Driving After Lorazepam: Wait at Least 24 Hours
Patients who take lorazepam 2.5 mg should not drive or operate machinery for 24 hours after administration, as psychomotor impairment and impaired reactive skills remain statistically significant for at least 12 hours. 1
Evidence-Based Waiting Period
The most rigorous experimental evidence demonstrates that:
- Lorazepam causes significantly greater and longer-lasting impairment compared to other benzodiazepines like diazepam or medazepam 1
- Reactive skills and flicker fusion discrimination remain impaired for 12 hours after a single 2.5 mg oral dose 1
- The 24-hour restriction is necessary because residual effects persist beyond the 12-hour measurement period in controlled studies 1
Why Lorazepam Is Particularly Problematic for Driving
Lorazepam has unique pharmacological properties that make it especially hazardous:
- Duration of action: 1-24 hours with prolonged impairment of psychomotor function 2
- Highly deliriogenic with delayed awakening compared to shorter-acting benzodiazepines 2
- Impairs almost all measured driving-related skills more severely than diazepam or medazepam (P < 0.05 to 0.001) 1
Epidemiological Risk Data
Meta-analysis of benzodiazepine use and traffic accidents reveals:
- 60-80% increased risk of traffic accidents with benzodiazepine use (pooled OR 1.59 for case-control studies; incidence rate ratio 1.81 for cohort studies) 3
- 40% increase in accident responsibility when drivers are using benzodiazepines (pooled OR 1.41) 3
- 7.7-fold increase in accident risk when benzodiazepines are combined with alcohol (pooled OR 7.69) 3
Critical Caveats
Age considerations: Younger drivers (<65 years) show higher accident risk with benzodiazepines (pooled OR 2.21) compared to elderly drivers (pooled OR 1.13), though impairment occurs in both groups 3
Dose dependency: The 24-hour restriction applies to the 2.5 mg dose studied; lower doses may have shorter durations of impairment, but no driving should occur until the patient feels completely normal and alert 1
Alcohol interaction: Patients must be explicitly warned that combining lorazepam with any alcohol dramatically increases crash risk and extends the period of impairment 3
Individual variation: Patients with hepatic or renal impairment, elderly patients, and those taking other CNS depressants may experience prolonged effects requiring extended driving restrictions 2
Comparison to Other Benzodiazepines
For context on relative impairment duration:
- Diazepam 10 mg: 5-7 hours restriction 1
- Medazepam 15 mg: 5-7 hours restriction 1
- Lorazepam 2.5 mg: 24 hours restriction 1
This demonstrates that lorazepam's intermediate half-life paradoxically produces more prolonged functional impairment than some longer-acting agents 1