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PLUGGUIDE
GHB / GBL — hero

Depressant · gaba-precursor

GHB / GBL

aka Gamma-hydroxybutyrate · Gamma-butyrolactone · G · Liquid X · Liquid Ecstasy · Goop · Fantasy · 1,4-BD

Last verified

GHB (gamma-hydroxybutyrate) is a naturally occurring neurotransmitter and a powerful CNS depressant. It is clinically used as sodium oxybate (Xyrem) for narcolepsy and was the subject of one of the more notorious recreational drug arcs of the late 1990s and 2000s — popular in nightclub and chemsex scenes for its short-acting, euphoric, disinhibitory profile. GBL (gamma-butyrolactone) is its industrial precursor and converts to GHB in the liver within minutes; 1,4-butanediol (1,4-BD) is another precursor with the same end result. All three are typically called "G" in user contexts.

The defining feature of GHB is the dose-response curve. The difference between a "common" recreational dose and an "unconscious overdose" dose is small — often just a few hundred milligrams. Variability in product strength (especially with GBL, which is 1.6x more potent than GHB by volume) and inaccurate dosing methods (eyeballing instead of syringe-measuring) cause routine overdoses even in experienced users. Combined with alcohol the curve becomes still steeper, which is why alcohol is involved in the majority of GHB-related deaths.

The other defining feature is the addiction pattern. Daily users typically dose every 2-3 hours around the clock, including waking up at night to redose, because the duration is so short and the inter-dose anxiety is significant. Physical dependence can develop in weeks. GHB withdrawal is one of the most dangerous drug withdrawals known — comparable to severe alcohol or benzodiazepine withdrawal, with delirium, autonomic instability and seizure risk. Heavy chronic users typically need hospital-supervised detox.

GHB is also one of the substances most associated with drug-facilitated sexual assault: colourless, fast-acting, near-tasteless in sweet drinks, and producing amnesia at higher doses. Both contexts — recreational and assault — are relevant to anyone who might encounter it.

Harm reduction

  • Measure with a syringe. Eyeballing GHB or GBL is how experienced users end up in hospital. A 1 mL oral syringe is the right tool. Never use the cap or a "splash from the bottle".
  • Know your product. GHB and GBL look identical but GBL is 1.6x more potent. Switching from one to the other without recalculating is a common cause of overdose. GBL tastes strongly chemical and burns the mouth; GHB tastes salty/soapy.
  • Wait two hours between doses. Onset can be delayed by a full stomach. Stacking doses on the come-up is the most common path to "going under".
  • Never with alcohol. This is the single most dangerous combination and the cause of most GHB-involved deaths. If G is on the table, alcohol is off it.
  • Never with other depressants. Benzos, opioids, ketamine, barbiturates, gabapentinoids — all stack catastrophically with GHB respiratory depression.
  • Have a sober person present at any session, particularly in chemsex contexts where dose tracking gets lost in long sessions. They should know what "going under" looks like and when to call an ambulance.
  • If a friend goes under: recovery position immediately (on side, head tilted down), monitor breathing, call emergency services. Do not assume they will wake up safely. Vomiting while unconscious causes aspiration.
  • Don't quit cold-turkey if you're a daily user. GHB withdrawal can kill. Hospital-supervised detox using high-dose benzodiazepines or baclofen is the standard medical approach.
  • For chemsex contexts: thechemsexsupport.uk and equivalent EU services provide non-judgmental harm reduction tailored to this scene.

Dosage.

Oral
Threshold
0.5 g
Light
0.5–1 g
Common
1–2.5 g
Strong
2.5–4 g
Heavy
4 g

Start at the bottom. Body chemistry, tolerance, and combinations all matter.

Duration.

Oral

total ~ 510 min
Onset: 10–30 minPeak: 45–90 minOffset: 1.5–2.5hAfter: 2–4h
Onset
10–30 min
Peak
45–90 min
Offset
1.5–2.5h
After
2–4h

Effects.

Positive

  • Euphoria and "warm" body high
  • Strong disinhibition and increased sociability
  • Increased libido and tactile sensitivity
  • Anxiolysis and muscle relaxation
  • Mild stimulation at lower doses (paradoxical)

Neutral

  • Dizziness and slight motor impairment
  • Drowsiness building toward sleep
  • Nausea, especially on a full stomach or with alcohol
  • Mild euphoric "drunk" feeling

Negative

  • Catastrophically steep dose-response curve: a small overdose causes unconsciousness; a slightly larger one causes respiratory arrest
  • Sudden unconsciousness ("going under") with no warning
  • Vomiting while unconscious leading to aspiration and death
  • Severe physical dependence with frequent dosing (every 2-4 hours around the clock)
  • GHB withdrawal can be fatal — comparable to severe alcohol or benzo withdrawal
  • Common date-rape drug due to colourless, near-tasteless liquid form

Interactions.

Heads up

Many drug combinations are unsafe even at low doses. When in doubt, take less or abstain. Always cross-check with the interaction checker tool.
Dangerous

Combination may cause serious harm. Avoid.

  • alcohol
  • opioids
  • benzodiazepines
  • ketamine
  • barbiturates
  • gabapentinoids
  • other-depressants
Unsafe

Substantial risk. Combination not recommended.

  • mdma
  • amphetamine
  • cocaine
  • dxm
Caution

Mild interaction. Use with reduced doses.

  • cannabis
  • psychedelics
  • ssris

Testing.

  • ReagentGhb-test-stripExpected reactionAvailable from harm-reduction services and online vendors. Useful for testing drinks for spiking. Does not measure dose or distinguish GHB from GBL.
  • ReagentMarquisExpected reactionNo reaction
  • ReagentMeckeExpected reactionNo reaction
  • ReagentMandelinExpected reactionNo reaction
  • ReagentTaste-testExpected reactionGHB tastes salty/soapy; GBL tastes strongly chemical and burns the mouth. Neither test is safe or reliable but recognising the burn of GBL can prevent accidental overdose from a "GHB" dose that's actually GBL.

Cross-check with a secondary reagent. Tests tell you what something isn't, not always what it is.

Harm reduction

FAQ.

What's the difference between GHB and GBL?
GBL (gamma-butyrolactone) is the industrial precursor that converts to GHB in the liver within minutes of ingestion. It is roughly 1.6x more potent than GHB by volume. The subjective experience is essentially identical once GBL has converted. The key danger is dose confusion — if a user dosing in "GHB millilitres" suddenly switches to GBL without recalculating, an unintentional overdose is almost guaranteed. 1,4-butanediol (1,4-BD) is another precursor that also converts to GHB in the body.
How long does GHB last?
Onset 10-30 minutes (faster on an empty stomach), peak 45-90 minutes after dosing, total duration roughly 2-3 hours. The short duration is what drives the dependence-forming dosing pattern — users redose every 2-4 hours to maintain effects, and physical dependence develops with around-the-clock dosing.
Why is GHB so dangerous?
Two reasons. First, the dose-response curve is extremely steep — the difference between a fun social dose and an unconscious overdose is often a few hundred milligrams. Second, it stacks catastrophically with other depressants. GHB plus alcohol is the most common scenario in GHB-involved deaths. The unconscious overdose state ("going under") looks deceptively like sleep but the airway is compromised and vomiting can cause fatal aspiration.
Can you overdose on GHB alone?
Yes, easily. Pure GHB overdose presents as unconsciousness, slow breathing, occasional seizure activity and vomiting. Without intervention the user can stop breathing or aspirate vomit. The combination with alcohol or other depressants makes overdose substantially more likely at lower doses. There is no specific antidote — supportive care, airway management and recovery position are the treatment.
Is GHB addictive?
Severely. Daily users typically dose every 2-3 hours around the clock, including waking up at night to redose. Physical dependence can develop within weeks of this pattern. GHB withdrawal is one of the most dangerous drug withdrawals — comparable to severe alcohol or benzo withdrawal, with risk of delirium, seizures, severe autonomic instability and death. Heavy chronic users should be tapered or detoxed in a hospital setting.
How much GHB should I take?
For someone naive to GHB and confident in their source's purity, 1 g is a typical "common" starting dose. Wait at least 2 hours before considering redosing — onset can be delayed, particularly on a full stomach, and stacking doses on the come-up is the most common path to unintentional overdose. Use a syringe or accurate medicine cup for liquid dosing; eyeballing is how people end up in hospital.
Is GHB the same as the date-rape drug?
GHB is one of the substances most associated with drug-facilitated sexual assault. It is colourless, near-tasteless when mixed with sweet drinks, fast-acting, and produces amnesia at higher doses. Drink-spike test strips exist and detect GHB in some commercial drinks. Standard advice for any social setting where GHB might be present: keep your drink with you, don't accept open drinks from strangers, and watch out for friends who suddenly become very intoxicated without much alcohol.
Can I mix GHB with alcohol?
This is the single most dangerous GHB combination and the cause of most GHB-involved deaths. Alcohol potentiates GHB's CNS depression and respiratory depression non-linearly. Doses that would be fine sober become unconscious overdoses with alcohol on board. The disinhibition of both drugs also leads to redosing while already heavily intoxicated. If GHB is on the table, alcohol should be off it.
What does going under feel like?
"Going under" is the GHB term for unconsciousness from an overdose. Onset is sudden — people describe a few minutes of increasing drowsiness, then loss of consciousness with no clear warning. The user may snore, twitch or vomit; they cannot be roused. From the outside it looks like deep sleep, which is why bystanders often don't call emergency services. They should. Recovery position, monitor breathing, call an ambulance. Most users recover fully in 2-4 hours, but the period of unconsciousness is high-risk for aspiration.
How long does GHB stay in your system?
GHB itself is detectable in urine for only about 8-12 hours and in blood for 4-8 hours — much shorter than most drugs. This makes it difficult to detect in suspected drug-facilitated assault if testing is delayed. Standard 5-panel and 10-panel workplace drug tests do not screen for GHB. Specific GHB tests exist but are not routinely run.

Related tools.

ToolDosage calculatorToolInteraction checkerToolReagent guide

Sources.

  1. 01PsychonautWiki: GHB
  2. 02PsychonautWiki: GBL
  3. 03TripSit factsheet: GHB
  4. 04EMCDDA — GHB and GBL profile
  5. 05BMJ Open: GHB withdrawal treatment review