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Drugs and Driving Don't Mix

Safe driving requires precise skills, clear judgment, concentration, and being able to react to what happens on the road.

Drugs affect all of these skills, and not just illegal drugs.

Prescription drugs and even over the counter medicines can affect your driving skills if you don't follow instructions or your doctor's advice.

Taking more than one drug or mixing alcohol and drugs and then driving is even more dangerous. But taking drugs of any kind and then driving puts you at greater risk of injuring or killing yourself, your friends or other innocent people.

Alcohol and other drugs affect driving.

When you drive, your hands, eyes and feet control the vehicle, and your brain controls your hands, eyes and feet. To drive safely, you need to be alert, aware and able to make quick decisions in response to a rapidly changing environment.

Alcohol and other drugs alter the normal function of the brain and body, and interfere with even the most skilled and experienced Drivers ability to drive safely. While different drugs can have different effects on driving, any drug that slows you down, speeds you up or changes the way you see things can affect your driving - too often with tragic consequences.

Alcohol and other depressant drugs

Alcohol blunts alertness and reduces motor coordination. People who drive after using alcohol can't react as quickly when they need to. Their vision is affected, and may be blurred or doubled. Alcohol alters depth perception, making it hard to tell whether other vehicles, pedestrians or objects are close or far away. And because alcohol affects judgment, people who drive after drinking may feel overconfident and not recognize that their driving skills are reduced. Their driving is more likely to be careless or reckless - weaving, speeding, driving off the road and, too often, crashing.

Alcohol is a depressant drug, which means it slows down your brain and body. Other depressant drugs, including some prescription drugs such as sedatives and painkillers, affect a person's ability to drive safely, in a way similar to alcohol. Any drug that causes drowsiness, including some cough, cold or allergy medications, can also affect a person's ability to drive safely. When alcohol and another depressant drug are combined, the effect is more intense and dangerous than the effect of either drug on its own. When taking prescription or over-the-counter medications, it is wise to consult with your doctor or pharmacist before driving.



Stimulant drugs, such as caffeine, amphetamines and cocaine, may increase alertness, but this does not mean they improve driving skills. The tired driver who drinks coffee to stay awake on the road should be aware that the stimulant effect can wear off suddenly, and that the only remedy for fatigue is to pull off the road, and sleep. Amphetamines do not seem to affect driving skills when taken at medical doses, but they do make some people over-confident, which can lead to risky driving. Higher doses of amphetamines often make people hostile and aggressive. People who use cocaine are also likely to feel confident about their driving ability. But cocaine use affects vision, causing blurring, glare and hallucinations. "Snow lights" - weak flashes or movements of light in the peripheral field of vision - tend to make drivers swerve toward or away from the lights. People who use cocaine may also hear sounds that aren't there, such as bells ringing, or smell scents that aren't there, such as smoke or gas, which distract them from their driving.

Marijuana and other hallucinogens

Marijuana impairs depth perception, attention span and concentration, slows reaction time, and decreases muscle strength and hand steadiness - all of which can affect a person's ability to drive safely.

The effects of hallucinogenic drugs, such as LSD, ecstasy, mescaline and psilocybin, distort perception and mood. Driving while under the influence of any of these drugs is extremely dangerous.

In recent years, drugs other than alcohol that act on the brain have increasingly been recognized as hazards to road traffic safety. Overall, research indicates that marijuana is the most prevalent illegal drug detected in impaired drivers, fatally injured drivers, and motor vehicle crash victims. Other drugs also implicated include benzodiazepines, cocaine, opiates, and amphetamines.

Teens and Drugged Driving

According to the National Highway Traffic Safety Administration (NHTSA), vehicle accidents are the leading cause of death among young people age 16 to 20. It is generally accepted that because teens are the least experienced drivers as a group, they have a higher risk of being involved in an accident compared with more experienced drivers. When this lack of experience is combined with the use of marijuana or other substances that impact cognitive and motor abilities, the results can be tragic.

Driving Drugged is Hazardous


Drugs act on the brain and can alter perception, cognition, attention, balance, coordination, reaction time, and other faculties required for safe driving. The effects of specific drugs of abuse differ depending on their mechanisms of action, the amount consumed, the history of the user, and other factors.



The main active chemical in marijuana is delta-9-tetrahydrocannabinol; THC for short. THC affects areas of the brain that control the body's movements, balance, coordination, memory, and judgment, as well as sensations. Because these effects are multifaceted, more research is required to understand marijuana's impact on the ability of drivers to react to complex and unpredictable situations. However, we do know that:

In 60 studies, behavioral and cognitive skills related to driving performance were impaired in a dose-dependent fashion with increasing THC blood levels.
Evidence from both real and simulated driving studies indicates that marijuana can negatively affect a Drivers attentiveness, perception of time and speed, and the ability to draw on information obtained from past experiences.
Research shows that impairment increases significantly when marijuana use is combined with alcohol.
Studies have found that many drivers who test positive for alcohol also test positive for THC, making it clear that drinking and drugged driving are often linked behaviors.

Other Drugs

Prescription drugs: Many medications (e.g., benzodiazepines and opiate analgesics) act on systems in the brain that could impair driving ability. In fact, many prescription drugs come with warnings against the operation of machinery-including motor vehicles-for a specified period of time after use. When prescription drugs are taken without medical supervision (i.e., when abused), impaired driving and other harmful reactions can also result.

In short, drugged driving is a dangerous activity that puts us all at risk.

How drugs really affect your driving

If you think drug-taking has little, or even a positive, impact on your driving you could be tragically mistaken. It's important to bear in mind that it can be hard to determine exactly how a drug will affect your driving ability - impairment caused by drugs can vary according to the individual, drug type, dosage, the length of time the drugs stays in your body, or if the drug has been taken with other drugs or alcohol.


Some people think that marijuana is a 'safer substitute' to drinking, but it can cause concentration to wander, which can affect reaction times. It can also cause paranoia, drowsiness, distorted perception and a sense of disorientation - all of which could cause you to lose control at the wheel.

Marijuana is the most commonly traced drug in drivers. Even though the effects fade after a matter of hours, it can be detected in the blood for up to four weeks. In theory, this can compromise the driver if they're tested positive, even if their driving wasn't adversely affected at the time.

Some experts claim that smoking a marijuana joint has roughly a similar level of impairment on driving ability as drinking four pints of beer. Also, reports show that in the majority of fatal accidents where marijuana has been detected in a Drivers body, alcohol has also been detected. Alcohol alone or in combination with marijuana increases impairment, accident rate and accident responsibility (the same can be applied to other drugs, too).


This is a psycho-stimulant that can lead to misjudging driving speed and stopping distances. It can also cause a distorted sense of light and sound and a feeling of overconfidence, which can lead to aggressive and erratic driving. While it can make you feel alert at first, the effects wear off quickly, leading to an increased danger of falling asleep at the wheel.

Drug driving is considered as serious an offence as drink driving, and carries the same penalties.



A stimulant drug with hallucinogenic properties, ecstasy can distort your sense of vision and heighten sense of sound. Your concentration can be affected, while you may become over-confident and more likely to take dangerous risks.

Ketamine, LSD and magic mushrooms

Drugs such as these with hallucinogenic properties can strongly influence the senses, so drivers may react to objects or sounds that aren't there, and place themselves and other road users in danger. Coordination skills are likely to be greatly affected, and you may experience anxiety, blurred vision and a sense of detachment from reality - all of which could be deadly on the road.

Speed (amphetamine)

While amphetamines might give you a sense of heightened alertness and confidence, they can be highly dangerous for drivers as they distort your perceptions and can make you feel anxious, prone to panic attacks and lose coordination.

Prescription medication


Antihistamines (often used in flu and hay fever remedies) and tranquillizers (used to treat anxiety, depression and sleeping disorders) may significantly affect reaction times and cause drowsiness. If the label advises against 'operating heavy machinery', consider it a warning not to get behind the wheel of a vehicle.

Remember, possession of illegal drugs is an offence - you'll be landed with a heavy penalty (including a fine and/or prison sentence) for possession or intent to supply. Also, if you think someone's on drugs, don't let them drive you. Instead, nominate a sober driver or find another way to travel.