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Lorazepam

Group: Depressants
Nicknames: Ativan
Last reviewed: October 2026

Pharmacology

Like all benzodiazepines, lorazepam works primarily as a gamma-aminobutyric acid type A (GABA-A) receptor positive allosteric modulator. What this means is that lorazepam increases the effects of GABA, our brain’s main inhibitory neurotransmitter which turns down nerve signals, thereby calming the brain and subsequently the mind. Its actions are similar to those of diazepam (Valium) but it is considerably more potent (1 mg lorazepam is equivalent to 10 mg diazepam).

Lorazepam has a high oral bioavailability of around 85%, meaning it is efficiently absorbed when taken by mouth. Following oral administration, lorazepam is slowly absorbed by the body. Peak concentrations in plasma (proportionate to the dose) occur approximately 2 hours after ingestion. Lorazepam has an average duration of approximately 12 hours.

UGT enzymes rapidly convert lorazepam into its inactive metabolite lorazepam-glucuronide, which is then excreted in urine. Differences in the rate of conversion depend on a range of individual factors including weight and cigarette smoking.

When lorazepam is taken long term, the brain’s GABA receptors become desensitised, requiring higher doses for the same effect. It is advised that people taking lorazepam long term do not stop suddenly (cold-turkey). Desensitised GABA receptors take a while to get back to baseline, meaning they will be unable to keep nerve signals in check without lorazepam which may lead to dangerous withdrawal symptoms such as seizures. Instead, it is advised to taper gradually with medical supervision.

As lorazepam turns down brain signals, combining the drug with other depressant drugs increases the risk of overdose. Drinking alcohol alongside lorazepam can cause severe sedation, intoxication and blackouts. In combination with opioids, lorazepam can slow down breathing to dangerous levels.

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