Diazepam
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Anxiety disorders / short-term relief of anxiety symptoms | Adults and children ≥6 months | Monotherapy | FDA Approved |
| Acute alcohol withdrawal (agitation, tremor, delirium tremens, hallucinosis) | Adults | Monotherapy | FDA Approved |
| Skeletal muscle spasm (reflex spasm, upper motor neuron spasticity, athetosis, stiff-person syndrome) | Adults and children ≥6 months | Adjunctive | FDA Approved |
| Convulsive disorders (adjunct) | Adults and children ≥6 months | Adjunctive (not sole therapy) | FDA Approved |
| Acute seizure rescue (rectal gel / nasal spray) | Ages ≥2 years (Diastat); ≥6 years (Valtoco) | Acute intermittent rescue | FDA Approved |
Diazepam is the prototypical benzodiazepine with the broadest range of FDA-approved indications among the class. Its high lipid solubility enables rapid CNS penetration (onset within minutes via IV), but also leads to quick redistribution away from the brain after single doses, limiting anticonvulsant duration to approximately 20–30 minutes following IV administration. This contrasts with lorazepam, which has a longer duration of anticonvulsant action. Diazepam produces multiple pharmacologically active metabolites — notably N-desmethyldiazepam (half-life up to 100 hours), temazepam, and oxazepam — which contribute to its prolonged clinical effects and pronounced accumulation with repeated dosing. Long-term efficacy beyond 4 months has not been established for anxiety.
ICU sedation: Continuous or intermittent IV infusion for mechanically ventilated patients. Evidence quality: Moderate.
Paediatric spasticity (cerebral palsy): Used for short-term spasticity management. Evidence quality: Moderate.
Procedural sedation: IV diazepam for endoscopy, cardioversion, and minor surgical procedures. Evidence quality: High (long clinical experience).
Benzodiazepine-responsive movement disorders: Including stiff-person syndrome variants. Evidence quality: Moderate.
Dosing
Oral Dosing — Adults
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Anxiety — mild | 2 mg BID–TID | 2–5 mg BID–QID | Usual upper: 40 mg/day | Individualise; use lowest effective dose; PI notes some may need higher Efficacy beyond 4 months not established (FDA PI) |
| Anxiety — moderate to severe | 5 mg BID–QID | 5–10 mg BID–QID | Usual upper: 40 mg/day | Depending on severity of symptoms (FDA PI: 2–10 mg, 2–4 times daily) Increase cautiously to avoid adverse effects |
| Acute alcohol withdrawal | 10 mg TID–QID | 5 mg TID–QID as needed | 30–40 mg/day (day 1) | Loading in first 24 hours (10 mg 3–4x), then reduce to 5 mg 3–4x daily Symptom-triggered dosing via CIWA-Ar may be preferred |
| Skeletal muscle spasm | 2 mg TID–QID | 2–10 mg TID–QID | Usual upper: 40 mg/day | Includes reflex spasm, spasticity (cerebral palsy, paraplegia), stiff-person syndrome Long-term use may require tolerance assessment |
| Adjunct in convulsive disorders | 2 mg BID–QID | 2–10 mg BID–QID | Usual upper: 40 mg/day | Not effective as sole therapy; add to existing anticonvulsant Abrupt withdrawal may worsen seizures |
Special Populations — Oral
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Elderly or debilitated patients | 2–2.5 mg once or twice daily | Increase gradually as needed | Lowest effective | t½ increases ~1 hour per year of age from 20 h at age 20 Extensive accumulation of parent drug and metabolites in elderly |
| Paediatric (≥6 months) | 1–2.5 mg TID–QID | Increase gradually as needed | Individualise | Initiate with lowest dose; not for use <6 months Paradoxical reactions more common in children |
Rectal and Nasal — Seizure Rescue
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Seizure rescue — rectal gel (Diastat; ≥2 years) | 0.2–0.5 mg/kg (age-based) | Repeat after 4–12 h if needed | 20 mg/dose; max 2 doses/episode | Round to nearest 2.5 mg increment; ≤5 episodes/month 2–5 yr: 0.5 mg/kg; 6–11 yr: 0.3 mg/kg; ≥12 yr: 0.2 mg/kg |
| Seizure rescue — nasal spray (Valtoco; ≥6 years) | 5, 7.5, or 10 mg (weight-based) | Second dose after ≥4 h if needed | 2 doses/episode; ≤5 episodes/month | One spray per nostril (alternating nostrils for 2-spray doses) Not for daily use; intended for intermittent rescue only |
Diazepam produces three pharmacologically active metabolites: N-desmethyldiazepam (t½ up to 100 hours), temazepam, and oxazepam. With repeated dosing, parent drug and metabolites accumulate substantially — particularly in elderly patients and those with hepatic impairment. An elderly patient who appears well on day 1 may develop progressive sedation, confusion, and ataxia over days to weeks as steady-state concentrations build. This accumulation profile is a key reason clinicians may prefer lorazepam or oxazepam in elderly or hepatically impaired patients, since those agents undergo direct glucuronidation without CYP-dependent metabolism or active metabolite formation.
Pharmacology
Mechanism of Action
Diazepam is the prototypical 1,4-benzodiazepine that facilitates the action of GABA, the major inhibitory neurotransmitter in the CNS. By binding to the benzodiazepine allosteric site on the GABA-A receptor, diazepam increases the frequency of chloride channel opening in the presence of GABA, resulting in neuronal hyperpolarisation. This produces its characteristic spectrum of anxiolytic, sedative, muscle-relaxant, anticonvulsant, and amnestic effects. Diazepam acts on parts of the limbic system, the thalamus, and the hypothalamus. Unlike antipsychotics, it has no demonstrable peripheral autonomic blocking action and does not produce extrapyramidal side effects. Its high lipid solubility enables rapid crossing of the blood-brain barrier, accounting for its fast onset of action, but also causes rapid redistribution to peripheral fat stores after single IV doses, limiting the duration of acute CNS effects.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | >90% absorbed orally; Tmax 1–1.5 h (fasting), ~2.5 h (with food); food decreases Cmax by 20% and AUC by 27% | Rapid oral onset; food delays and reduces peak levels but does not affect clinical significance for most indications |
| Distribution | Vd 0.8–1.0 L/kg (young adults); 98% protein bound; crosses placenta, blood-brain barrier, and enters breast milk (~1/10 maternal plasma levels) | Highly lipophilic; rapid CNS penetration then redistribution to fat; Vd increases with age and hepatic disease; elderly have lower peak but higher trough on chronic dosing |
| Metabolism | N-demethylation via CYP3A4 and CYP2C19 to N-desmethyldiazepam (active, t½ up to 100 h); hydroxylation via CYP3A4 to temazepam (active); both further metabolised to oxazepam (active) and then glucuronidated | Multiple CYP-dependent steps create extensive drug interaction potential; 3 active metabolites cause prolonged clinical effect and accumulation; inhibitors of CYP3A4 or CYP2C19 significantly increase exposure |
| Elimination | t½ up to 48 h (parent); N-desmethyldiazepam t½ up to 100 h; clearance 20–30 mL/min (young adults); excreted mainly in urine as glucuronide conjugates | Elderly: t½ increases ~1 h/year of age; cirrhosis: 2–5x increase in t½ (individual values >500 h reported); children 3–8 yr: mean t½ 18 h; neonates: t½ ~30–54 h |
Side Effects
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Drowsiness | Most common | Dose-dependent; enhanced by active metabolites; may persist longer than expected due to accumulation |
| Fatigue | Very common | Overlaps with drowsiness; may worsen with repeated dosing as metabolites accumulate |
| Muscle Weakness | Very common | Reflection of muscle-relaxant properties; fall risk in elderly and debilitated patients |
| Ataxia | Very common | Dose-related; significant contributor to falls and fractures (post-marketing reports) |
Note: The FDA Valium oral PI lists “most commonly reported” adverse effects without specific incidence percentages from placebo-controlled trials. The above effects are identified as the most frequent based on the PI’s adverse reactions section and extensive clinical experience.
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Confusion | Reported | More common in elderly; may mimic or worsen delirium; enhanced by metabolite accumulation |
| Depression | Reported | Pre-existing depression may emerge; protective measures may be necessary in at-risk patients |
| Dysarthria / Slurred Speech | Reported | Dose-dependent; sign of excessive CNS depression |
| Blurred Vision / Diplopia | Reported | Visual disturbance; may impair driving |
| Dizziness / Vertigo | Reported | Contributes to fall risk |
| Hypotension | Reported | More relevant with IV administration; may be orthostatic |
| Constipation / Nausea | Reported | GI disturbance generally mild |
| Anterograde Amnesia | Reported | Occurs at therapeutic doses; risk increases with dose; may be associated with inappropriate behaviour |
| Changes in Libido / Urinary Retention | Reported | Urogenital effects including incontinence |
| Changes in Salivation | Reported | Both dry mouth and hypersalivation described |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Physical Dependence / Withdrawal (including seizures) | Common with prolonged use | On abrupt discontinuation | Never stop abruptly; gradual taper essential; withdrawal may include tremor, cramps, vomiting, sweating, seizures, psychosis |
| Respiratory Depression | Dose-dependent; higher with IV and opioid co-use | Minutes (IV); hours (oral) | Discontinue; ventilatory support; flumazenil as adjunct (caution in long-term BZD users and epilepsy) |
| Paradoxical Reactions (rage, hallucinations, psychosis, agitation) | Rare | Any time; more common in children and elderly | Discontinue diazepam |
| Falls and Fractures | Post-marketing reports | Ongoing; risk increased with concomitant sedatives and in elderly | Fall risk assessment; consider deprescribing; physiotherapy |
| Neutropenia / Jaundice | Isolated reports | Variable | Periodic blood counts and LFTs on long-term therapy (FDA PI) |
| Neonatal Flaccidity / Respiratory Depression | Expected with late-pregnancy or labour exposure | Birth / neonatal period | Monitor neonate; immature metabolic pathways prolong drug effects in neonates (t½ ~30–54 h) |
Diazepam’s elimination half-life increases approximately 1 hour for every year of age starting from a baseline of ~20 hours at age 20. In a 75-year-old patient, the parent compound half-life may exceed 75 hours, and the active metabolite N-desmethyldiazepam may persist far longer. The AGS Beers Criteria identifies diazepam as a potentially inappropriate medication in older adults. Lorazepam or oxazepam (which are glucuronidated directly without active metabolites) are generally safer alternatives in this population.
Drug Interactions
Diazepam is metabolised via CYP3A4 and CYP2C19, producing active metabolites through multiple oxidative steps before final glucuronidation. This creates a broad drug interaction profile — significantly wider than lorazepam (which bypasses CYP450 entirely) or even alprazolam (CYP3A4 only). Both pharmacokinetic and pharmacodynamic interactions are clinically important.
Monitoring
- Sedation & Psychomotor FunctionEach visit; extra vigilance days 3–14
RoutineActive metabolites accumulate over 5–7 half-lives; peak sedation may not appear until days into therapy. Assess driving safety and cognitive performance. - Abuse / Misuse RiskBaseline, each visit
RoutineStandardised screening before prescribing. Monitor for dose escalation, early refill requests, multiple prescribers. - Mood & SuicidalityEach visit
RoutineSuicidal tendencies may be present in depressed patients; not recommended for psychotic patients; protective measures may be necessary. - CBC & Liver FunctionPeriodically on long-term therapy
RoutineIsolated reports of neutropenia and jaundice. Periodic blood counts and LFTs advisable (FDA PI). Hepatic impairment dramatically prolongs elimination. - Hepatic Function (if impaired)Baseline; ongoing
Trigger-basedCirrhosis increases t½ 2–5 fold (individual t½ >500 h reported). Contraindicated in severe hepatic insufficiency. Hepatic encephalopathy may be precipitated. - Fall Risk (Elderly)Baseline, q3 months
RoutineFalls and fractures reported post-marketing. Risk increased with concomitant sedatives and alcohol. Beers Criteria lists diazepam as potentially inappropriate in older adults. - Respiratory FunctionBaseline; ongoing in COPD/sleep apnoea
Trigger-basedLower doses recommended in chronic respiratory insufficiency. Contraindicated in severe respiratory insufficiency and sleep apnoea syndrome. - Treatment Duration Reviewq3 months
RoutineEfficacy beyond 4 months not established. Tolerance may develop. Document clinical justification for continued use.
Contraindications & Cautions
Absolute Contraindications
- Known hypersensitivity to diazepam
- Paediatric patients <6 months (insufficient clinical experience)
- Myasthenia gravis
- Severe respiratory insufficiency
- Severe hepatic insufficiency
- Sleep apnoea syndrome
- Acute narrow-angle glaucoma (may use in open-angle glaucoma with appropriate therapy)
Relative Contraindications (Specialist Input Recommended)
- Psychotic disorders — not recommended; should not replace appropriate treatment
- Severe depression — suicidal tendencies may be present; protective measures needed
- Active substance use disorder — addiction-prone individuals require careful surveillance
- Pregnancy — teratogenic in mice/hamsters at high doses; neonatal flaccidity, respiratory depression, and withdrawal with late-pregnancy use
Use with Caution
- Elderly patients — extensive accumulation; initial 2–2.5 mg QD–BID; AGS Beers Criteria potentially inappropriate medication
- Mild-moderate hepatic impairment — 2–5 fold t½ increase; reduced clearance
- Renal impairment (elderly) — metabolite accumulation; toxicity risk increased
- Chronic respiratory insufficiency — lower dose recommended; risk of respiratory depression
- History of alcohol or drug abuse — use extreme caution
Combined use of benzodiazepines and opioids may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing for patients with no adequate alternative. Use lowest doses for shortest duration.
Diazepam exposes users to risks of abuse, misuse, and addiction. Assess each patient’s risk before prescribing and throughout treatment.
Continued use may lead to physical dependence. Abrupt discontinuation can precipitate life-threatening withdrawal reactions including seizures. Use gradual taper to discontinue.
Patient Counselling
Purpose of Therapy
Diazepam is prescribed to reduce anxiety, relieve muscle spasm, help manage alcohol withdrawal, or support seizure management. It works by calming overactive nerve signals in the brain. Because diazepam and its breakdown products stay in your body for a long time, effects can build up over several days of use. Regular check-ups with your prescriber are essential.
How to Take
Take diazepam exactly as prescribed. Tablets should be swallowed whole with water. Taking with food will delay the effect but does not change the overall amount absorbed. For seizure rescue (rectal gel or nasal spray), follow the specific instructions provided and ensure a caregiver is trained in administration. Store securely — diazepam is a controlled substance.
Sources
- Valium (diazepam) Tablets. Full Prescribing Information. Genentech USA, Inc. Revised February 2021. FDA LabelPrimary source for all oral dosing, adverse reactions, pharmacokinetic data (including hepatic/geriatric special populations), drug interactions, and contraindications.
- Valium (diazepam) Tablets. Full Prescribing Information. Waylis Therapeutics LLC. Revised 2023. FDA Label (2023)Updated label with current boxed warnings (opioid co-use, abuse/misuse/addiction, dependence/withdrawal).
- Diastat (diazepam rectal gel). Full Prescribing Information. Bausch Health. DailyMedSource for age-based rectal rescue dosing (0.2–0.5 mg/kg) and seizure rescue administration guidelines.
- Treiman DM, Meyers PD, Walton NY, et al. A comparison of four treatments for generalized convulsive status epilepticus. N Engl J Med. 1998;339(12):792-798. DOIVA Cooperative Study comparing IV diazepam to lorazepam, phenobarbital, and phenytoin for SE; lorazepam found superior as first-line.
- Alldredge BK, Gelb AM, Isaacs SM, et al. A comparison of lorazepam, diazepam, and placebo for the treatment of out-of-hospital status epilepticus. N Engl J Med. 2001;345(9):631-637. DOIPrehospital SE trial establishing both lorazepam and diazepam as effective vs placebo; diazepam has shorter anticonvulsant duration.
- Calcaterra NE, Barrow JC. Classics in chemical neuroscience: diazepam (Valium). ACS Chem Neurosci. 2014;5(4):253-260. DOIComprehensive historical and pharmacological review of diazepam covering its development, mechanism, and clinical impact.
- Glauser T, Shinnar S, Gloss D, et al. Evidence-based guideline: treatment of convulsive status epilepticus in children and adults. Epilepsy Curr. 2016;16(1):48-61. DOIAES guideline listing IV diazepam as Level A first-line for SE alongside IV lorazepam and IM midazolam.
- By the 2023 American Geriatrics Society Beers Criteria Update Expert Panel. American Geriatrics Society 2023 updated AGS Beers Criteria. J Am Geriatr Soc. 2023;71(7):2052-2081. DOILists all benzodiazepines, including diazepam, as potentially inappropriate in older adults due to cognitive impairment, delirium, falls, and fracture risk.
- Sachdeva A, Choudhary M, Chandra M. Alcohol withdrawal syndrome: benzodiazepines and beyond. J Clin Diagn Res. 2015;9(9):VE01-VE07. DOIReview supporting diazepam and chlordiazepoxide as first-choice agents for alcohol withdrawal due to their long half-lives providing smoother withdrawal profiles.
- Rudolph U, Knoflach F. Beyond classical benzodiazepines: novel therapeutic potential of GABAA receptor subtypes. Nat Rev Drug Discov. 2011;10(9):685-697. DOIReview of GABA-A receptor subtype pharmacology explaining benzodiazepine anxiolytic, anticonvulsant, muscle-relaxant, and sedative effects.
- Greenblatt DJ, Shader RI, Divoll M, Harmatz JS. Benzodiazepines: a summary of pharmacokinetic properties. Br J Clin Pharmacol. 1981;11(Suppl 1):11S-16S. DOIDefinitive comparative PK review covering diazepam distribution, metabolism, and age-related changes in elimination.
- Sharbaf Shoar N, Bistas KG, Patel P, Saadabadi A. Diazepam. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan–. Updated February 29, 2024. NCBI BookshelfCurrent clinician-oriented review covering all approved indications, off-label uses, dosing across routes, and special populations.