How many drinks does it take to affect your judgment?

Alcohol affects your ability to drive. You are more at risk of being in an accident after you've been drinking.

Even after 1 drink, alcohol affects:

• reaction times
• coordination
• concentration
• judgement
• vision

The more alcohol in your system, the more it affects your ability to drive.

If you plan to drive, it's best not to drink at all.

Legal drink-driving limits

Blood Alcohol Concentration (BAC) is a measurement of the amount of alcohol in our blood.

The current drink-driving limit is a BAC of 0.05. For professional, learner and novice drivers the limit is 0.02.

Most people will have a BAC of 0.02 to 0.05 after one standard drink.

Related topic

What is a standard drink

Gardaí carry out roadside breath testing for alcohol levels. A breath test measures microgrammes of alcohol per 100 millilitres of breath. The legal limit is 22 microgrammes.

Read more about drinking and driving from the Road Safety Authority.

When it's safe to drive again

It takes most people 1 to 2 hours to process one standard drink. That means after 3 standard drinks you should wait at least 3 hours before driving.

After you stop drinking, the alcohol levels in your system can continue to rise for up to 3 hours.

Nothing can speed up the absorption of alcohol by your body. For example, drinking water or coffee, eating or having a shower. These will not make the alcohol in your blood disappear any faster. Only time can do that.

Driving, medicines and illegal drugs

Legal and illegal drugs can affect your ability to drive. They can also increase the effects of alcohol.

If you are taking medication, read the information leaflet or ask a pharmacist or GP if it's safe to drive. If in doubt, don’t drive.

Driving under the influence of any drug is illegal in Ireland. The Gardaí now conduct roadside drug testing.

Related topic

Drug interactions with alcohol

Drug driving laws in Ireland

Safety Tips

To help keep you safe on a night out:

• 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
• don't accept a lift from someone who has been drinking

Use our drinks calculator to find out how your drinking affects your health, money and weight.

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It’s different for each person

How alcohol affects you can depend on a range of factors, including your:

• sex
• mental and physical health
• medical conditions
• use of other drugs and medications.

Alcohol can affect you more quickly if you:

• drink on an empty stomach
• have a lower tolerance to alcohol
• have a lower percentage of muscle on your body
• are a young person
• weigh less
• don’t usually drink alcohol.

What happens in your body

As you drink alcohol, it:

• passes into your blood through the walls of the stomach and small intestine
• travels to all parts of the body including the brain
• slows down your brain and affects almost all parts your body
• affects the way you think, feel and behave.

Alcohol only takes a few minutes to reach the brain in an average, healthy person.

Your liver removes most of the alcohol in your body by breaking it down.

Blood alcohol levels

As you drink, the level of alcohol in your blood rises.

The level of alcohol in your blood is called blood alcohol concentration (BAC). A BAC of 0.01 means there is 0.01g of alcohol in 100ml of your blood.

In an average, healthy person, one standard drink:

• increases BAC by about 0.02
• takes about one hour to break down.

But remember, this can be different for everyone.

BAC is what police test for in roadside alcohol breath tests. If you're a fully licensed driver, you're breaking the law in Australia if you drive with a equal to or more than 0.05.

How long alcohol stays in your blood

Drinking more than one standard drink per hour will increase your BAC. The faster you drink, the higher your BAC.

When you stop drinking, your BAC will keep rising as the alcohol in your stomach goes into your blood.

The only way to lower your BAC is time. The more drinks you have, the more time you need.

You cannot remove alcohol from your blood by vomiting, having a cold shower or drinking coffee.

Short-term effects

Drinking alcohol can affect your body straight away. A healthy person is likely to experience the following:

• BAC of up to 0.05:
  • feeling of wellbeing
  • talkative, relaxed and more confident
• BAC of 0.05 to 0.08:
  • impaired judgement and movement
  • reduced inhibitions
• BAC of 0.08 to 0.15:
  • slurred speech
  • impaired balance, coordination, vision and reflexes
  • unstable emotions
  • nausea and vomiting
• BAC of 0.15 to 0.30:
  • unable to walk without help
  • sleepy
  • difficulty breathing
  • memory loss
  • loss of bladder control
  • possible loss of consciousness
• BAC of over 0.30:
  • coma
  • death.

In the short term, drinking too much alcohol can also lead to:

• accidental injury (to yourself or others)
• being in a road accident
• deliberately harming yourself or others
• risky sexual behaviour
• family, domestic and sexual violence
• alcohol poisoning
• hangovers.

Binge drinking (drinking a lot of alcohol in one session or a short period) can be even more harmful and risky.

Long-term effects

For both men and women, the risk of dying from alcohol-related disease and injury remains below 1 in 100 if no more than 10 standard drinks are consumed each week and no more than 4 standard drinks are consumed on any one day. The less you drink, the lower your risk of harm from alcohol.

Long-term effects of alcohol consumption above Guideline recommendations include:

• mental health issues such as increased risk of suicide
• substance abuse — you may become dependent or addicted to alcohol, especially if you have depression or anxiety, or a family history of alcohol dependence
• increased risk of diabetes and weight gain
• impotence and other problems with sexual performance
• cancers such as stomach cancer, bowel cancer, breast cancer, mouth cancer, throat cancer, oesophageal cancer and liver cancer
• fertility issues such as reduced sperm count and reduced testosterone levels in men
• brain damage and brain-related conditions such as stroke and dementia
• heart issues such as high blood pressure, heart damage and heart attacks
• cirrhosis of the liver and liver failure.

If you’re pregnant, or planning a pregnancy, you should not drink alcohol. If you are breastfeeding, not drinking alcohol is safest for your baby. Drinking any amount of alcohol can harm your fetus (unborn baby) or baby.

Social and financial problems

Alcohol can reduce your inhibitions and lead you to behave in a way you normally wouldn’t. You may commit a crime, behave in an antisocial way or do something embarrassing.

Your behaviour could affect your friendships, your work and your family.

If you drink a lot or become dependent on alcohol, you could end up spending a lot of money on your drinking.

Taking alcohol with other drugs

Drinking alcohol at the same time as taking other drugs, including medicine, can be very risky. This is because alcohol can:

• increase the side effects of other drugs
• reduce the effect of medicine such as antibiotics or diabetes medicine
• hide the effect of a drug or medicine.

Reducing the effects

To reduce the effects of your drinking:

• take a look at the guidelines to reduce your risk
• find out how you can reduce or quit alcohol.

Last updated: 

2 August 2022

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