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The Additive Effects of Alcohol and Benzodiazepines on Driving



To examine the relationship between the combination of alcohol and benzodiazepines and the risk of committing an unsafe driver action.


We used data from the Fatality Analysis Reporting System (1993-2006) on drivers aged 20 or older who were tested for both alcohol and drugs. Using a case-control design, we compared drivers who had at least one unsafe driver action (UDA; e.g., weaving) recorded in relation to the crash (cases) to drivers who did not (controls).


Drivers who tested positive for intermediate- and long-acting benzodiazepines in combination with alcohol had significantly greater odds of a UDA compared to those under the influence of alcohol alone, up to blood alcohol concentrations (BACs) of 0.08 and 0.05 g/100 ml, respectively. The odds of a UDA with short-acting benzodiazepines combined with alcohol were no different than for alcohol alone.


This study demonstrates that the combination of alcohol and benzodiazepines can have detrimental effects on driving beyond those of alcohol alone. By describing these combined effects in terms of BAC equivalencies, this study also allows for the extrapolation of simple, concrete concepts that communicate risk to the average benzodiazepine user.



Examiner la relation entre la combinaison d’alcool et les benzodiazépines et le risque de commettre un action de conducteur dangereux.


Nous avons utilisé les données du Fatality Analysis Reporting System (1993-2006) sur les conducteurs âgés de 20 ans ou plus qui ont été testés pour l’alcool et les drogues. En utilisant un devis cas-témoin, nous avons comparé les conducteurs ayant au moins une action de conduite dangereuse (par exemple, changements de voie fréquent) enregistré par rapport envers les accidents (cas) aux conducteurs qui n’ont pas (contrôles).


Les conducteurs qui ont testés positifs pour les benzodiazépines à durée d’action intermédiaire et à longue durée d’action en combinaison avec l’alcool avaient une probabilité significativement plus élevée de commettre une action de conduite dangereuse par rapport à l’alcool seul, jusqu’à un taux d’alcool de 0,08 et 0,05 g/100mL, respectivement. Les benzodiazépines à effet de courte durée en combinaison avec l’alcool n’étaient pas différents de l’alcool seul.


Cette étude démontre que la combinaison d’alcool et de benzodiazépines peut avoir des effets néfastes sur la conduite au-delà de celles de l’alcool. En décrivant ces effets combinés sur le plan d’un taux d’alcoolémie équivalent, cette étude permet également l’extrapolation de concepts simples qui communiquent les risques aux utilisateurs de benzodiazépines.

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  1. 1.

    Tu K, Mamdani MM, Hux JE, Tu JB. Progressive trends in the prevalence of benzodiazepine prescribing in older people in Ontario, Canada. J Am Geriatr Soc 2001;49:1341–45.

    CAS  Article  Google Scholar 

  2. 2.

    Vanakoski J, Mattila MJ, Seppala T. Driving under light and dark conditions: Effects of alcohol and diazepam in young and older subjects. J Clin Psychopharmacol 2000;56:453–58.

    CAS  Google Scholar 

  3. 3.

    Willumeit HP, Ott H, Neubert W, Hemmerling KG, Schratzer M, Fichte K. Alcohol interaction of lormetazepam, mepindolol sulphate and diazepam measured by performance on the driving simulator. Pharmacopsychiatry 1984;17(2):36–43.

    CAS  Article  Google Scholar 

  4. 4.

    Brookhuis KA, Volkerts ER, O’Hanlon JF. Repeated dose effects of lormetazepam and flurazepam upon driving performance. Eur J Clin Pharmacol 1990;39(1):83–87.

    CAS  Article  Google Scholar 

  5. 5.

    O’ Hanlon JF, Volkerts ER. Hypnotics and actual driving performance. Acta Psychiatr Scand Suppl 1986;332:95–104.

    Article  Google Scholar 

  6. 6.

    van Laar MW, Volkerts E, Verbaten M. Subchronic effects of the GABA-agonist lorazepam and the 5-HT2A/2C antagonist ritanserin on driving performance, slow wave sleep and daytime sleepiness in healthy volunteers. Psychopharmacology 2001;154(2):189–97.

    Article  Google Scholar 

  7. 7.

    Staner L, Ertle S, Boeijinga P, Rinaudo G, Arnal MA, Muzet A, Luthringer R. Next-day residual effects of hypnotics in DSM-IV primary insomnia: A driving simulator study with simultaneous electroencephalogram monitoring. Psychopharmacology 2005;181:790–98.

    CAS  Article  Google Scholar 

  8. 8.

    van Laar MW, Volkerts ER, van Willigenburg AP. Therapeutic effects and effects on actual driving performance of chronically administered buspirone and diazepam in anxious outpatients. J Clin Psychopharmacol 1992;12(2):86–95.

    PubMed  Google Scholar 

  9. 9.

    Berthelon C, Bocca ML, Denise P, Pottier A. Do zopiclone, zolpidem and flu-nitrazepam have residual effects on simulated task of collision anticipation? J Psychopharmacol 2003;17:324–31.

    CAS  Article  Google Scholar 

  10. 10.

    Verster JC, Volkerts ER, Verbaten MN. Effects of alprazolam on driving ability, memory functioning and psychomotor performance: A randomized, placebo-controlled study. Neuropsychopharmacology 2002;27:260–69.

    CAS  Article  Google Scholar 

  11. 11.

    Verster JC, Veldhuijzen DS, Volkerts ER. Residual effects of sleep medication on driving ability. Sleep Med Rev 2004;8:309–25.

    Article  Google Scholar 

  12. 12.

    Dubois S, Bedard M, Weaver B. The impact of benzodiazepines on safe driving. Traffic Inj Prev 2008;9(5):404–13.

    Article  Google Scholar 

  13. 13.

    Barbone F, McMahon AD, Davey PG, Morris AD, Reid IC, McDevitt DG, MacDonald TM. Association of road-traffic accidents with benzodiazepine use. Lancet 1998;352:1331–36.

    CAS  Article  Google Scholar 

  14. 14.

    Neutel CI. Risk of traffic accident injury after a prescription for a benzo-diazepine. Ann Epidemiol 1995;5:239–44.

    CAS  Article  Google Scholar 

  15. 15.

    Drummer OH, Gerostamoulos J, Batziris H, Chu M, Caplehorn JR, Robertson MD, Swann P. The involvement of drugs in drivers of motor vehicles killed in Australian road traffic crashes. Accid Anal Prev 2004;36(2):239–48.

    Article  Google Scholar 

  16. 16.

    Appenzeller BM, Schneider S, Yegles M, Maul A, Wennig R. Drugs and chronic alcohol abuse in drivers. Forensic Sci Int 2005;155(2-3):83–90.

    Article  Google Scholar 

  17. 17.

    Linnoila M, Stapleton JM, Lister R, Moss H, Lane E, Granger A, Eckardt MJ. Effects of single doses of alprazolam and diazepam, alone and in combination with ethanol, on psychomotor and cognitive performance and on autonom-ic nervous system reactivity in healthy volunteers. Eur J Clin Pharmacol 1990;39(1):21–28.

    CAS  Article  Google Scholar 

  18. 18.

    Longo MC, Hunter CE, Lokan RJ, White JM, White MA. The role of alcohol, benzodiazepines and stimulants in road crashes. 2000. Stockholm, Sweden, 15th International Conference on Alcohol, Drugs & Traffic Safety. May 22, 2000.

    Google Scholar 

  19. 19.

    Longo MC, Hunter CE, Lokan RJ, White JM, White MA. The prevalence of alcohol, cannabinoids, benzodiazepines and stimulants amongst injured drivers and their role in driver culpability: Part II: The relationship between drug prevalence and drug concentration, and driver culpability. Accid Anal Prev 2000;32:623–32.

    CAS  Article  Google Scholar 

  20. 20.

    Baldock MRJ, McLean AJ. Older drivers: Crash involvements rates and causes. Adelaide, Australia: Centre for Automotive Safety Research, 2005.

    Google Scholar 

  21. 21.

    Oehlert GW. A note on the delta method. Am Stat 1992;46(1):27–29.

    Google Scholar 

  22. 22.

    Engeland A, Skurtveit S, Morland J. Risk of road traffic accidents associated with the prescription of drugs: A registry-based cohort study. Ann Epidemiol 2007;17:597–602.

    Article  Google Scholar 

  23. 23.

    Oster G, Russell MW, Huse DM, Adams SF, Imbimbo J. Accident- and injury-related health-care utilization among benzodiazepine users and nonusers. J Clin Psychiatry 1987;48(Suppl):17–21.

    PubMed  Google Scholar 

  24. 24.

    Hemmelgarn B, Suissa S, Huang A, Boivin JF, Pinard G. Benzodiazepine use and the risk of motor vehicle crash in the elderly. JAMA 1997;278(1):27–31.

    CAS  Article  Google Scholar 

  25. 25.

    O’ Hanlon JF, Vermeeren A, Uiterwijk MM, van Veggel LM, Swijgman HF. Anxiolytics’ effects on the actual driving performance of patients and healthy volunteers in a standardized test. An integration of three studies. Neuro-psychobiology 1995;31(2):81–88.

    Google Scholar 

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Corresponding author

Correspondence to Hillary G. Maxwell MPH.

Additional information

Acknowledgements: Funding for this research was provided through research grants from AUTO21, Network of Centres of Excellence, the Ontario Neurotrauma Foundation, and the Thunder Bay Foundation. Michel Bédard is a member of CanDRIVE, a team funded by the Canadian Institutes of Health Research, Institute of Aging. Michel Bédard is also a Canada Research Chair in Aging and Health (; he acknowledges the support of both programs.

Conflict of Interest: None to declare.

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Maxwell, H.G., Dubois, S., Weaver, B. et al. The Additive Effects of Alcohol and Benzodiazepines on Driving. Can J Public Health 101, 353–357 (2010).

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Mots clés

  • conduite automobile
  • benzodiazépines
  • interactions de drogues
  • études cas-témoins

Key words

  • Automobile driving
  • benzodiazepines
  • alcohol drinking
  • drug interactions
  • case control studies