A few hours after the last glass of alcohol, the blood alcohol level drops to zero. But frequent alcohol consumption is still detectable in the blood for a long time.
When a person drinks alcohol, it quickly enters the bloodstream through the lining of their mouth, stomach, and small intestine, and from there spreads throughout their body. The alcohol content in the blood can therefore be used to prove consumption quite quickly – depending on the level for many hours.
How quickly does alcohol break down?
The alcohol concentration in the blood is given in parts per thousand. One per thousand corresponds to one gram of alcohol per kilogram of blood. After you stop drinking alcohol, your blood alcohol level drops because the liver metabolizes the alcohol in your blood. In other words, it breaks it down into other substances that the body can use.
How long it takes for the blood alcohol level to drop back to 0 depends primarily on how high the level was originally – i.e. how much alcohol the drunk person has had.
Would you like to know how much alcohol is in your blood? Our blood alcohol calculator gives you an estimate.
The rule of thumb is: around 0.15 per mille is broken down per hour. If someone had a blood alcohol level of one per thousand, it takes about seven hours until he or she is sober again. However, women usually take a little longer to sober up than men.
Good to know: The first signs of intoxication are usually noticeable from a blood alcohol level of around 0.5. Above 1.5 per mille, risky symptoms often set in. From 2.5 per mil experts speak of severe alcohol poisoning.
How long is alcohol detectable in the blood?
The alcohol itself, also called ethanol, is only detectable in the blood for a few hours, or for a day in the case of severe alcohol intoxication.
However, if someone drinks too much alcohol over a long period of time, this can show up in other values in the blood, including the so-called liver values. Excessive alcohol consumption damages the liver. As a result, this increasingly releases certain proteins from its tissue into the blood, which are also referred to as liver enzymes.
Long-term excessive alcohol consumption can raise liver enzymes and certain other blood tests for weeks or even months. You can find out more about this in our article “How Alcohol Affects Liver Values”.
