Drug driving

The size of the problem and what can be done

Driving under the influence of illicit drugs is a major concern. More than 40 000 people die on European roads each year. Several thousand may be related to illicit drugs.

In Europe, about three million people consume cannabis every day. Research indicates that more than two thirds of drug users drive after having smoked cannabis.

Road side testing, law enforcement, education and treatment helps. The EU needs to agree on common standards in order to save lives where it can.

At least one of every 100 car is driven by someone under the influence of drugs, EMCDDA estimates (European Monitoring Centrel of Drugs and Drug Addiction is a European Commission agency). There are well documented interventions that could reduce the harm, first of all random roadside drug testing.

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The size of the problem

Data from a number of countries indicate that we are faced with a risk that is camparable to driving under the influence of alcohol.

In South Australia between 2003 and 2005, over 23% of drivers or riders killed and tested for the presence of the drugs THC, methylamphetamine and ecstasy, had detectable levels of one or a combination of these drugs (www.sa.gov.au)

Drugs cause more fatal road crashes than speeding and twice as many as alcohol. Data from New South Wales and Victoria (in Australia) shows that 40 per cent of drivers killed at the wheel in Victoria have some form of drug in their system. Half of those had either cannabis, speed or ecstasy in their blood, while the other half were affected by prescription drugs, cocaine or heroin (see report here).

A report published in Ireland in 2004 by researhers at University College Dublin revealed that 72 per cent of drivers suspected of drink driving who were tested in 2000/1 were found to test positive for one or more drugs. 1800 specimens were analysed. Results indicate that 46% of those individuals that had alcohol levels under the legal alcohol limit and 26% over the legal limit contain drugs. (See study on page 51 in this report)

While the overall number of drivers under the influene of alcohol may be larger than for licit and illicit drugs, data suggests that drugs may cause more accidents. A report published in the United Kingdom shows that 15 per cent of all fatal road crashes were alcohol related and as many as 25 per cent were drug related.

One in three drivers suspected of driving while ‘over the limit,’ but subsequently found to be below maximum permissible levels of alcohol, nevertheless tested positive for a range of drugs, reveals research that was published in 2006 in Injury Prevention. Based on the samples in this study from Ireland, the authors calculate that almost 16% (one in six) of all drivers stopped and tested under suspicion of driving under the influence of an ‘intoxicant’ would test positive for drugs (www.physorg.com)

Figures from 2007 in Britain showed that 18 per cent of driver and rider fatalities on our roads have some form of illegal drug in their system. That was higher than the figure for excess alcohol (quoted here). Similar results have been published by reports in Canada where a study concluded that among the adolescent population, driving under the influence of cannabis had become a prevalent activity even surpassing driving under the influence of alcohol. The authors noted that whilst impaired driving has almost exclusively focused on alcohol, at least the same level of attention needed to be paid to driving under the influence of drugs.

Conservative estimates in the USA show that 20% of crashes in the U.S. are caused by drugged driving. This translates into about 8,600 deaths, 580,000 injuries and $33 billion in damages each year (Institute of Behavior and Health). "In a national survey, drugs were present more than 7 times as frequently as alcohol among weekend nighttime drivers with 16 per cent testing positive for drugs, compared to 2 per cent testing at or above the legal limit for alcohol."

The level of harm done is significant. "In a recent study of seriously injured drivers at the Maryland Shock Trauma Center [USA], 5l per cent of the sample tested positive for illegal drugs, compared to 31% who tested positive for alcohol".

A survey by National Highway Traffic Safety Administration (NHTSA) in the USA in 2007 found 16.3 percent of nighttime weekend drivers were drug positive. The survey focused on weekend nighttime drivers and found that the drugs used most commonly by drivers were: marijuana (8.6 percent); cocaine (3.9 percent); and over-the-counter and prescription drugs (3.9 percent). A Dutch study  found traces of cannabis in nearly 5% of the motorists (Mathijssen & Houwing (2005)) making cannabis the most frequent drug found "on the road".

According to a fact sheet of the Dutch Institute for Road Safety Research the problem of drugged driving seems to be increasing. "In the mid 1980s a study in Rotterdam hospitals showed that 5% of the injured drivers had used drugs (Vis, 1989). In a recent study in the town of Tilburg nearly 20% were found to be positive (Mathijssen & Houwing, 2005).

More than a total of 40 000 people die on European roads each year. If one looks at the data and estimates from individual countries it is plausible that 10.000, 25 per cent, of these could be related to illicit drug use.

The risk

Illegal drugs can affect your driving ability by causing impaired coordination, muscle weakness, impaired reaction time, poor vision, an inability to judge distance and speed, and distortions of time, place and space.

Speed, ice or crystal meth (methylamphetamines) increase risk taking and aggression

MDMA can cause acute changes in cognitive performance and impair the brain’s information processing, which in turn can impair driving ability. Basic vehicle control is affected and may result in people taking more risks while driving

The EMCDDA reports in 2008 that about 1% to 2% of drivers during roadside surveys tests positive for drugs in saliva. That is a large number. It will imply that there are hundreds of thousens of drivers on any given day in Europe that are influence by drugs.

Cannabis 'doubles' fatal crash risk

Driving after taking even small amounts of cannabis almost doubles risk of a fatal road accident, a major research study from France suggests. The study was published in British Medical Journal and was based on 10,748 drivers involved in fatal crashes between 2001 and 2003.

The French National Institute for Transport and Safety Research found evidence of cannabis use among 7% of drivers involved in fatal crashes, BBC repports. While even small amounts of cannabis could double the chance of a driver suffering an accident, larger doses could more than triple the risk.

The active component in cannabis is called THC and it impairs mental function and reduces attention and concentration on the driving task. THC significantly increases crash risk even when there are no extreme outward signs of impairment.

Recently a review by Oxford scientists about the impact of cannabis on pilots in flying simulators showed that all studies found that with cannabis pilots' performance deteriorated. "The evidence is that pilots used to smoking cannabis and trained in simulator tasks have impaired function up to 24 hours after smoking cannabis", Bandolier reports (Bandolier is an independent journal about evidence-based healthcare, written by Oxford scientists).

An EU agenda

The European Union has a strong and growing interest in road safety. One of the important risk factors is alcohol, drugs and prescription medicine. 27 November 2003 the Council of Ministers approved a Resolution on combating the impact of psychoactive substances use on road accidents (2004/C 97/01). The resolution is available in several languages of the EU here.

The EU Council of Ministers "underlines the importance of taking any appropriate measures, which may include sanctions, in respect of vehicle drivers who are under the influence of psychoactive substances, which reduce their capacity to drive", and "to ensure issues related to driving under the influence of psychoactive substances are tackled in the context of EU activities in the field of road accidents".

A specific research project is funded under the EU research programme, called DRUID (Driving under the Influence of Drugs, Alcohol and Medicines). One aim of the project is to fill the gaps of knowledge and provide a solid base to generate harmonised, EU-wide regulations for driving under the influence of alcohol, drugs and medicine.

The European Commission agency European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) has a dedicated thematic web resource here.

Things to do: testing and comparable data

While alcohol is alcohol, with particular impairing effects on driving, illicit drugs and prescription drugs have a wide varitey of different effects on the driver. The risk related to drug driving will therefore vary a lot. Not least it will in many cases be difficult for law enforcement officers to identiy a drug driver by visual observation.

That is why random drug testing must be a priority. Random alcohol testing has proven to be a success in reducting accidents. Random testing will have an additional effect on overall consumption of drugs, as it has had on alcohol in some instances. Drunk driving legislation and its enforcement is widely cited as having contributed to the reduction in alcohol consumption in France and elsewhere in Europe.

Testing technology has developed greatly over the last years and in particular the saliva test is now regarded as reliable and effective when used on roadside tests. See European Traffic Police Network (TISPOL) evaluation of oral fluid screening devices (part of the EU funded DRUID research project) and a report from a DRUID workshop of experts reviewing devices and its use.

In addition to stepping up random testing, There should be routine drugs testing of all drivers who are suspected of being over the limit for alcohol since these drivers may often instead be under the influence of drugs.

Another large problem is the lack of data on the size and nature of the problem. Only about half of the EU member states collect data for drivers under the influence of drugs (EMCDDA).

In addition, and perhaps as a result of the lack of data, the focus on drug driving has been lacking too. Drug driving should be moved up on the agenda of road safety, drug policy and prevention.


  • Random roadside drug testing must be applied at the same level as it is for alcohol.  

  • Drivers involved in accidents involing serious injuries and fatalities, should be tested.

  • Drivers testing positive for driving under the influene of alcohol should be testet for drug use.

  • Drivers should be testet on suspicion.  

  • Driver education programs must focus on drug driving the way it now focuses on drink driving.

  • There should be specific drug driving legislation introduced in all countries as well as on EU level.

  • Drivers found guilty of driving under the influence of illegal drugs should be screened for their need for treatment.

  • Drivers found guilty of drug driving should be subject to rehabilitation programmes that includes drug testing as condition for regaining their drivers licences.

Links and resources

European Transport Safety Council, ETSC, Europe

Action Campaign for Education Against Road Tragedies (A-Ceart), Ireland

European Monitoring Centre for Drugs and Drug Addiction, Europe

European Traffic Police Network, Europe

European Commission (Road safety)