Alcohol: how long does it stay in the blood?
About 6 hours (in the blood)
The liver can break down most of a standard smallish drink in an hour. But some of it stays in the blood for a lot longer as described below.
A standard drink (a unit of alcohol) is defined as:
- 1/2 pint of beer or cider
- A small glass of wine
- A shot of spirits (gin, rum, tequila, vodka, whisky).
But (the big BUT). The amount of time any alcohol can be detected in your system depends on the type of test, as shown in the following table.
How long does alcohol stay in your system? – i.e total time?
Time in body system
Blood 6 Hours
Breath 12-24 Hours (Breathalyzer)
Urine 12-24 Hours; 72 hours or more for newer test methods
Saliva 12-24 Hours
Hair 90 Days
How long does it take for alcohol to kick in?
People will generally experience the effects of a drink within 15 to 45 minutes. Yes, it is quite rapidly absorbed. Alcohol is then broken down predominantly in the liver through the actions of an enzyme called alcohol dehydrogenase.
How much can you drink if you are going to drive?
Even a small amount of alcohol can affect your vision, reaction times and ability to drive, even if you remain well below the legal drink-drive limit of 80 milligrams per 100 millilitres.
So the easiest way to make sure you remain safe behind the wheel is to simply not drink any alcohol at all if you intend to drive.
How do you know when you are drunk?
The higher your blood alcohol level, the more likely you will be to display signs of intoxication, which include:
- Lowered inhibitions
- Slurred speech
- Impaired coordination (as it affects the inner ear and cerebellum)
- Confusion
- Trouble remembering things
- Difficulty concentrating
- Breathing problems (e.g. decreased respiratory effort, respiratory depression).
People who are drunk are also more at risk for
- Road traffic accidents
- Risky behaviour, such as unprotected sex
- Violence and suicide
- Attendance at Accident & Emergency Departments. These are very busy and often not a great place for people who are drunk; as if you are not very ill, you will not be prioritised, so will be there for many hours.
Summary
We have explained how long does it take for alcohol to get out of your system. For one smallish drink, most of it lasts about an hour. But some of it stays in the blood for a lot longer. We hope this has been helpful.
Other resource
This very good page on the NHS website describes the effects of variable amounts of alcohol.
