- 4mg/2ml, 4mg/1ml and 2mg/1ml ampoules (IV, IM)
- 0,5mg, 1mg and 2mg tablets (PO and sublingual alternatives)

Executive Summary

(November 2022)

Executive Summary

Lorazepam is an intermediate acting benzodiazepine (BDZ) –a GABA receptor enhancer– with CNS depressant effects including sedative, hypnotic, skeletal muscle relaxing and anticonvulsant activity. It can be administered either by intravenous, intramuscular, sublingual or oral routes. Along with midazolam and clonazepam, lorazepam is one of the most frequently indicated BDZ  in the ED. 

Sedation timing with single 2-4mg dose:

Onset (IV): 5-10 minutes*

Peak Effect (IV): 30 minutes

Duration (IV): 2-6 hours
(*shorter to terminate seizures)

Onset (IM) 15 minutes

Peak Effect (IM) 60 minutes

Duration (IM) 6-8 hours



FDA approved, frequently elected as the first-line BDZ (6): 

FDA not approved, frequently elected BDZ (16, 17, 20): 

FDA not approved, sometimes elected amongst other BDZ (3, 8, 17, 24): 



Benzodiazepines (BDZs) are used for a significant variety of conditions in the ED; their different pharmacological properties allow emergency clinicians to have a wide arsenal to treat each particular patient. 


Seizures and Status Epilepticus (SE):

IV lorazepam is superior to other IV BDZs to treat SE. 


Anxiety disorders, acute anxiety states

Benzodiazepines have a dominant role for short-term, acute management of anxiety disorders in the ED (3). Amongst them, lorazepam is a good alternative between other BDZ for the management of anxiety disorders in the ED, considering its rapid onset of action and long lasting effect. 



Lorazepam is indicated as an adjunctive or single medication to treat undifferentiated agitation in the ED, but midazolam (IM) is considered to be the BDZ of choice to treat severe undifferentiated agitation for its faster onset of action compared with lorazepam (22).


Hyperadrenergic states:

This wide spectrum of conditions can be divided into (i) pathological sympathetic stimulation (eg. thyroid storm, tetanus disease, pain, etc), (ii) exogenous sympathomimetic toxicity and (iii) substance withdrawal response. Caution should be taken as these condition’s syndromic presentations can frequently overlap with undifferentiated agitation, and many of them have serious short-term morbidity and mortality. 

For Alcohol Withdrawal Syndrome lorazepam and diazepam are considered the best alternatives (3), but most authors recommend escalating doses of diazepam as the BDZ of choice (4, 25). 


Caution should be taken with profound sedation, coma and respiratory depression; particularly when repeated doses are administered, or combined with other CNS depressants and/or opioids. 


Benzodiazepines are prone to develop dependence, they should be administered for immediate or short-term therapy in the ED; it is recommended not to prescribe more than a 7-days course of BDZ in this setting (1, 3). Adequate outpatient follow-up should be planned to establish a long-term therapeutic approach to patients who have required BDZs in the ED.

Adult dose

Pediatric dose




Seizures and Status Epilepticus



Sympathomimetic toxicity, alcohol withdrawal

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