1,3-Butanediol
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1,3-Butanediol (butane-1,3-diol) is a synthetic depressant of the aliphatic diol class. It is a structural cousin of 1,4-butanediol — a compound that converts to GHB — but takes a different metabolic route. The liver converts it into β-hydroxybutyrate, a natural ketone body, which drives its depressant effects.[1]
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Its psychoactive properties were first documented in 1976, when researchers showed it could suppress alcohol withdrawal in rats.[2] DARPA-funded research later incorporated it into ketone formulations designed to improve endurance.[3] Since around 2019, the (R)-form has been commercially sold in "alcohol alternative" beverages aimed at social drinkers.
Subjective effects include lowered inhibitions, reduced anxiety, euphoria, dizziness, and sedation. The experience closely resembles ethanol — relaxation and social ease — but without alcohol's stimulatory early phase and compressed into roughly half its duration.[4][5] Gastrointestinal distress, including nausea and cramping, is the most common unwanted effect and typically limits the dose.
Animal studies show chronic use produces physical dependence and alcohol-like withdrawal;[4] acute toxicity is roughly 2.5 times lower than ethanol in animal models.[6] The compound lowers blood sugar — a meaningful added risk for people with diabetes or on glucose-lowering medications.[7] No controlled human intoxication studies or overdose case reports exist; the safety picture comes almost entirely from animal models.
History[edit]
Discovery
1,3-Butanediol has been commercially available as an industrial solvent and food ingredient since at least the mid-20th century.[8] A controlled human study in 1975 established it as a non-toxic caloric source that lowered blood glucose, opening interest in it as an alternative energy substrate.[7]
Pharmacological investigation
In 1976, Majchrowicz and colleagues showed in Science that 1,3-butanediol could suppress alcohol withdrawal in rats, establishing it as a CNS depressant with cross-tolerance to alcohol.[2] A 1981 study found it roughly equipotent to ethanol in behavioral terms, but a 1983 follow-up confirmed that direct brain injection produced no effect — meaning its CNS action requires metabolic conversion in the liver, not direct receptor binding.[4][1]
Commercial emergence
DARPA-funded research incorporated 1,3-butanediol into ketone ester formulations aimed at improving soldier endurance.[3] From approximately 2019, the (R)-enantiomer appeared in commercial beverages marketed as alcohol alternatives — including KetoneAid Hard Ketones and Avela™ — positioned as social intoxicants with claimed reduced hangover risk. As of 2026, the compound's recreational pharmacology has yet to be formally characterized in controlled human studies.
The name "1,3-butanediol" describes its structure: a four-carbon (butane) backbone with two hydroxyl groups (diol) at the 1- and 3-positions. The abbreviation 1,3-BD is standard in pharmacological literature. Commercial products use the designation (R)-1,3-butanediol or the brand term "Hard Ketones," and are marketed simultaneously to biohackers as a metabolic supplement and to social drinkers as a legal alcohol replacement.
Chemistry[edit]
1,3-Butanediol belongs to the aliphatic diol family — organic compounds with two hydroxyl groups on a simple, saturated carbon chain. Its molecular formula is C₄H₁₀O₂.[9]
It is a structural isomer of 1,4-butanediol, with the same atoms arranged differently: this positional difference determines the pharmacological outcome — 1,4-butanediol converts to GHB and is controlled in many countries, while 1,3-butanediol converts to β-hydroxybutyrate and remains unscheduled.[4]
Pharmacology[edit]
Mechanism of action
1,3-Butanediol is a prodrug — it has no direct effect on brain receptors. The liver converts it into β-hydroxybutyrate (BHB), the primary active metabolite, which then acts through several downstream pathways.[6][10] Direct brain injection of 1,3-butanediol produces no effect, confirming that CNS activity requires metabolic conversion — not direct receptor binding.[1]
Classification disputes
Several pharmacological classifications attributed to 1,3-butanediol in reference databases are unverified or incorrect:
- GABA-A positive allosteric modulator — No direct binding data exist. Central GABA receptor sites are not the compound's site of action.[1] This classification is unverified for the parent compound.
- GHB receptor agonist — 1,3-Butanediol does not convert to GHB. This pathway applies to 1,4-butanediol, a different isomer.[4] This classification is very likely incorrect.
- NMDA receptor antagonist — No published evidence supports this classification. Unverified.
Pharmacokinetics
At a recreational-range dose of 34.5 g taken in split servings, blood BHB peaks around 2.25 hours after dosing and elevated levels persist for up to five hours.[11] At lower doses, BHB rises more modestly and subsides within 1–2 hours.[12][13] Females show greater BHB exposure than males at equivalent doses,[11] producing stronger and longer-lasting effects.
The effects likely unfold in two overlapping phases: an early period of direct alcohol-like sedation as the parent compound enters the brain, followed by a longer BHB-driven phase. The relative contributions of these phases to the subjective experience remain uncharacterized.
Neuroscience[edit]
Where it acts
1,3-Butanediol suppresses brain activity through a mechanism that is not fully understood but is demonstrably distinct from direct GABA receptor activation.[1] In animal models, it impairs motor coordination, reduces anxiety, and produces a behavioral profile that closely parallels ethanol — but at lower brain concentrations.[4]
Why it matters
The leading explanation is metabolic: BHB displaces glucose as a brain fuel, which may alter neurotransmitter production, energy availability at synapses, and neuronal excitability.[14][15] This may explain why ketone supplementation tends to dampen rather than amplify the effects of alcohol. One study also found that the parent compound produces distinct brain metabolic changes that BHB infusion alone cannot replicate — suggesting 1,3-butanediol may have independent central effects beyond its role as a BHB precursor.[16]
No receptor binding characterization has been performed for 1,3-butanediol, so the molecular target of its direct CNS depression is unknown. Whether BHB generated inside the brain contributes meaningfully to its effects — as distinct from BHB arriving through the bloodstream — remains unresolved.[16] Females show greater total BHB exposure than males at equivalent doses,[11] and no explanation for this difference has been established.
Subjective Effects[edit]
The 1,3-butanediol experience is a quiet, contained intoxication — warm disinhibition and relaxed social ease that arrives without the charged energy of alcohol's early phase. The overall character is smooth and rounded, without the sharp edges of a typical drinking session.
Compared to ethanol, 1,3-butanediol is similar in kind but shorter in duration and softer in onset.[4][5] It lacks alcohol's stimulatory opening and tends to produce a cleaner, more contained experience. Gastrointestinal discomfort is more prominent than with alcohol.
Effect Grid
At common doses (~0.35–0.5 g/kg oral, approximately 25–35 g for a 70 kg person), the full alcohol-like intoxication profile emerges. Disinhibition, relaxation, and euphoria are clearly present. Anxiety suppression is pronounced. Dizziness becomes noticeable. Thought deceleration and mild analysis suppression are reported at this level.
Gastrointestinal symptoms (nausea, abdominal cramping) are common and dose-limiting, particularly with rapid consumption. Divided dosing over 30–60 minutes substantially reduces GI distress. Consuming with food improves tolerability.
Subjective effects last approximately 2–3 hours, notably shorter than ethanol at equivalent intoxication levels. Motor coordination is impaired. Driving and operation of machinery are unsafe.
Modeled from the effect's dose-dependence curve — not per-substance measurements.
Sleep-transition hallucinations · Visual acuity suppression · Visual haze / noise · Visual processing suppression
Bodily heaviness · Nystagmus (eye wobbles) · Physical fatigue · Dehydration sensation · Dry mouth · Headache · Laughter fits · Nausea · Pain suppression · Tactile euphoria · Appetite suppression · Stimulation · Body schema distortion · Breathing alteration · Increased urination · Sexual arousal enhancement · Vomiting · Bodily dissociation
Dry mouth · Headache · Laughter fits · Nausea · Pain suppression · Tactile euphoria · Appetite suppression · Stimulation · Body schema distortion · Breathing alteration · Increased urination · Sexual arousal enhancement · Vomiting · Bodily dissociation
Cognitive euphoria · Analysis suppression · Thought deceleration · Cognitive fatigue · Language suppression · Compulsive redosing urge · Confusion · Memory fragmentation · Memory suppression · Motivation suppression · Thought disorganization · Humor enhancement · Delusions of sobriety · Amnesia · Delirium
Cognitive fatigue · Language suppression · Confusion · Memory fragmentation · Memory suppression · Motivation suppression · Thought disorganization · Humor enhancement · Delusions of sobriety · Amnesia · Delirium
Sociability enhancement · Communication enhancement · Depersonalization · Derealization · Cognitive disconnection
Cognitive disconnection
Timeline
First perceptible effects emerge as a subtle warmth or mild relaxation. Gastrointestinal awareness may precede psychoactive onset. BHB elevation begins ~30 minutes post-ingestion.
Alcohol-like relaxation builds progressively. Mild disinhibition and mood elevation become noticeable. GI discomfort, if present, typically peaks during this phase.
Maximum subjective intoxication: euphoria, disinhibition, dizziness, and anxiety suppression are most pronounced. Motor coordination is impaired. BHB Cmax occurs approximately 2 hours post-dose.
Effects diminish more rapidly than ethanol at comparable intoxication levels. Residual relaxation and mild cognitive slowing may persist. GI symptoms typically resolve during this phase.
Residual metabolic effects from elevated BHB may include mild fatigue or altered appetite. Hypoglycemia risk persists in susceptible individuals during this window.
⚠ Do not drive or operate machinery until all subjective effects and any residual dizziness have fully resolved, typically several hours after last dose.
Safety[edit]
- Acute toxicity
- Low
- Chronic toxicity
- Moderate
- Withdrawal
- Moderate
- Tolerance buildup
- moderate
- Tolerance reset
- —
- Physical
- Moderate
- Psychological
- Low
- Compulsive redosing
- Low
- Dose escalation
- Moderate
- Cross-tol.
- ethanol
Toxicity
Acute toxicity
Acute toxicity is low — roughly 2.5 times less lethal than ethanol in animal studies,[6][9] and the compound holds FDA GRAS status as a food flavoring agent.[17] Human studies confirm tolerability at doses up to 40 g/day for 5 days and 15 g/day for 14 days;[17] a 28-day trial of a related formulation found no meaningful safety changes.[18]
No published acute overdose case reports specific to 1,3-butanediol exist (as distinct from 1,4-butanediol). No data on respiratory depression potential at high doses in humans are available. No human lethal dose has been determined.safety citation needed
Metabolic effects
The compound lowers blood sugar. This was documented in humans receiving it as a dietary supplement[7] and confirmed in animal studies at higher doses.[6] Dehydration is also a risk at higher doses, and metabolic acidosis was observed only at very high doses in animal models.
Liver effects
Minor structural liver changes appeared in rats at high chronic doses, but no fatty liver or liver damage was observed.[6] Population-level safety data at commercially relevant doses remain limited.[19]
Common adverse effects
The most frequently reported adverse effects across published human studies:
- Gastrointestinal distress (nausea, abdominal cramping) — most common, dose-related[13][11]
- Headache — reported in a minority of participants at higher doses[11]
- Euphoria and dizziness — reported at recreational-range doses[13]
Psychological risks
No published reports of psychological distress, psychosis, or psychiatric destabilization attributable to 1,3-butanediol exist. The psychological risk profile parallels ethanol at comparable intoxication levels: impaired judgment, emotional lability, and disinhibition-related risk-taking.[5] No persistent perceptual disturbances have been reported.
Tolerance & dependence
Chronic use in rats produced physical dependence and a withdrawal — tremor and increased seizure susceptibility — matching the pattern seen with alcohol and sedative-hypnotics.[4] Cross-tolerance with ethanol is bidirectional: 1,3-butanediol suppresses alcohol withdrawal, and alcohol-tolerant animals respond less to 1,3-butanediol.[2]
Human abuse liability has not been formally assessed. Given physical dependence and cross-tolerance demonstrated in animal models, dependence potential in chronic recreational users is plausible but unquantified. No published human withdrawal case reports exist.safety citation needed
Drug interactions
Ethanol
Both compounds compete for the same liver enzyme, potentially slowing 1,3-butanediol's conversion to BHB and extending exposure to the parent compound.[4][2] Cross-tolerance is bidirectional — chronic combined use reduces each compound's effect at the CNS level.[4][2]
Paradoxically, ketone supplementation dampens the subjective effects of alcohol in healthy volunteers and may reduce alcohol craving in those with alcohol use disorder.[14][15]
Other CNS depressants
As a CNS depressant with alcohol-like properties, additive sedation with benzodiazepines, barbiturates, opioids, and GHB/GBL is expected. No 1,3-butanediol-specific interaction studies with any of these substance classes exist.safety citation needed
Blood sugar-lowering agents
1,3-Butanediol lowers blood glucose,[7] so additive low blood sugar risk with insulin, metformin, and other diabetes medications is plausible. No published interaction studies exist.
Contraindications
Diabetes and blood sugar instability: 1,3-Butanediol produces documented blood glucose reduction in humans.[7] This creates additive risk for people with diabetes or those taking glucose-lowering medications.
Concurrent CNS depressant use: Additive sedation risk applies at a class level. No combination studies have been published.safety citation needed
Pregnancy: One rat study showed no adverse fetal effects at high chronic doses,[20] but no human pregnancy data exist. Standard precautionary avoidance applies.
Alcohol use disorder: Enzyme competition and cross-tolerance can create unpredictable responses.[14][15] Those with active alcohol use may not respond predictably to either compound.
Harm Reduction[edit]
Forms & Identification
The critical identification concern is distinguishing 1,3-butanediol from 1,4-butanediol, its positional isomer, which converts to GHB and is controlled in multiple jurisdictions. Both are clear, viscous liquids that are nearly indistinguishable by appearance or taste.
Purchasing from established commercial brands (Avela™, KetoneAid) with labeled (R)-1,3-butanediol content largely eliminates this risk. For non-branded product, verify the CAS number on the certificate of analysis: 107-88-0 for 1,3-BD versus 110-63-4 for 1,4-BD. Standard reagent testing kits do not reliably differentiate the two isomers.
Guidelines
- Start with a low dose and wait at least 90 minutes before redosing — peak BHB levels arrive later than the initial alcohol-like onset
- Split the dose over 30–60 minutes to reduce nausea and shift the experience toward the smoother BHB-mediated phase
- Eat a moderate meal beforehand to reduce gastrointestinal distress
- Stay hydrated throughout the session
- If managing diabetes or taking blood sugar-lowering medications, monitor glucose levels — 1,3-BD lowers blood sugar
- Do not combine with ethanol or other CNS depressants — the interaction is complex and unpredictable
- Keep sessions infrequent — animal studies demonstrate physical dependence with chronic use[4]
Set & Setting
1,3-Butanediol produces alcohol-like intoxication. The same environmental considerations that apply to drinking apply here. Social settings with trusted companions are preferable to solitary use, particularly when exploring dosing for the first time. Avoid situations requiring motor coordination, driving, or complex decision-making.
Food intake substantially modulates the experience. Fasted administration produces faster onset and more intense effects. Eating beforehand smooths the curve and reduces gastrointestinal distress. Stay hydrated throughout — the compound can contribute to dehydration at higher doses.
Aftercare & integration. 1,3-Butanediol's shorter duration means the recovery window is compressed compared to alcohol. Most users return to baseline within a few hours. Prioritize hydration and a balanced meal afterward to replenish glucose and fluids.
If gastrointestinal discomfort persists beyond a few hours, rest and bland food are sufficient for most cases. Headache typically resolves with hydration and standard over-the-counter analgesics. Note dose and protocol responses for future reference — individual variability is significant, and females may experience stronger and longer-lasting effects than males.[11]
Recovery & Support
Animal studies demonstrate that chronic 1,3-BD use produces physical dependence with a withdrawal resembling alcohol withdrawal.[4] Bidirectional cross-tolerance with ethanol is established,[2] meaning individuals with a history of alcohol dependence may be at heightened risk.
If regular use has developed and stopping produces anxiety, tremor, or sleep disruption, seek medical guidance — sedative-hypnotic withdrawal can be medically serious. Addiction support resources designed for alcohol dependence are the closest available framework. SAMHSA's National Helpline (1-800-662-4357) provides free, confidential treatment referrals.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
As a CNS depressant, the primary emergency concerns are excessive sedation and possible low blood sugar.
Recognizing an emergency:
- Unresponsiveness or inability to be roused
- Severely slurred speech or loss of motor control beyond typical mild intoxication
- Vomiting while semi-conscious (aspiration risk)
- Signs of low blood sugar: confusion, shakiness, sweating, rapid heartbeat
- Breathing that becomes slow or irregular
Immediate steps:
- Do not leave the person alone
- If conscious and showing signs of low blood sugar, provide a sugary drink or food
- If unconscious, place in the recovery position (on their side) to protect the airway
- Call emergency services if the person cannot be roused, is vomiting while unconscious, or shows breathing changes
- Do not induce vomiting
What to tell the dispatcher: Name the substance (1,3-butanediol), approximate amount consumed, time of ingestion, and current symptoms. Good Samaritan laws in many jurisdictions protect people who call for help during a drug-related emergency.
Legal Status[edit]
As of April 2026, 1,3-butanediol is not a controlled substance in any jurisdiction for which published scheduling data were identified.[17] Its positional isomer 1,4-butanediol — which converts to GHB — is scheduled in several jurisdictions; 1,3-BD has not been affected by these scheduling actions.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United States | Not scheduled (GRAS food ingredient) | Not controlled under the CSA; FDA GRAS status for food flavoring; commercially available as supplement and beverage[17] |
| United Kingdom | Not controlled | Not listed in Schedules to the Misuse of Drugs Act 1971; 1,4-BD is controlled but 1,3-BD is not |
| European Union | Not scheduled | No EU-level controlled substance classification; available as food ingredient |
| Canada | Not scheduled | Not listed under the Controlled Drugs and Substances Act (CDSA) |
| Australia | Not scheduled | Not listed in SUSMP; 1,4-BD listed as border-controlled drug from March 2024 but 1,3-BD is unaffected |
Regulatory considerations
The compound's legal status may evolve as recreational products gain wider distribution and regulatory attention increases. Its structural relationship to 1,4-butanediol could attract structural analog act scrutiny in some jurisdictions, though the pharmacological profiles of the two isomers are fundamentally distinct.
references
- [1]
- [2]
- [3] ^abVeech RL (2014) Ketone ester effects on metabolism and transcription — Journal of Lipid Research doi:10.1194/jlr.r046292
- [4]
- [5]
- [6]