What actually is alcohol?
The alcohol in alcoholic drinks is ethanol, sometimes called ethyl alcohol. Its chemical formula is C₂H₅OH. It is a colourless liquid made from carbon, hydrogen and oxygen.
There are other kinds of alcohol used in industry and household products, but they are not the alcohol intended for drinking. When we talk about alcohol in beer, wine or spirits, we mean ethanol.
How is alcohol made?
Alcoholic drinks begin with fermentation. Yeast feeds on sugars and produces ethanol and carbon dioxide.
The source of the sugar helps determine the drink: grapes are used for wine, grains for many beers and spirits, and apples for cider.
Spirits go through an additional process called distillation. This concentrates the alcohol, which is why spirits usually contain a much higher percentage of alcohol than beer or wine.
How much alcohol is in different drinks?
The amount varies enormously. A beer or cider may be around 4–5% alcohol by volume, wine around 12–14%, and many spirits around 40%. There are weaker and much stronger versions of all of these, so the label matters more than the type of drink.
The size of the drink matters too. A large glass of wine can contain more alcohol than a small measure of spirits even though the wine has a lower percentage of alcohol.
What does ABV mean?
ABV means alcohol by volume. It tells you what percentage of the liquid is pure alcohol.
A wine labelled 12% ABV contains 12 ml of pure alcohol in every 100 ml of wine. A 40% spirit contains 40 ml in every 100 ml.
ABV tells you the strength of the drink. To know how much alcohol someone has actually consumed, you also need to know how much they drank.
What is a unit of alcohol?
In the UK, one unit is 10 ml, or 8 grams, of pure alcohol. Units make it possible to compare drinks of different sizes and strengths.
You can calculate the units in a drink by multiplying its volume in millilitres by its ABV and dividing by 1,000. A 25 ml measure of 40% spirit is one unit. A 175 ml glass of 12% wine contains 2.1 units.
Other countries may use a different definition of a standard drink, so a 'drink' or 'unit' does not always mean the same amount of alcohol everywhere.
Is the alcohol in beer different from the alcohol in wine or spirits?
No. The intoxicating alcohol is ethanol in all of them.
What changes is the concentration, the ingredients used to make the drink, the serving size and how quickly it is consumed. Forty per cent whisky does not contain a more powerful kind of alcohol than 12% wine; it contains a higher concentration of the same alcohol.
What happens to alcohol after someone drinks it?
Alcohol passes from the stomach and intestines into the bloodstream. The blood then carries it throughout the body, including to the brain.
Alcohol is absorbed faster than the body can break it down. If someone keeps drinking before the alcohol already in their body has been processed, the amount of alcohol in their blood rises.
How does the body break alcohol down?
Most alcohol is broken down in the liver. An enzyme called alcohol dehydrogenase changes ethanol into acetaldehyde, which is toxic. Another enzyme then changes acetaldehyde into acetate, which can be broken down further by the body.
This process takes time. The body cannot suddenly speed it up because someone wants to become sober.
Will coffee, food or a cold shower sober someone up?
No. Coffee may make someone feel more awake and a cold shower may make them feel more alert, but neither removes alcohol from the bloodstream.
Food can slow the absorption of alcohol when it is eaten before or while drinking, but it cannot remove alcohol that has already been absorbed. Ultimately, the body needs time to process the alcohol.