Alcohol and drugs

Alcohol is a contributing factor in about one-third of all fatal crashes. The risk of death due to an alcohol-related crash can be 4 times greater in rural and remote areas of Queensland than urban or city areas.

Alcohol limits your ability to drive safely because it:

  • impairs your ability to concentrate
  • slows your reaction times
  • reduces your ability to do more than one thing at a time
  • affects your vision and hearing
  • makes you feel more confident, which could increase your risk taking
  • relaxes you, which increases the likelihood of falling asleep at the wheel
  • makes simple tasks more difficult.

Blood alcohol concentration

Blood alcohol concentration (BAC) is a measurement of the amount of alcohol in the body. BAC is measured in grams of alcohol per 100 millilitres of blood. At a 0.05 BAC, the body contains 0.05 grams (50 milligrams) of alcohol per 100 millilitres of blood.

BAC starts to rise as soon as you start drinking. It reaches its highest concentration around 30–60 minutes after you stop drinking.

Legal blood alcohol concentration

If you hold an open driver licence, you must maintain a BAC limit of less than 0.05 while driving.

However, you must maintain a zero BAC (0.00) if you:

  • hold a learner permit
  • hold a provisional licence and are under the age of 25
  • drive a truck, bus or taxi.

Factors affecting BAC

Alcohol affects each person differently. Your BAC can be affected by:

  • how much alcohol you drink and how regularly
  • how long you drink alcohol for
  • your weight
  • how much food you eat and the length of time since you last ate
  • your fitness level
  • your liver function and health
  • your mood
  • your gender
  • the type of alcoholic drinks you consume.

Understanding a standard drink

Many drivers unknowingly exceed the legal BAC limit because they don’t know how much is in a standard drink.

A ‘standard drink’ is a guide to help people assess the amount of alcohol they can consume (or have consumed) during a period of time.

As the amount of alcohol in a beverage differs for different beverages, the amount that comprises a standard drink also varies, depending on the beverage. For example, 285 millilitres (a pot glass) of full-strength beer and 30 millilitres (1 nip) of spirits both equal approximately 1 standard drink.

Alcohol packaging provides information on equivalent standard drinks. However, the person drinking the alcohol is responsible for knowing how much they’ve had, especially if they intend to drive afterwards.

If you’re unsure, don’t mix drinking and driving.

Wine consumption

Wine glasses come in various sizes, so the number of standard drinks per serve can vary from one venue to the next.

Typically, 100 millilitres of table wine equals 1 standard drink (i.e. 4 cooking tablespoons of wine). If the wine is served responsibly, you should get 100 millilitres of wine in a wine glass.

However, if the wine is served more generously, it may contain 200 or 250 millilitres of wine, which equals 2 or 2.5 standard drinks. (Also, a large wine glass can hold 250 millilitres or more.)

If you drink 2 glasses of wine that are overfilled, you may actually be drinking 4 or 5 standard drinks.

Wine and spirits can also have varying percentages of alcohol content. The same serving of different wines or spirits can have different alcohol percentages.

Drink limit advice

As a guide, limit your drinking to these amounts to stay below 0.05 BAC:

  • for men: no more than 2 standard drinks in the first hour, and no more than 1 every hour after that
  • for women: no more than 1 standard drink in the first hour, and no more than 1 every hour after that.

Note: This is only an estimate to minimise the risk of exceeding the legal BAC limit to drive.

The only thing that reduces your blood alcohol concentration level is time. Coffee, cold showers, vomiting and exercise do not reduce your BAC.

The liver processes the alcohol from 1 standard drink in about 1 hour. If you consume numerous drinks over a longer period, you could be over 0.05 BAC the next morning after drinking alcohol the night before.

However, everyone is different. Some people need to consume less alcohol to stay under the legal BAC limit. The best plan is not to drive at all if you plan to drink.

If you’re unsure, don’t drive

Do not drive if you have any doubt about your BAC. Make alternative arrangements: call a taxi, catch a bus, get a lift with someone who hasn’t been drinking or stay overnight.

Get more information about drink driving and standard drinks from the Queensland Government website.

Illegal drugs

Driving under the influence of illegal drugs is dangerous and an increasing road safety problem. There is a strong association between illegal drug use and crashes.

Drugs can limit your ability to drive safely by:

  • slowing your reaction times
  • dulling your thinking process, making it difficult to concentrate on driving
  • distorting your perception of speed and distance
  • reducing your ability to drive safely and identify hazards
  • stimulating the nervous system, which can lead to
    • reduced attention span
    • overconfidence
    • aggressive and dangerous driving
    • sudden fatigue as the stimulant effects wear off
    • lack of awareness of your impaired driving ability.

Mixing alcohol and drugs

Combining alcohol and drugs can seriously affect your ability to drive safely. Some drugs can make you feel like you’re not intoxicated when you’re actually over the legal BAC limit.

Never drive after taking drugs.

Zero tolerance

In Queensland, there is zero tolerance for drivers with illegal drugs in their system. Police officers have the authority to conduct random roadside drug tests.

Read more about the effects of drugs on the Queensland Government website.