Impact of alcohol and drugs when driving

Alcohol and other drugs interfere with this process. They alter the normal function of the brain and body, reducing your ability to make decisions and respond effectively. Even highly skilled and experienced drivers can become dangerous when under the influence of substances.

While different drugs have different effects, any substance that slows you down, speeds you up, or alters your perception can impair your driving, often with tragic consequences.

According to European Commission estimates, around 25% of all road deaths in the EU are alcohol-related. Drink-driving is one of the three main causes of fatal crashes, alongside speeding and failure to wear seatbelts.

Research suggests that 6,500 deaths could be prevented each year in Europe if every driver followed drink-driving laws.

Alcohol affects driving in several ways:

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  It reduces alertness and slows reaction times.
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  It impairs coordination, making basic driving tasks more difficult.
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  It blurs or doubles vision and distorts depth perception, making it hard to judge distance.
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  It affects judgment, often leading to overconfidence and risky behaviour.

As a result, people who drive after drinking are more likely to weave across lanes, speed, miss road signs, and cause collisions.

When you drink, alcohol is absorbed into your bloodstream through the stomach and small intestine.

Blood alcohol content (BAC) is the measurement of how much alcohol is in your blood. Police can measure it with a breathalyser or a blood test.

Because people react differently to alcohol, it’s almost impossible to judge your own BAC accurately. You may feel fine but still be impaired.

The legal BAC limit varies between countries. If you plan to travel internationally, especially by car, make sure you check local regulations in advance. Some countries even have zero tolerance for alcohol behind the wheel.

No. There is no quick way to sober up.

Once alcohol enters your bloodstream, only time will lower your BAC.

On average, the body processes and eliminates about two-thirds of the alcohol in one standard drink per hour. The more you drink, the longer you’ll need to wait before you’re safe to drive.

Drinking coffee or other caffeinated drinks might make you feel more alert, but your driving ability will still be impaired. The only safe option is to wait or find an alternative way home.

Alcohol is a depressant, meaning it slows brain activity. Some prescription drugs, like sedatives, strong painkillers, and certain anxiety medications, have a similar effect.

Even over-the-counter medicines such as cough syrup, cold remedies, and some antihistamines can cause drowsiness or slow reaction times.

When alcohol is combined with another depressant drug, the effects are much stronger and more dangerous. Always check with your doctor or pharmacist before driving if you’re taking prescription or over-the-counter medication.

Stimulants, such as caffeine, amphetamines, and cocaine, increase alertness but do not improve driving skills.

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  A tired driver who uses coffee to stay awake may feel temporarily alert, but when the stimulant effect wears off, fatigue can return suddenly. The only true remedy for tiredness is to stop and rest.
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  Medical doses of amphetamines may not directly impair driving, but they can make some drivers overconfident, leading to risky behaviour.
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  High doses of amphetamines can increase aggression and hostility behind the wheel.

This false sense of confidence combined with distorted perception can be extremely dangerous.

Cannabis affects:

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  Depth perception
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  Concentration and attention span
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  Reaction time
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  Muscle coordination and hand steadiness

These effects make it much harder to drive safely.

Hallucinogens such as LSD, ecstasy, mescaline, and psilocybin can drastically distort perception and mood, making driving under their influence extremely dangerous and unpredictable.

Police can test for drug use in two main ways:

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  Saliva test – a quick, initial check to detect recent drug use.
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  Psychomotor test – assessing coordination, focus, and speech for signs of impairment.

If a saliva test is positive, you may be required to provide a blood sample. Blood test results can take up to two weeks to confirm.

In many countries, zero tolerance laws apply to driving under the influence of drugs or a combination of drugs and alcohol.

Driving under the influence of alcohol or drugs is never worth the risk.

It endangers you, your passengers, and everyone else on the road.

The best way to protect yourself and others is simple:

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  Plan ahead.
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  Know your limits and local laws.
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  Never drive if you’ve been drinking or using drugs.

Have a safe and responsible trip.