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Benzodiazepine Pregnancy: Should not be used during pregnancy, especially during the first and last trimesters, unless in the judgement of the physician such administration is clinically justifiable; benzodiazepines may cause foetal damage. Use in the late phase of pregnancy may require ventilation of the infant at birth and can cause neonatal hypothermia, hypotonia and moderate respiratory depression; neonatal withdrawal has been reported. There are insufficient data on obstetric safety of parenteral lorazepam, including use in caesarean section, so such use is not recommended. Should not be given to breast-feeding mothers unless the expected benefit outweighs the potential risk to the infant.

Lorazepam

Brand names: Ativan

Used in: Delirium & Cognitive Impairment Seizures & Epilepsy

Lorazepam is a benzodiazepine used for severe anxiety, sedation/premedication, and as a first-line treatment for prolonged or repeated seizures and status epilepticus.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: STATUS EPILEPTICUS (adults): 4 mg intravenously. ACUTE ANXIETY (adults): 0.025-0.03 mg/kg (1.75-2.1 mg for an average 70 kg man). PREMEDICATION (adults): 0.05 mg/kg (3.5 mg for an average 70 kg man).
Route: Intravenous or intramuscular injection; the intravenous route is to be preferred. Must always be diluted with an equal volume of compatible diluent for IV administration (may be diluted for IM). Avoid injection into small veins and avoid intra-arterial injection.
Frequency: Status epilepticus: single 4 mg intravenous dose as stated in the SPC (rapid injection is required in status epilepticus). Acute anxiety: repeat 6-hourly. Premedication: IV 30-45 minutes before surgery, or IM 1-1.5 hours before surgery.
SOURCE SCOPE: UK SPC for 'Lorazepam Macure 4 mg/ml solution for injection' - a PARENTERAL product. Oral lorazepam regimens are not covered by this label. No maximum dose is stated in the retrieved posology, so no maxDose is given here. Dosage and duration of therapy should be individualised; the lowest effective dose should be prescribed for the shortest time possible, and treatment withdrawn gradually to minimise withdrawal symptoms. Not to be used for long-term chronic treatment. ELDERLY: may respond to lower doses and half the normal adult dose may be sufficient; for elderly and debilitated patients reduce the initial dose by approximately 50% and adjust as needed and tolerated. RENAL/HEPATIC IMPAIRMENT: lower doses may be sufficient; severe hepatic insufficiency is a contraindication. PAEDIATRIC (verbatim, not a per-kg dose): for premedication and for acute anxiety, 'Lorazepam Macure 4 mg/ml solution for injection is not recommended in children under 12'; for status epilepticus the SPC states 'Paediatric population: 2 mg intravenously'. Verify all paediatric use against a children's formulary. ADMINISTRATION SAFETY: intravenous injection should be given slowly EXCEPT in the control of status epilepticus where rapid injection is required; patients should remain under observation for at least eight hours and preferably overnight; equipment to maintain a patent airway and support ventilation must be available (potentially fatal respiratory depression can occur). US LABELLING (cross-check only, different product - oral tablets): usual range 2-6 mg/day in divided doses, largest dose at bedtime, daily dosage may vary from 1 to 10 mg/day; elderly or debilitated patients initial 1-2 mg/day in divided doses.

Dose adjustments

Renal

Lower doses may be sufficient in patients with renal or hepatic impairment.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

DOSAGE AND ADMINISTRATION Lorazepam tablets are administered orally. For optimal results, dose, frequency of administration, and duration of therapy should be individualized according to patient response. To facilitate this, 0.5 mg, 1 mg, and 2 mg tablets are available. The usual range is 2 to 6 mg/day given in divided doses, the largest dose being taken before bedtime, but the daily dosage may vary from 1 to 10 mg/day. For anxiety, most patients require an initial dose of 2 to 3 mg/day given two times a day or three times a day. For insomnia due to anxiety or transient situational stress, a single daily dose of 2 to 4 mg may be given, usually at bedtime. For elderly or debilitated …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-07-24. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Contraindications

  • Hypersensitivity to the active substance, to benzodiazepines or to any of the excipients
  • Acute pulmonary insufficiency
  • Sleep apnoea syndrome
  • Myasthenia gravis
  • Severe hepatic insufficiency
  • Not recommended for out-patient use unless the patient is accompanied
  • Acute narrow-angle glaucoma (US labelling only; not listed in the UK SPC section 4.3)

Side effects

  • Very common: sedation, drowsiness
  • Common: ataxia, dizziness, confusion
  • Respiratory depression (dose-dependent), apnoea, worsening of sleep apnoea and of obstructive pulmonary disease
  • Hypotension / lowering of blood pressure
  • Paradoxical reactions including anxiety, agitation, excitation, hostility, aggression, rage, sleep disturbance and hallucinations (more likely in children and the elderly); transient anterograde amnesia or memory impairment
  • Uncommon/not known: hypersensitivity and anaphylactic/anaphylactoid reactions, angioedema, thrombocytopenia, agranulocytosis, pancytopenia, SIADH and hyponatraemia, jaundice and raised liver enzymes

Interactions

  • Opioids: concomitant use increases the risk of respiratory depression - limit dosage and duration of concomitant use and monitor closely for respiratory depression and sedation (US labelling; UK SPC section 4.5 was not retrieved)
  • Other CNS depressants (alcohol, barbiturates, antipsychotics, sedative/hypnotics, anxiolytics, antidepressants, narcotic analgesics, sedative antihistamines, anticonvulsants, anaesthetics): increased CNS-depressant effects (US labelling)
  • Clozapine: concomitant use may produce marked sedation, excessive salivation, hypotension, ataxia, delirium and respiratory arrest (US labelling)
  • Valproate: increased lorazepam plasma concentrations and reduced clearance - lorazepam dosage should be reduced to approximately 50% when coadministered (US labelling)
  • Probenecid: may result in a more rapid onset or prolonged effect of lorazepam (US labelling)

Clinical monograph

How it works

It enhances the inhibitory action of GABA at the GABA-A receptor.

Prescribing in practice

  • Respiratory depression and sedation occur, particularly with other CNS depressants — have flumazenil and airway support available where appropriate.
  • Dependence and tolerance develop — use the lowest dose for the shortest time and taper to stop.
  • Use caution in the elderly and in respiratory disease.

Monitoring

Monitor sedation and respiratory status acutely; review the need to continue.

Counselling the patient

  • It causes drowsiness — do not drive or operate machinery, and avoid alcohol.
  • It is for short-term use; do not stop suddenly after regular use.

Evidence & guidelines

A first-line benzodiazepine for status epilepticus (intravenous) and used for severe anxiety/sedation, with dependence and respiratory cautions.

Reference: NICE CG137 Epilepsies; CONVULSE Trial; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

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Featured in these MRCEM clinical pathways

Lorazepam is a core drug in the following exam-focused workups on our sister siteReviseMRCEM.

MRCEM Primary / Intermediate / OSCE candidates: each pathway includes exam-style questions, RCEM/NICE citations, and FAQ summaries.