Alcohol, drugs and driving

Driving under the influence of alcohol and drugs endangers lives.

Road crash statistics show that driving under the influence of drugs and alcohol remains a major factor in the number of people killed and injured on our roads, with around 19% of drivers and motorcycle riders killed on Victoria’s roads having a BAC over 0.05.* In this section, we explore the risks and dangers of driving under the influence, Blood Alcohol Concentration levels, roadside testing and things you should know about prescription medication.

A variety of different types of cocktails

What is a standard drink?

Any alcoholic drink which contains 10 grams of alcohol is called a standard drink. As the alcohol content of drinks varies greatly, it takes differing amounts of different types of alcohol to make up a standard drink.

The biggest problem with keeping drinks standard and within the Blood Alcohol Concentration (BAC) limit is that drinks can be served in larger glasses - and with more alcohol - than standard drinks. The following standard drinks have approximately 8-10 grams of alcohol:

  • 30ml of spirits (40% alc/vol)
  • 60ml of fortified wine (18% alc/vol)
  • 100ml of champagne (12% alc/vol)
  • 100ml of wine (12% alc/vol)
  • 150ml of light wine (8% alc/vol)
  • 280ml of standard strength beer (4.9% alc/vol)
  •  375ml of low-alcohol beer (2.8% alc/vol)

How many drinks does it take to get to 0.05 BAC? 

Your BAC is determined by many factors, including:

  •  what you drink, 
  • how quickly you drink, 
  • how much you have eaten, 
  • how much you weigh,
  • your gender, 
  • the health of your liver, 
  • how fit you are.

Aerated alcoholic drinks like champagne and sparkling wines can also cause your BAC to rise quicker than other drinks with the same alcohol content. As a general rule, to stay under 0.05:

  • Men can have 2 standard drinks in the first hour and 1 drink each following hour.
  • Women can have only 1 standard drink in the first hour and 1 each following hour.

To be safe, if you plan to drink avoid driving altogether and plan a safe way to get home.

How can I work out my BAC?

You can check your BAC by using a coin-operated breath tester on licensed premises, but remember that these machines aren’t guaranteed to be accurate.

In general:

  • a smaller person will have a higher BAC than a larger person,
  • a person with more body fat will tend to have a higher BAC,
  • women absorb alcohol faster and usually have a higher BAC than men who drink the same amount.

Does drinking coffee or taking a shower help lower BAC?

No, the liver eliminates alcohol from the body at around one standard drink per hour. Once alcohol is in your system, the only way to lower it is to let time pass without drinking more alcohol. Drinking coffee, taking a cold shower, exercising, getting fresh air, or vomiting does not lower BAC.

Your BAC will rise as soon as you start drinking and will peak around 30-60 minutes after you stop drinking. However, alcohol metabolism is a very individual thing, and your BAC may continue to rise for up to two hours after your last drink.

Why is drink-driving dangerous?

Road crash statistics show alcohol is still a major factor in the number of people killed and injured on our roads. At 0.05 BAC your risk of crashing is twice as high as a sober driver. The risk of crashing increases dramatically as your BAC level increases.

Alcohol significantly impairs vision, reaction times and co-ordination which are all important to to drive safely.

How do I avoid the risk of drink driving?

If you are planning to drive, the only way to be certain of staying under .05 is to not drink. If you do decide to drink, reduce your risk by:

  • arranging a designated driver, 
  • taking alternative transport like a taxi or public transport, 
  • keeping track of your drinks and how long you have been drinking for, 
  • drinking slowly, alternating between alcoholic and non-alcoholic drinks, 
  • having something to eat while you're drinking, 
  • drinking light rather than full-strength beer, 
  • being careful when drinking mixed spirits or cocktails as you can’t be sure how much alcohol is in them, 
  • using a coin-operated breath tester for a rough guide to your BAC, 
  • waiting at least one hour for each standard drink consumed.

What are the penalties for drink-driving?

The law and penalties for drink driving can be found on the VicRoads website.

The chances of being caught drink driving are higher in Victoria than almost anywhere in the world. According to TAC statistics  1 in 5 drivers and riders who lost their lives in the past five years had a BAC of over 0.05.  

Remember, it’s illegal to drink alcohol while driving or supervising a learner driver.

Driving under the influence of drugs is a major road safety problem because illicit drugs affect your ability to drive safely. Random roadside testing for illicit drugs occurs in Victoria to combat drug driving. In the last five years approximately 41% of all drivers and motorcyclists killed who were tested had drugs in their system, with cannabis and stimulants the most common substances detected.

How drugs are detected

Police test drivers for THC (the active component in cannabis), MDMA, which is known as ecstasy, and methamphetamines (also known as speed, ice or crystal meth).

Roadside saliva testing is not designed to detect the presence of prescribed drugs or common over-the-counter medicines.

How roadside saliva drug tests are conducted:

Drivers are stopped at random on the roadside for a saliva drug test, similar to an alcohol breath test.

  1. Drivers first complete an alcohol breath test and then a saliva drug test. This involves wiping the saliva device on your tongue. The test takes around five minutes to give a reading. If the test is negative, the driver is free to go.
  2. Drivers with a positive reading on the roadside saliva test do a different saliva test in the police drug bus. If the second test also returns a positive reading, the driver will be interviewed by police and part of the second sample will be sent for laboratory analysis. The driver is given the remaining portion of the saliva sample.
  3. The driver is then able to leave but can’t drive their vehicle.
  4. The driver will be informed of the outcome of the laboratory analysis within a few weeks of the roadside saliva testing.
  5. If the driver tests positive for illicit drugs while driving, they will be fined or prosecuted.

Penalties for driving under the influence of drugs

 The law and the penalties for drug driving can be found on the VicRoads website.

Some medications affect reaction time and can make you drowsy. If you’re worried your medication affects your driving, you should continue taking your medication, avoid driving and see your doctor as soon as possible.

Tips to ensure your driving isn’t impaired include:

  • Taking your medication as prescribed.
  • Asking your doctor or pharmacist about the possible effects the medication will have on your driving.
  • Asking about the effect any new medication or change in dosage will have when combined with other medications you are taking.
  • Asking whether it is safe to drink alcohol while taking your medication.