Drink driving:
The dangers & how to stay safe

Even small amounts of alcohol can affect your judgement and ability to react quickly. Driving after drinking puts not only your own life at risk, but also the safety of your passengers, other drivers, road users and pedestrians. A legal limit for driving after drinking alcohol exists in many countries, but the truth is, alcohol can start affecting your behaviour well before you reach the legal limit. Regardless of what the law says, the safest choice is always the same: if you’re drinking any alcohol, don’t drive.

About the author
Dru Jaeger is the co-founder of Club Soda, a mindful drinking movement that empowers people to make healthier choices around alcohol. Through the programmes he designs and leads, Dru helps individuals build confidence in both their personal and social lives. He is also the author of How to Be a Mindful Drinker.

In an attempt to keep all road users safe, most countries set legal limits on how much alcohol you can have in your system while driving(1), but remember these are just guidelines, not guarantees. Even if you’re under the limit, your coordination and reaction times can be impaired. Go over the limit and you can expect a hefty fine, suspended license, or even a prison sentence. The best way of reducing your risk of a traffic crash and causing harm to yourself or others is to stay sober if you are driving. If you’ve had something to drink, always choose a safer way of getting home, like public transport or booking a taxi.

As alcohol is absorbed into our bodies, some of it reaches our brain, where it immediately starts to affect how we process information and respond to what's happening around us. (2) The more we drink, the higher our blood alcohol content (BAC) becomes, and the greater the impact on our brain. (3) This results in slower reaction times, reduced coordination, and poorer judgement.

BAC, measured in milligrams of alcohol per litre of blood, is a widely-recognised measure of how much you have had to drink and how impaired your physical and mental abilities may be after drinking. It’s the standard used by authorities to determine whether or not someone is legally fit to drive. But the truth is, alcohol can start affecting your behaviour well before you reach the legal limit.

Most countries around the world have established legal limits for blood alcohol content (BAC) when driving, and they vary depending on location. In some places, any amount of alcohol in your system is considered to be too much, especially for learner or inexperienced drivers. In others, the legal threshold might be as high as 0.08%. Zero-tolerance policies are often applied to people just starting out on the roads to make sure they’re as safe as possible.

The only accurate way to know your BAC is through testing. Law enforcement agencies typically check BAC through roadside breath tests or blood samples. It’s simple: if you’re found to be over the limit, you’re breaking the law. And the consequences can be serious. In some regions, repeat offenders may be required to install an alcohol interlock device in their vehicle, which prevents the engine from starting if alcohol is detected on their breath.

While there is a clear relationship between how much alcohol you drink and your BAC, your actual level depends on a range of personal factors, like size, age, sex, and metabolism. How quickly you’ve been drinking can also influence alcohol levels.