GHB (gamma-hydroxybutyric acid) is a powerful central nervous system depressant that, at low doses, produces euphoria and relaxation, and at higher doses can rapidly cause unconsciousness, respiratory failure, and death. The margin between a dose that makes someone feel intoxicated and one that can kill them is dangerously narrow: blood concentrations of 80 to 100 mg/L cause inebriation, while 300 to 500 mg/L can be fatal.
How GHB Works in the Brain
GHB is actually a substance your brain produces naturally, though in tiny amounts. It exists in human brain tissue at concentrations of just 2 to 20 nanomoles per gram. When someone takes GHB as a drug, the concentrations flooding the brain are orders of magnitude higher than what the body makes on its own.
At these elevated levels, GHB acts primarily on GABA-B receptors, the same system targeted by some muscle relaxants and anti-anxiety drugs. Activating these receptors is what produces sedation, slowed movement, and lowered body temperature. GHB also binds to a specific type of GABA-A receptor found in the forebrain, opening chloride channels that further dampen brain activity. The combined effect is a broad suppression of the central nervous system, which is why the drug can shift so quickly from producing a pleasant buzz to knocking someone unconscious.
What It Feels Like at Different Doses
At low doses, GHB typically produces feelings of euphoria, well-being, and sociability. Users often describe a warm, alcohol-like relaxation with reduced inhibitions. These effects kick in relatively fast, usually within 15 to 30 minutes of swallowing the liquid or powder.
The problem is GHB’s extremely steep dose-response curve. Small increases in the amount taken cause disproportionately larger jumps in toxicity. Moving from a “pleasant” dose to a dangerous one can be a matter of a single milliliter of liquid, depending on concentration. At moderate to high doses, effects shift to nausea, vomiting, loss of coordination, slurred speech, and confusion. At higher doses still, the drug causes loss of consciousness, loss of the gag reflex, dangerously slowed breathing, a drop in heart rate, and hypothermia.
This steep curve is one reason GHB is involved in so many emergency room visits. In clinical case series, there was overlap between the blood concentrations found in patients who were fully awake and those who were in a coma, meaning two people who took seemingly similar amounts can end up in very different medical states.
How Long the Effects Last
GHB has a short elimination half-life, meaning the body processes it quickly. Effects generally peak around 60 to 90 minutes after ingestion and wear off within 3 to 5 hours. Because the drug clears the body so fast, it is also difficult to detect after the fact. In urine, GHB is typically only detectable for about 12 hours, though at least one documented case found it 28 to 29 hours after ingestion in an elderly patient with slower metabolism. In blood, the detection window is even shorter.
This rapid clearance is part of why GHB has been used to facilitate sexual assault. By the time a victim seeks medical attention, the drug may already be undetectable.
Why Mixing GHB With Alcohol Is Especially Dangerous
Alcohol is frequently involved in GHB-related emergencies, and the two drugs together are significantly more dangerous than either one alone. A controlled study in humans found that combining even modest doses of GHB and alcohol produced greater drops in blood oxygen levels than either substance individually. The combination also caused more episodes of vomiting and drops in blood pressure.
The interaction appears to be primarily pharmacodynamic, meaning the two drugs amplify each other’s depressant effects on the brain and respiratory system rather than one dramatically changing how the other is metabolized. Alcohol did produce a 16% higher peak GHB concentration and a 29% longer elimination half-life, though these changes alone don’t fully explain the severity of combined toxicity. The real danger is that both drugs suppress breathing through overlapping mechanisms, and together they can push respiratory depression past the point of survival.
Long-Term Cognitive Effects
Occasional low-dose GHB use appears to cause short-term cognitive impairment that resolves once the drug clears the system. Chronic heavy use, however, tells a different story. A systematic review in Current Neuropharmacology found that regular high-dose GHB use, particularly when it involves repeated GHB-induced comas, is likely neurotoxic and produces lasting cognitive damage.
Heavy users who had experienced multiple GHB-induced comas performed worst on verbal memory tests and reported higher levels of anxiety, stress, depression, and impulsivity. Brain imaging showed these individuals had a reduced capacity to interpret and store new memories, difficulty maintaining focus when tasks required distinguishing between competing information, and problems reading negative emotions in others. These changes corresponded to structural differences in the hippocampus (critical for memory) and prefrontal cortex (involved in attention and decision-making).
Even moderate GHB use without coma episodes was associated with altered connectivity between brain regions involved in emotional processing and rest states. No follow-up studies have tracked whether these cognitive deficits reverse after people stop using GHB, so it remains unclear how permanent the damage is.
Dependence and Withdrawal
GHB is physically addictive with regular use, and withdrawal can be severe. The most common symptoms include intense cravings, fatigue, insomnia, tremors, sweating, and sudden swings between feeling cold and hot. More serious withdrawal can involve hallucinations, psychosis, and delirium.
The withdrawal timeline follows a pattern where the most physically uncomfortable symptoms peak in the first three days. Muscle aches, racing heart, abdominal cramps, shivers, and goosebumps typically drop by more than 70% in severity over the first four days of detoxification. Other symptoms, however, are more stubborn. Tremors, shaking hands, disrupted sleep, and restlessness showed less than 25% improvement over an 11-day monitored tapering period. Cravings and insomnia were commonly still present at the time patients were discharged from detox programs.
GHB withdrawal can be medically dangerous and, in severe cases, life-threatening. People who have been using GHB multiple times per day, especially around the clock, face the highest risk of serious withdrawal complications.
Medical Use Under Prescription
Pharmaceutical GHB, sold as sodium oxybate, is FDA-approved for treating narcolepsy. Specifically, it is prescribed for cataplexy (sudden muscle weakness triggered by emotions) and excessive daytime sleepiness in adults with narcolepsy. The prescribed starting dose is 4.5 grams taken once at night, gradually increased to a range of 6 to 9 grams. This use is tightly controlled through restricted distribution programs because of the drug’s abuse potential and the risks of respiratory depression at higher doses.
Under medical supervision at controlled doses, cognitive impairment has not been demonstrated. The cognitive damage seen in research is associated with uncontrolled recreational use, particularly the repeated cycles of overdose and coma that heavy users experience.