=25

    Redose Patterns

    Redosing behavior across 65 reports

    10.8% Redosed
    1.2 Avg Doses
    27m Median Interval
    Read full reports on Erowid →

    Legal Status

    Country Status Notes
    Australia Border Controlled Substance Illegal to import without a permit. Importation of a commercial quantity (over 1 kg) is punishable by up to life imprisonment and/or an AUD $825,000 fine.
    Austria Illegal (NPSG) Since January 1, 2012, possession, production, and sale are prohibited under the Neue-Psychoaktive-Substanzen-Gesetz (New Psychoactive Substances Act).
    Canada Schedule VI (CDSA) Controlled under Schedule VI of the Controlled Drugs and Substances Act. Vendors must collect purchase information. Import and export are prohibited, punishable as an indictable offence (up to 10 years) or summary conviction (up to 18 months). Personal possession is not illegal.
    Germany Controlled Distribution Not listed in the Betäubungsmittelgesetz (Narcotics Act), but distribution is controlled. Possession is not illegal unless intended for human consumption or GHB synthesis, in which case the Arzneimittelgesetz (Medicines Act) may apply.
    Hong Kong Schedule 1 (Dangerous Drugs Ordinance) Controlled as a dangerous drug under Schedule 1 of the Dangerous Drugs Ordinance, Cap.134, with exemption clause at Paragraph 16D. Unauthorized possession punishable by a fine of HK$1,000,000 and imprisonment for 7 years upon indictment.
    Israel Proscribed Substance Classified as a proscribed substance since 2007. Possession, production, and distribution are prohibited under national drug control legislation.
    Netherlands Legal (Industrial Use) Freely available as a cleaning agent. Retailers do not require a license to sell the substance for legitimate industrial purposes.
    Poland Controlled Drug Classified as a drug under national pharmaceutical legislation. Handling requires a pharmaceutical license; unauthorized possession and distribution are prohibited.
    Sweden Health-Endangering Substance Not classified as a narcotic drug but designated a health-endangering substance. Legislation enacted in April 2011 enabled GBL to be treated as a controlled substance when not used for legitimate industrial purposes.
    Switzerland Illegal (GHB Analog) Considered an ester analog of GHB, making it controlled under Buchstabe B of Swiss narcotics legislation. Industrial use remains permitted with appropriate authorization.
    Turkey Illegal Classified as a controlled drug. Possession, production, supply, and importation are prohibited under national drug legislation.
    United Kingdom Conditionally Controlled Under Regulation 4B of the Misuse of Drugs Regulations 2001, it is lawful to import, export, produce, supply, or possess GBL for legitimate purposes. The substance becomes controlled when a person handles it knowing or believing it will be used for human ingestion.
    United States List I Controlled Chemical Regulated as a List I controlled chemical under federal law. As a GHB analog, it is treated as a Schedule I controlled substance under the Controlled Substances Act when intended for human consumption.

    Harm Reduction

    drugs.wiki

    GBL is a prodrug rapidly converted to GHB in vivo; relative to GHB it is more potent by volume and has a faster, sharper onset, which increases overdose risk from small mismeasurements. GBL is a skin/mucosal irritant solvent; always dilute in a non‑alcoholic drink before swallowing, avoid contact with eyes/skin, and never inject or insufflate. The dose‑response curve is steep: recreational doses lie close to doses causing unrousable sleep and, at higher levels or when mixed with other depressants, life‑threatening respiratory depression. Redosing too soon causes stacking: wait at least 2 hours between doses and reduce any redose; dopamine‑rebound wakefulness 3–5 hours later can create a strong compulsion to redose but increases risk of dependence. Food reduces/slow s absorption; many HR groups suggest dosing at least 2 hours after eating and avoiding further redose until effects fully plateau. Never combine with alcohol, benzodiazepines, opioids, barbiturates, Z‑drugs, or other depressants; ketamine with G markedly increases loss of consciousness and breathing problems. If someone becomes unrousable, place them in the recovery position, keep airway clear, monitor breathing, and seek emergency help; do not ‘wake’ them with stimulants or give more substances. Tolerance can develop in days with frequent use; withdrawal may begin within 1–6 hours after the last dose and can escalate to agitation, delirium, tachycardia, and life‑threatening complications — medical supervision is essential for dependent users. Concentration varies by source and bottles; unknown dilution is common — start low (0.3–0.5 mL), measure precisely to 0.1 mL, and label doses/times to avoid mistakes. GHB/GBL may reduce efficacy of some HIV medications; avoid co‑use and consult a clinician if on antiretrovirals. As a solvent, GBL can degrade some plastics; prefer glass (or chemically resistant equipment) for storage/measurement, clearly label, add a food‑safe dye to avoid accidental ingestion, and keep locked away from children/pets. Do not drive or operate machinery; some HR groups advise waiting at least 24 hours after last dose before driving due to residual impairment and stacking.

    References

    Data Sources

    Cited References

    Drugs.wiki References

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