Diazepam

Diastat, Apaurin, Mother's Little Helper

Psychoactive Class

Depressant Anxiolytic Sedative Muscle Relaxant Anticonvulsant GABAergic

Chemical Class

Diazepam is a long-acting benzodiazepine¹ first patented in 1959 by Hoffmann-La Roche and launched in 1963.²³ It is widely regarded as the prototypical benzodiazepine against which others in its class are measured.⁴ Prescribed for anxiety disorders, seizures, alcohol withdrawal, muscle spasms, and insomnia,³ it became one of the most frequently prescribed medications in the world, ranking as the best-selling medication in the United States from 1968 to 1982.³

Dosage & Duration

Dosage

Threshold~2.5 mg

Light2.5-5 mg

Moderate5-15 mg

Heavy15+ mg

Bioavailability

>90%

Doses of 5 mg or more can cause significant deterioration in alertness alongside increased sleepiness. In elderly patients the smallest effective amount is recommended, starting at 2-2.5 mg once or twice daily and increasing gradually only as needed and tolerated.

Duration

Onset30-90 minutes

After Effects1-120 hours

Total10-24 hours

Half-life

30-56 hours

Subjective Effects

Effects vary widely by individual, dose, and context.

Physical

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

Motor control loss Respiratory depression Dizziness Seizure suppression

Cognitive

The cognitive effects of diazepam can be broken down into several components which progressively intensify proportional to dosage. The general head space of diazepam is described by many as one of intense sedation and decreased inhibition. It contains a large number of typical depressant cognitive effects. Paradoxical reactions to benzodiazepines such as increased seizures (in epileptics), aggression, increased anxiety, violent behavior, loss of impulse control, irritability and suicidal behavior sometimes occur (although they are rare in the general population, with an incidence rate below 1%). These paradoxical effects occur with greater frequency in recreational abusers, individuals with mental disorders, children, and patients on high-dosage regimes.

Anxiety suppression Disinhibition Thought deceleration Euphoria Amnesia Information processing suppression Compulsive redosing

Forked from Subjective Effect Documentation

by Josie KinsSeptember 2015.

Reagent Testing

Loading reagent data

Expected colorimetric results are being prepared.

Pharmacology

Pharmacodynamics

Diazepam acts primarily as a positive allosteric modulator of GABA-A receptors at the benzodiazepine binding site, enhancing GABA-mediated chloride ion conductance to hyperpolarize neurons¹ and reduce cortical and limbic system excitability. Its effects vary with receptor subunit composition: α1-containing GABA-A receptors mediate sedative and amnestic effects, α2-containing receptors primarily underlie anxiolytic and myorelaxant activity (with contributions from α3 and α5 subunits), and α5-containing receptors additionally modulate spatial and temporal memory. Diazepam also acts as an agonist at the translocator protein and produces muscle relaxation through inhibition of polysynaptic pathways in the spinal cord. Its anticonvulsant properties may also involve voltage-gated sodium channel blockade and inhibition of depolarization-sensitive calcium uptake at micromolar concentrations.

Pharmacokinetics

Diazepam is rapidly and nearly completely absorbed after oral administration, with greater than 90% absorbed from the gastrointestinal tract.⁵ It is highly lipid-soluble, widely distributed throughout the body, readily crosses the blood-brain barrier, and is extensively bound to plasma proteins (96-99%,¹ primarily albumin). Hepatic metabolism occurs through demethylation (primarily CYP2C19 and CYP3A4, with contributions from CYP2C9, CYP2B6, and CYP3A5) and hydroxylation (CYP3A4, CYP2C19), yielding the active metabolites desmethyldiazepam, temazepam, and oxazepam.⁶ These metabolites undergo glucuronide conjugation and are excreted mainly in the urine,⁵ with very little parent drug eliminated unchanged. CYP2C19 is polymorphic, and poor metabolizers show significantly reduced clearance (12 vs 26 mL/min) and roughly double the elimination half-life compared to extensive metabolizers.⁷ The elimination half-life of diazepam is 30 to 56 hours, while the principal metabolite desmethyldiazepam has a longer half-life of 2 to 7 days, contributing to accumulation with repeated dosing.

Interactions

Dangerous

Highest risk

These combinations are considered extremely harmful and should always be avoided. Reactions to these drugs taken in combination are highly unpredictable and have a potential to cause death.

AlcoholGHB/GBLOpioidsTramadol

Unsafe

Avoid

There is considerable risk of physical harm when taking these combinations, they should be avoided where possible.

DiphenhydraminePCP

Caution

Use caution

These combinations are not usually physically harmful, but may produce undesirable effects, such as physical discomfort or overstimulation. Extreme use may cause physical health issues. Synergistic effects may be unpredictable. Care should be taken when choosing to use this combination.

DXMKetamineMXE

TripSit

Tolerance

Full Tolerance

Tolerance to the effects of diazepam develops with regular use. Extensive accumulation of diazepam and its primary active metabolite desmethyldiazepam occurs with chronic administration, contributing to altered drug response over time. Individuals with established benzodiazepine tolerance may require substantially higher doses than benzodiazepine-naive users, with experienced users sometimes consuming amounts that would be dangerous or fatal for those without tolerance.

Cross Tolerance

Benzodiazepines, Other GABAergic depressants

Baseline Reset

A considerable period of abstinence is recommended between uses to allow tolerance to reset, though specific timeframes are not well-established in available sources.

Harm Potential

Addiction & Dependence

Psychological

High

Diazepam has a high risk of misuse and psychological dependence. The FDA requires boxed warnings describing risks of abuse, misuse, and addiction.⁸ Recreational users, particularly those using stimulants, may escalate dosage from 2 to 25 times the therapeutic dose. Between 50 and 64% of rats will self-administer diazepam in experimental settings.

Physical

Extremely High

Physical dependence develops readily with regular use, with approximately one-third of individuals who take benzodiazepines for longer than four weeks becoming dependent. Withdrawal can be life-threatening, particularly after extended use at high doses, and may include seizures, psychosis, tremors, sweating, nausea, and hallucinations.⁸³ Gradual dose reduction under medical supervision is essential; abrupt discontinuation is dangerous.⁸

Toxicity

Central Nervous System

Chronic use may cause cognitive impairment including memory deficits that can persist for six months or longer after discontinuation; it remains unclear whether these effects are permanent in some individuals.⁹

Respiratory

Respiratory depression can occur at high doses or in overdose, and is more serious in patients with sleep apnea or chronic obstructive airway disease; severe cases may progress to respiratory arrest.¹⁰

Psychosis Risk

Psychosis is a rare but documented withdrawal symptom following cessation of chronic use.⁸ Hallucinations and severe psychiatric symptoms may occur during withdrawal.¹⁰ Paradoxical reactions including excitement, agitation, rage, and in extreme cases suicidal tendencies have been reported during use, more commonly in children, the elderly, and those with substance use history.¹¹

Seizure Risk

Seizures are a serious risk during withdrawal from chronic use and can be life-threatening if discontinuation is too rapid.⁸¹⁰ Paradoxically, frequent use in those with epilepsy may increase seizure risk.⁹ Withdrawal-related seizures necessitate medically supervised gradual dose tapering.¹²

History & Culture

Discovery and Development

Diazepam was the second benzodiazepine developed by chemist Leo Sternbach at Hoffmann-La Roche's facility in Nutley, New Jersey, following his earlier creation of chlordiazepoxide (marketed as Librium), which had received approval for medical use in 1960. Sternbach patented diazepam in 1959, and it…

Legality

International

1961 Single Convention: diazepam is not scheduled.

1971 Convention on Psychotropic Substances: Schedule IV.

1988 Convention: diazepam is not listed in precursor Tables I or II.

By Country

United StatesPrescription onlyControlled · Prescription

21 CFR § 1308.14(c)(18); 21 USC § 829(b)⁸³⁸⁴

Current federal regulation lists diazepam as a Schedule IV depressant with DEA controlled-substances code 2765. Under 21 USC § 829(b), a Schedule IV controlled substance that is a prescription drug may not be dispensed without a written or oral prescription conforming to federal prescription requirements. This corrects the packet's ambiguous ‘Approved’/‘Illicit’ wording to prescription_only federal status.

AustraliaPrescription onlySchedule 4

Therapeutic Goods (Poisons Standard—June 2026) Instrument 2026 (F2026L00633)²⁰²¹²²

The Federal Register records the Therapeutic Goods (Poisons Standard—June 2026) Instrument 2026 as in force, made 28 May 2026 and commencing 1 June 2026. Its Schedule 4 is expressly titled ‘Prescription only medicines and prescription animal remedies’; the current federal instrument lists Diazepam in Schedule 4. The TGA independently defines Schedule 4 as Prescription Only Medicine. This is a federal scheduling baseline and does not determine supplementary state or territory controlled-medicines rules.

BrazilPrescription onlyControlled · Prescription

Portaria SVS/MS n.º 344/1998, Anexo I, Lista B1^2627282930

ANVISA's controlled-substances list expressly places DIAZEPAM in Lista B1, the psychotropic-substances list under Portaria SVS/MS n.º 344/1998. ANVISA identifies Lista B1 substances as subject to Notificação de Receita B, the controlled prescription notification. This classification therefore records prescription-only medical supply, not unrestricted availability.

FrancePrescription onlyControlled · Prescription

Arrêté du 22 février 1990 fixant la liste des substances psychotropes; public medicines database^3637383940

The current French psychotropics order expressly lists Diazépam as a psychotropic substance. Official French public medicine records for diazepam products identify their dispensing classification as Liste I and, for the cited 10 mg product, state that prescription is limited to 12 weeks. This classification records prescription-only controlled medical access rather than unrestricted supply.

IndonesiaPrescription⁴⁴

Available as a prescription medication. Marketed both as a standalone product and in combination formulations with other active ingredients such as metamizole sodium.

MexicoPrescription onlyControlled · Prescription

Ley General de Salud, artículos 245 fracción III y 226 fracción III⁴⁸⁴⁹⁵⁰

The current official Cámara de Diputados consolidated Ley General de Salud lists Diazepam in Article 245, fraction III among psychotropic substances. Article 226 places medicines containing fraction III psychotropics in the prescription-controlled dispensing regime; this establishes prescription-only supply for therapeutic Diazepam products. State-level pharmacy controls may add implementation requirements.

NorwayPrescription onlyControlled · Prescription

Forskrift om narkotika (narkotikaforskriften), FOR-2013-02-14-199; Legemiddelsøk product record⁵⁵⁵⁶

The current Norwegian narcotics regulation lists diazepam as P IV. The official Norwegian Medicines Agency Legemiddelsøk record for diazepam products identifies them as prescription-only (Reseptpliktig: Ja) and in prescription group B. This supports prescription-only medical availability under the narcotics-control regime.

SingaporePrescription onlyControlled · Prescription

Poisons Act 1938 and Poisons Rules^61626364

Singapore Statutes Online lists diazepam in the Schedule to the Poisons Act 1938 as part of the benzodiazepine entry. The Poisons Rules require poisons in the Third Schedule to be sold only in accordance with a prescription by a medical practitioner. This supports prescription-only supply under the poisons-control regime; it does not characterize diazepam as a Misuse of Drugs Act scheduled drug.

SwedenPrescription onlyControlled · Prescription

Läkemedelsverkets föreskrifter (LVFS 2011:10) om förteckningar över narkotika^6768697071

The Swedish Medical Products Agency identifies diazepam products as narcotics in förteckning IV under the controlled-substances lists. The Agency's authorised medicine records for Stesolid and diazepam products identify their prescription status as Receptbelagt. This classification records controlled prescription-only access rather than unrestricted supply.

UkrainePrescription onlyControlled · Prescription

Cabinet of Ministers Resolution No. 770 of 6 May 2000; Law of Ukraine No. 60/95-VR on Narcotic Drugs, Psychotropic Substances and Precursors⁷⁵⁷⁶

The current national controlled-substances list under Resolution No. 770 places Діазепам in Table III, List No. 2 as a psychotropic substance. The Law on Narcotic Drugs, Psychotropic Substances and Precursors permits citizens to acquire Table II and III psychotropics only on a doctor’s prescription, supporting prescription-only medical access.

ArgentinaPrescription onlyControlled · Prescription

Law No. 19.303; ANMAT-approved diazepam product material¹⁷¹⁸¹⁹

Law No. 19.303 regulates psychotropics in Lists I–IV and provides in Article 14 that List III and IV psychotropics may be dispensed only on a retained prescription. Official Argentine legal material identifies diazepam in Lista IV, and ANMAT product material labels diazepam for sale under retained prescription. This supports prescription-only access with retained-prescription controls.

AustriaPrescription onlyControlled · Prescription

Psychotropenverordnung, Anlage 1 section 2 and § 10²³²⁴²⁵

The current RIS consolidated Psychotropenverordnung lists Diazepam exactly in Anlage 1 section 2, covering substances and preparations of Annex IV to the UN Convention on Psychotropic Substances. Section 10 restricts prescription and dispensing of medicines containing psychotropic substances to medical, dental, or veterinary science, and prohibits ordering repeat dispensing for benzodiazepine medicines. BASG explains that prescription medicines may be dispensed only on a physician’s prescription and specifically identifies diazepam among substances for which repeats are excluded.

CanadaPrescription onlyControlled · Prescription

Controlled Drugs and Substances Act, Schedule IV; Benzodiazepines and Other Targeted Substances Regulations (SOR/2000-217), Schedule 1^3132333435

The current Controlled Drugs and Substances Act expressly lists diazepam in Schedule IV. The current Benzodiazepines and Other Targeted Substances Regulations separately list Diazepam in Schedule 1 as a targeted substance, and Health Canada’s Drug Product Database identifies authorised diazepam products as TARGETED SUBSTANCES (CDSA IV). This repairs the earlier entry by pairing the statutory Schedule IV classification with the current targeted-substances regulation and authorised-product record supporting prescription-only supply.

GermanyPrescription onlyControlled · Prescription

Betäubungsmittelgesetz, Anlage III; Arzneimittelverschreibungsverordnung, § 1 and Anlage 1⁴¹⁴²⁴³

Diazepam is listed in BtMG Anlage III, with an exception for preparations containing no other Annex I–III substance and up to 10 mg diazepam per divided form. The exception removes the special BtM classification for those preparations; AMVV § 1 requires prescription dispensing for medicines containing Annex 1 substances. The finding records prescription-only availability while retaining the dosage-specific BtM exception.

IrelandPrescription onlySchedule 4 Part 1 controlled drug

Misuse of Drugs Regulations 2017 (S.I. No. 173/2017), Schedule 4 Part 1; Medicinal Products (Prescription and Control of Supply) Regulations 2003 (S.I. No. 540/2003)⁴⁵⁴⁶⁴⁷

The official Irish Statute Book text for the Misuse of Drugs Regulations 2017 identifies Diazepam in Schedule 4 Part 1. That Schedule is expressly subject to regulations 14–18 and related control requirements; regulation 10(2) permits possession of a Part 1 Schedule 4 drug for medical purposes in accordance with a practitioner's directions, while regulations 8–9 limit authorised supply to persons who may lawfully possess it. The official HPRA authorised-medicine record for Diazepam confirms an approved product's legal supply status as a prescription product that may not be renewed (A).

New ZealandPrescription onlyControlled · Prescription

Misuse of Drugs Act 1975, Schedule 3 Part 5; Medsafe authorised-medicine classification^51525354

Fresh official research confirms that diazepam appears in Part 5 of Schedule 3 to the Misuse of Drugs Act 1975. The current Medsafe-hosted Arrow-Diazepam Consumer Medicine Information is explicitly marked ‘Prescription Medicine,’ and Medsafe explains that prescription medicines may be supplied only on a prescription. Together these primary government sources support prescription_only medical access.

PolandPrescription onlyControlled · Prescription

Rozporządzenie Ministra Zdrowia, consolidated text Dz.U. 2024 poz. 1139; official Register of Medicinal Products, Relanium product 5776^57585960

The current consolidated controlled-substance schedule lists DIAZEPAM in psychotropic group IV-P. The official Register of Medicinal Products’ Relanium 5 mg/ml package (product 5776) identifies the active substance as Diazepamum and gives availability category ‘Rp - Lek wydawany na receptę’ (medicine supplied on prescription). These primary sources establish prescription-only therapeutic availability while correcting the earlier incorrect Rpw designation.

SpainPrescription onlyControlled · Prescription

AEMPS CIMA authorised-medicinal-product record; Orden de 30 de mayo de 1984 (Lista IV de sustancias psicotrópicas)⁶⁵⁶⁶

The Spanish Medicines Agency CIMA database records active marketed diazepam products as ‘Medicamento Sujeto A Prescripción Médica. Psicótropos’ and flags receta true. The official BOE psychotropic-list material identifies diazepam in Lista IV. This records the current prescription-only medicinal-product status alongside the controlled-psychotropic designation.

SwitzerlandPrescription onlyControlled · Prescription

Betäubungsmittelverzeichnisverordnung des EDI (BetmVV-EDI), Verzeichnis b; Swissmedic authorised-medicine dispensing classification⁷²⁷³⁷⁴

Fresh official-source review supports the replacement lead. Fedlex search results identify Diazepam in BetmVV-EDI Verzeichnis b. SwissmedicInfo’s current Psychopax diazepam medicine record identifies Abgabekategorie B, the prescription dispensing category. Direct extraction of both sites was technically unavailable, but current official search results identify the exact substance and designation; this entry should be independently refuted before use.

United KingdomPrescription onlyControlled · Prescription

Misuse of Drugs Act 1971, Schedule 2 Part III; Misuse of Drugs Regulations 2001, Schedule 4 Part I; MHRA authorised product record^777879808182

Current legislation lists Diazepam as a Class C drug in Part III of Schedule 2 to the Misuse of Drugs Act 1971 and in Part I of Schedule 4 to the Misuse of Drugs Regulations 2001. The Schedule 3 prescription-form requirements do not apply to this Schedule 4 Part I classification. Current MHRA product records identify authorised diazepam products as POM (Prescription Only Medicine), supporting prescription-only therapeutic supply.

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Diazepam

Diastat, Apaurin, Mother's Little Helper

Psychoactive Class

Depressant Anxiolytic Sedative Muscle Relaxant Anticonvulsant GABAergic

Chemical Class

Benzodiazepine