Alcohol affects your brain in ways that can increase your risk of accidents and injuries. This means alcohol affects your ability to drive safely.
The more alcohol in your blood, the more it affects your driving.
If you plan to drive, do not drink.
Effects of alcohol on your ability to drive
Alcohol is a depressant. It slows down messaging to and from your brain.
Even 1 drink can:
- cause vision problems
- slow down your reaction times
- reduce your concentration
- affect your coordination or your ability to do more than 1 task at a time
- affect your judgement - for example, for safe overtaking
- make you over-confident and more likely to take risks
How alcohol affects your brain while you drink
Legal drink-driving limits
When you drink, the alcohol quickly enters your bloodstream. The level of alcohol in your blood is called your blood alcohol concentration (BAC) or your blood alcohol level.
Most countries have a legal BAC limit for driving (drink-driving limit).
In Ireland, the drink-driving limit is 50mg for most people. This means 50mgs of alcohol per 100mls of blood.
The legal limit is 20mg if you are a learner, novice or heavy goods vehicle (HGV) driver.
How many drinks put you over the limit
Just 1 standard drink can put you over the legal limit, especially if the limit for you is 20mg.
Most people have a blood alcohol level of 20mg to 50mg after 1 standard drink.
It is difficult to know exactly how much alcohol is in your blood after drinking. It can depend on things such as your weight, sex and metabolism (how your body breaks food and drink down into energy).
It is safer not to drink at all.
What is a standard drink
A standard drink has 10g of pure alcohol.
This is usually around a:
- half a pint of beer
- single pub measure of a spirit
- small glass of wine
But some drinks are much stronger than others. Check the label if you are not sure.
Important
Just 1 standard drink can put some people over the legal drink-driving limit
Breath testing
Gardaí carry out roadside breath testing for alcohol levels. A breath test measures the alcohol content in your lungs. This is directly related to your blood alcohol level.
You may be asked to have a blood test after a breath test to check your BAC.
How long to wait to drive after drinking
How quickly alcohol leaves your system can depend on your age, sex, weight, metabolism and how much drink you had.
It usually takes 1 to 2 hours for 1 standard drink to leave your system. But everyone is different - you may need more or less time to process alcohol.
Even after you stop drinking, the alcohol levels in your system can continue to rise for up to 3 hours.
Nothing can speed up your body's absorption of alcohol. For example, eating food or drinking water or coffee will not make the alcohol in your blood disappear any faster. Only time can do that.
Driving, medicines and illegal drugs
Prescription medicine, medicine you can buy without a prescription and illegal drugs can affect your ability to drive. They can also increase the effects of alcohol.
If you are taking medicine, read the information leaflet or ask a pharmacist or GP if it's safe to drive. If in doubt, do not drive.
Take your medicines as your GP or pharmacist tells you. This is important for your overall health.
Find your patient information leaflet online
Mixing alcohol with medicines and drugs
Tips for getting home safely
To help get home safely after a night out:
- do not drink and drive
- do not let your friends drink and drive
- have a designated driver (someone who will not be drinking alcohol)
- plan public transport options before you go out
- keep money for a taxi
- have a backup plan for getting home - someone you can call or stay with overnight
- arrange to be picked up
- do not accept a lift from someone who has been drinking