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How does alcohol affect driving?

Alcohol is a depressant drug. It slows down the activity of the central nervous system, including the brain.

Alcohol could affect your driving by causing:

impaired vision
reduced reaction times
reduced concentration and vigilance
feeling more relaxed and drowsy, which may cause a driver to fall asleep at the wheel
difficulty in understanding sensory information
difficulty doing several tasks at once (e.g. keep in the lane and in the right direction, while concentrating on other traffic)
failure to obey road rules
over confidence, which may lead to risk taking.

The hangover effects of alcohol, the next day, can make it hard to concentrate and drive safely, and might cause you to fall asleep while driving.

A person who has been drinking alcohol may think that if they are especially careful, they will be able to drive safely. However, the alcohol may have affected their view and experience of reality. Their actions and responses may be quite different to what is actually needed, but they may be unaware of how much their driving skills have been affected.

Tips for driving safely

If you intend to drive, the safest option is not to drink.

Keep track of how much you drink

If you do decide to drink, keep track of how much you drink, by monitoring the number of standard drinks you consume each hour.

Some people may need to drink less to keep their blood alcohol concentration (BAC) under 0.05 and drive safely. Find out more about BAC.

Limit your drinking

Start with a non-alcoholic drink, and have a non-alcoholic drink (a "spacer") every second or third drink.
Avoid topping up your glass, as it makes it difficult to keep an accurate track of how much you've had.
Drink low-alcohol drinks, and avoid mixed drinks, like cocktails, as it is difficult to tell how much alcohol they contain.
Avoid drinking in shouts or rounds, so you don't feel pressured to keep up with your friends.
Sip drinks, and avoid salty snacks or other food that increase thirst.

Wait for your BAC to drop before driving

It is important to remember that BAC can continue to rise up up to 3 hours after the last drink was consumed.

The only way to remove alcohol from your system is to allow the body time to process it. Showers, coffee or fresh air will not reduce BAC.

On average, the liver breaks down a little less than one standard drink per hour. Before driving, you should wait at least an hour for each standard drink you've had.