Rehab 4 Addiction

Does Cannabis Use Affect Driving?

If you are a confident and experienced driver, the process of driving can feel effortless and even automatic. As a result, it’s easy to forget about the risks that come with operating a motor vehicle and the various tasks that your brain has to process in order to keep you safe.

Using cannabis can have a noticeable and severe impact on your brain and therefore your driving skills, putting you at risk of being involved in a crash.

This is known as impaired driving and in many cases can result in serious injury or even death.

What is impaired driving?

If you are driving a motor vehicle under the influence of alcohol, drugs or any medication that impacts your ability to drive safely, you are driving while impaired.

An injury that affects your mobility or movement can also be a factor in impaired driving, as well as a severe lack of sleep.

Impaired driving is illegal and can cause serious damage, injury or death to yourself and other people.

Driving under the influence of cannabis is classified as impaired driving under the recent 2015 drug driving laws introduced in the UK. [1]

Even a small amount of cannabis can impair your judgement and decision-making skills, increasing the chances of accident and injury.

How does cannabis use affect my driving?

The laws around driving under the influence of cannabis exist for a reason. This substance can impact your cognitive skills and other motor functions, increasing your risk of causing or being involved in a road accident.

Slower reaction time

Cannabis can slow down your reaction time, meaning that it may take you longer than usual to register danger and take action to avoid it.

If you have been using cannabis and the car in front of you suddenly slams on its brakes, your brain may take longer to understand what is happening.

As a result, you may not be able to brake in time and are subsequently more likely to be involved in an accident.

Distorted perception of time and distance

You may have a different perspective or time or distance after using cannabis, and this can significantly impact your driving skills.

Time may seem to move much slower or faster than normal, and you may find it difficult to judge the distance or speed of another car. This can increase the chances of being involved in an accident when entering a roundabout, for example, as you may not be able to accurately determine the safest time to pull out.

Impaired judgement and decision-making skills

Although cannabis can help you to feel relaxed, it can also lead to poor decision-making and judgement as you may not be thinking as clearly as usual.

You may believe that it’s safe to overtake another car, not realising that there is a sharp bend in the road that prevents you from seeing other cars approaching. Your brain and senses may not be as switched on as usual, and this can be extremely dangerous while in control of a vehicle.

Lack of coordination

Your balance and coordination may also be affected by cannabis use, which can in turn impact your driving skills.

When driving it’s important to focus on the road, anticipate any potential hazards and operate the controls with your hands and feet. Cannabis use can prevent you from carrying out these tasks effectively, making you a potential hazard on the road.

Why does cannabis use affect my driving?

You may understand the effect that cannabis has on your driving, but why exactly does this happen?

One of the most extensively studied components of cannabis is tetrahydrocannabinol (THC), a compound that contributes to the sensation of being ‘high’ when using this substance.

As well as producing the relaxing and euphoric feelings commonly associated with cannabis use, THC can also affect the way your brain functions. [2]

There are specific areas of your brain that are responsible for activities such as balance, coordination, memory and judgements. Most of these functions are automatic, meaning that we do them without even thinking about them.

THC can interfere with these areas and reduce the brain’s ability to function correctly, leading to a lack of coordination as well as poor judgement and decision-making skills. You may find it more difficult to balance, suffer from memory loss and react slower to certain situations.

It is crucial that these areas of the brain function correctly when driving, so when they are impacted by cannabis use there is a higher likelihood of being involved in an accident.

Am I more likely to crash if I drive under the influence of cannabis?

It can be difficult to study the effects that cannabis has on driving, as THC can remain in the system for up to 30 days after last use. [2]

However, research has shown that the risk of being involved in a crash increases significantly after using cannabis. In some cases, the risk is more than doubled. [3]

Additionally, studies have found that drivers with high amounts of THC in their blood can be up to 3-7 times more likely to be responsible for a crash than people who had not used cannabis before driving. [3]

The risk becomes even higher when cannabis is combined with alcohol, although it can be difficult to ascertain whether these effects are primarily due to the alcohol or whether cannabis also played a large role. [4]

Regardless, it is clear that cannabis use can significantly increase your chances of being involved in an accident.

Does the amount of cannabis in my system reflect on my driving?

While any amount of cannabis can have an impact on your driving and can increase your chances of being involved in a road accident, these effects are likely to increase along with the amount of cannabis ingested.

Some studies have indicated that the particular strain of cannabis used may also affect driving impairment, with some strains containing a higher potency of THC than others.

Additionally, people who have recently used cannabis will likely be more impacted by its effects than someone who used it two or three days prior and still has THC present in their system.

Is there a legal limit of cannabis use when driving?

As cannabis use is illegal in the UK, laws around driving under the influence of this substance are strict.

There is a zero-tolerance approach to cannabis in regards to driving, with only 2 micrograms per litre of blood permitted. This rules out any potential defence of accidental exposure and gives the police the power to stop and charge anyone suspected of driving under the influence of cannabis. [1]

Cannabis is classified as a Class B illegal substance in the UK, This means that it is illegal to possess, use, supply or produce this drug.

If you are caught with cannabis you can be sentenced to up to five years in prison or an unlimited fine, and if you are found guilty of supplying or manufacturing this substance then this sentence can increase to up to 14 years in prison.

What happens if I am caught driving under the influence of cannabis?

If the police suspect that your driving has been impaired by cannabis, they can stop you and perform a field impairment assessment to test your sobriety. This may include a roadside drug test to check for cannabis in your system.

These results may indicate that you have been impaired by cannabis and are therefore unfit to drive. You will likely be arrested and brought back to a police station, where you will undergo a blood or urine test to confirm the presence of drugs.

Depending on the results of this test, you may be charged with drug driving. [5]

The penalties for driving under the influence of cannabis include an unlimited fine, a ban from driving for a minimum of one year and/or a prison sentence of up to six months.

This charge will also be reflected on your criminal record and your driving licence.

Aside from the above penalties, a drug driving charge can have a significant impact on your long-term future.

If you have a job that requires you to drive, your employer will be made aware of your drug driving charge.

You will also be faced with an increase in car insurance costs, while a criminal record can also make it difficult to travel to certain countries.

How often do people drive under the influence of cannabis?

As cannabis use becomes more prevalent, the amount of people driving under the influence of this substance is steadily increasing.

One report found that one in four drivers tested were found to have levels of THC in their system, and this may be more common on weekend evenings and nights with approximately 13% of drivers at this time driving under the influence of cannabis. [2]

Unfortunately, the prevalence of this substance may be contributing to more accidents, injuries and deaths on the road.

Cannabis is one of the most common substances in the bodies of drivers involved in fatal motor vehicle accidents, second only to alcohol.

The recent drug driving laws introduced across the UK are intended to reduce the rates of driving under the influence of substances such as cannabis, but time will tell whether they are a match for the growing popularity of this drug.

Learn more about cannabis rehab here.








Boris is our editor-in-chief at Rehab 4 Addiction. Boris is an addiction expert with more than 20 years in the field.  His expertise covers a broad of topics relating to addiction, rehab and recovery. Boris is an addiction therapist and assists in the alcohol detox and rehab process. Boris has been featured on a variety of websites, including the BBC, Verywell Mind and Healthline.