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Alcohol and driving

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Even at very low levels alcohol affects our ability to drive, even if we don’t feel any different. Alcohol slows down our central nervous system, affecting:

  • Reaction times
  • Coordination
  • Concentration
  • Judgement
  • Vision

After drinking alcohol, we are more focused on steering and operating the car, and less aware of what is happening around us. We are less likely to see other road users, particularly pedestrians and cyclists.

How much does drinking alcohol increase the risk of being in an accident?

Even one drink can increase your risk of being in a fatal accident.¹ The more you drink, the more your brain functions are affected and the less able you are to drive safely.

There is no safe level of drink driving

Even below the legal limit you are twice as likely to be involved in a collision and 10 of the 11 tasks needed to drive properly are affected.²

What is blood alcohol concentration (BAC)?

Blood alcohol concentration (BAC) is a measurement of the amount of alcohol in our blood. BAC is usually tested using a breath test, but blood tests and urine tests can also be used. The legal limit for drink driving is measured in your breath (22 microgrammes of alcohol per 100 millilitres of breath), blood (50 milligrammes (mg) of alcohol per 100 millilitres of blood) or urine (27 milligrammes of alcohol per 100 millilitres of urine).

BAC is usually tested using a breath test, but blood tests and urine tests can also be used.

The current drink-driving limit is a BAC of 0.05.

For professional, learner and novice drivers the limit is 0.02

Alcohol is involved in 2 in every 5 fatal collisions.³ You don’t just put yourself at risk of injury and death, but also your passengers, other drivers and pedestrians.

Is it safe to drive if I just have 1 or 2 drinks?

No. Any alcohol affects your driving skills. The only safe advice is not to drink if you plan to drive.

I’ve driven lots of times after having a couple of drinks. It hasn’t affected me

Drink-driving without having an accident can make us believe that we can drive safely after having a small amount of alcohol. This is not true. Everyone’s brain function is affected by alcohol. You may not be so lucky the next time.

When is it safe to drive again after drinking alcohol? 

You may have alcohol in your blood for some time after drinking. Alcohol can continue to rise in your blood for up to 3 hours after you stop drinking.

You should allow at least one hour per standard drink for the alcohol to clear from your system. That means after 3 pints, 3 large glasses of wine or 3 double measures of spirits you should wait 6 hours before driving.

1 in 5 fatal road crashes that happen between 6am and 12 noon are alcohol related.4

Can I make the alcohol leave my system faster?

Drinking water or coffee, eating or having a shower will not make the alcohol in your blood disappear any faster – only time can do that.

Prescription medicines and illegal drugs

Drugs – both illegal and legal – can impair your ability to drive. Mixing alcohol with drugs can make their effects even stronger and make driving even more dangerous. If you have taken a recreational drug you should not drive. If you are taking medicine, whether prescribed or purchased over the counter, then read the notes of advice that go with it or check with a pharmacist or doctor. If in doubt, don’t drive.

Read more about alcohol's interactions with medicines and other drugs.

Stay safe

It can seem much easier to hop into the car after drinking. But taking a chance with drink driving can cause consequences that can have a devastating effect on you and other people – injuring or killing yourself or someone else, legal problems, fines, driving bans and criminal charges.

Plan ahead

    • Have a designated driver
    • Find out about public transport options before you go out
    • Budget for a taxi
    • Have a backup plan for getting home – a friend or parent you can call
    • Arrange to be picked up
    • Arrange to stay overnight
    • Do not accept a lift from someone who has been drinking

Walking while drunk can be dangerous – 2 in 3 pedestrians killed in accidents had a BAC above the legal limit.5

For more about driving and alcohol, see the Road Safety Authority – www.rsa.ie

¹ David P Phillips, Ana Luiza R Sousa, Rebecca T Moshfegh. Official blame for drivers with very low blood alcohol content: there is no safe combination of drinking and driving. BMJ, Injury Prevention 21, e1
2 Moskowitz, H., & Robinson, C. D. (1988). Effects of low doses of alcohol on driving-related skills: A review of the evidence. (Report No. DOT HS 807 280) Washington, DC: National Highway Traffic Safety Administration, SRA Technologies, Inc.
3 http://www.rsa.ie/Documents/Press%20Office/Fatal%20Collisions%202008-2012_Alcohol%20as%20a%20Factor.pdf
4 http://www.rsa.ie/Documents/Campaigns/Drink%20Driving%20%E2%80%93%20Fast%20Facts/Dispelling%20the%20Myths%20on%20Drink%20Driving.pdf
5 http://www.rsa.ie/en/RSA/Road-Safety/Campaigns/Current-road-safety-campaigns/Drunken-Pedestrians/

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