Updated July 2026 · 8 min read

Lorazepam (Ativan): The ICU Nurse's Guide

Part of the ICU Emergencies Hub — browse every related guide in one place.

Lorazepam is the benzodiazepine the ICU reaches for when a seizure won't stop or a patient is spiraling into alcohol withdrawal. It's predictable, has no active metabolites to accumulate, and works across seizures, agitation, and withdrawal — but its diluent hides a toxicity that only shows up when you run a lot of it.

What lorazepam does

Lorazepam enhances GABA, the brain's main inhibitory neurotransmitter, raising the seizure threshold and producing sedation, anxiolysis, and amnesia. Its intermediate duration and lack of active metabolites make its effect predictable — unlike diazepam, whose long-acting metabolites pile up in hepatic or renal impairment. That reliability is why it's a first choice for stopping seizures.

Status epilepticus — the first rung

When a patient is actively seizing, a benzodiazepine is first-line, and IV lorazepam is a standard choice, typically around 4 mg IV that can be repeated once. The most common reason status persists is underdosing this step — giving too little benzodiazepine, too slowly, and jumping to second-line agents before the first-line drug had a fair chance. Give the adequate dose, then follow with a second-line agent (levetiracetam, fosphenytoin, or valproate) to prevent recurrence.

Alcohol withdrawal

Lorazepam is central to managing alcohol withdrawal, especially in patients with liver disease where its lack of active metabolites is an advantage. Modern practice favors symptom-triggered dosing — using a structured scale like CIWA-Ar to give benzodiazepine when the patient's withdrawal severity warrants it, rather than a fixed schedule. This approach uses less total drug and shortens treatment while still preventing seizures and delirium tremens. The nurse's assessment drives the dosing.

Dosing at a glance

The propylene glycol trap

IV lorazepam is formulated with propylene glycol as a solvent. At the doses used for a seizure or routine agitation this is a non-issue. But on high-dose or prolonged continuous infusions — for example refractory status or a heavily sedated ventilated patient — the propylene glycol load can accumulate and cause a high anion gap metabolic acidosis, an elevated osmolar gap, and acute kidney injury. This is easy to miss because the drug itself seems benign.

General benzodiazepine cautions

Like all benzodiazepines, lorazepam causes dose-dependent respiratory depression and hypotension, especially combined with opioids, and contributes to ICU delirium — a reason routine benzodiazepine sedation has fallen out of favor for lighter, non-benzodiazepine strategies. Reversal with flumazenil is possible but hazardous in dependent or seizure-prone patients, so it is rarely appropriate here.

Bottom line

Lorazepam is the dependable benzodiazepine of critical care: first-line for status epilepticus, a backbone of symptom-triggered alcohol withdrawal, and clean in organ dysfunction thanks to its lack of active metabolites. Give an adequate dose when it counts, let your withdrawal assessment drive the dosing, and remember the one trap that only appears at scale — propylene glycol accumulation on big or prolonged infusions. Respect that, and lorazepam is one of the safest high-value drugs on the unit.

This article is general educational information for licensed clinicians and students, not medical advice or a substitute for your institution's protocols, pharmacy guidance, or a provider's orders. Always follow facility policy and verify doses independently.