What is it?

Alcohol is the common name for ethyl alcohol. It’s a Central Nervous System depressant and is one of the most widely used (and abused) drugs in our society. It’s produced by the fermentation of fruits, vegetables or grains by yeasts which converts the carbohydrates (sugars) of these plants to ethyl alcohol. Alcoholic drinks consist mainly of various strength mixtures of water and ethyl alcohol.

Medicinal uses

Alcohol is sometimes used as an external local anaesthetic and sterilising agent.

How does it work?

Alcohol depresses parts of the central nervous system – it slows down some of our brain functions. Various parts of the central nervous system are depressed by alcohol, with all sorts of consequences. For example, when the brain’s speech centres are inhibited, this causes slurred speech; when the vision centres are affected this produces distorted vision; when the co-ordination centres are depressed this results in loss of balance and limb control.

The strong depressant effect of alcohol lasts for a few hours after drinking, but alcohol also produces a weaker agitation (or irritation) of the nervous system that lasts much longer. This is the cause of the “morning after” hangover and shakiness. It’s due to the irritation of the nervous system by alcohol drunk many hours before.
This effect often leads heavy evening drinkers to drink again the next morning, as the (very uncomfortable) agitation can be temporarily overcome by drinking more alcohol. Thus, a vicious circle is set in motion, which can play a large part in alcoholic drinking patterns.

What effect does it have?

The impact of drinking alcohol depends on the state of the brain at the time, and this in turn depends on the drinking environment.

In a quiet environment (little brain activity), perhaps at home in an armchair, an alcohol user will experience relaxation or drowsiness at low to moderate doses.

In a social setting, with lots of sights, sounds and social interaction (lots of brain activity) low doses of alcohol may feel stimulating. This is caused by depression of the higher brain centres, which produces apparent stimulation by reducing anxiety and self-consciousness. A drinker may become more talkative than normal and demonstrate increased self-confidence and loss of self restraint. So alcohol can feel like a stimulant – but it’s not – these effects are a result of the inhibition of normal brain activity.

As the alcohol dose is increased, significant depression of brain activity can result in slurred speech, loss of limb co-ordination and loss of emotional control. High doses of alcohol can inhibit vital brain functions – this can produce deep sedation and slow down the breathing rate, which can result in coma or death.

Alcohol Alcohol intake is measured in units. One unit is is roughly equal to half a pint of normal strength beer/lager/cider, a glass of wine or a pub measure of spirits. The list below shows the effect of drinking various amounts of alcohol and also indicates blood alcohol concentration (as mg alcohol per 100ml blood), as this determines whether an offence is committed by driving a motor vehicle. The current UK alcohol limit for driving is 80mg/100ml.

It’s important to remember that the concentration of alcohol in the blood and its effects depend on a number of factors including body weight, type of drink, drinking environment, previous exposure to alcohol, stomach contents and sex of the drinker.
Alcohol has its strongest effect on women. This is because women’s generally lower body weight means (for equal amounts drunk) they take in more alcohol per pound weight and also, as the female body contains less blood volume, the same amount drunk will produce a higher blood alcohol concentration in a woman than in a man.

  • After 1 to 2 units (0.5 to 1 pint of beer – or 20-50mg/100ml) there is not much effect, beside a slight intensification of mood.
  • After 3 to 4 units (1.5 to 2 pints of beer – or 50-80mg/100ml) there is usually a feeling of relaxation and mild sedation. There may be a slight impairment of steady movement. This is the legal limit for driving a vehicle and in fact 4 units of alcohol could put some people over the 80 mg/100ml legal blood alcohol limit.
  • After 5 to 6 units (2.5 to 3 pints of beer – or 80-100mg/100ml) there is usually some loss of physical and mental co-ordination. Judgement and memory may be affected, particularly the ability to concentrate.
  • After 7 to 8 units (3.5 to 4 pints of beer – or 120-200mg/100ml) most people slur their speech and are likely to have some difficulty in standing or walking. This level of intoxication can result in irresponsible behaviour and euphoria.
  • After drinking 15 to 20 units (7 to 10 pints of beer – or 200-300mg/100ml) most people will have passed out.

Consequences of alcohol abuse

Most people will have some experience with alcohol. Many will experiment and stop, or continue to drink casually without significant adverse effects. Some people will use alcohol regularly, with varying degrees of physical, emotional and social problems. Some will develop a dependency and be destructive to themselves and others for many years. Some will die – and some will cause others to die.

As there is no certain way to predict which alcohol drinkers will develop serious problems, all alcohol use must be considered as potentially dangerous.

Alcohol Dependence

Alcohol drinkers may develop a physical or psychological dependence on alcohol. This can cause great harm to the drinker, in terms of physical and mental health, financial problems, employment difficulties etc. In addition, alcohol dependence is likely to cause great distress to partners, children or other family members, who may be directly or indirectly exposed to the consequences arising from compulsive alcohol consumption.
Physical dependence is often related to consistently heavy drinking. People who drink on a regular basis become tolerant to many of the unpleasant effects of alcohol and are able to drink more before suffering these effects. Many heavy drinkers may not appear to be drunk. Because they continue to work and socialize reasonably well, harm to their physical health can go unrecognized until severe damage develops – or until they are unable to drink for some reason and suddenly experience alcohol withdrawal symptoms. These symptoms range from jumpiness, sleeplessness, sweating, and poor appetite, to tremors (the “shakes”), convulsions, hallucinations and sometimes death.
Deaths from suicide, accident and cirrhosis of the liver are very common among heavy drinkers.

Psychological dependence upon alcohol may occur with regular use of even quite small daily amounts, such as a glass or two of sherry. It can also occur in people who drink alcohol only under certain conditions, such as before and during social occasions. This form of dependence results from a craving for alcohol’s psychological effects, such as relief from anxiety, although the drinker may not consume amounts that produce serious intoxication. For psychologically dependent drinkers, lack of alcohol tends to make them anxious and prone to panic attacks.

Damage to health

The UK Government-recommended alcohol limits are presently 21 units per week for men (10.5 pints of beer) and 14 units per week for women (7 pints of beer). Sustained drinking in excess of this level increases the chance of damaging our health. This can take the form of liver disease, stomach ulcers, heart and circulation disorders – and in extreme cases brain damage.
25,000 people die in the UK each year from alcohol-related illnesses – this is 50 times the annual rate of death from all illicit drugs put together!

Family abuse

Excessive consumption of alcohol is commonly sited as a reason for difficulties within a family or within a marriage. These may range from drunken violence directed toward a spouse or children, to financial problems caused by compulsive purchase of alcohol or otherwise related to that.
It is difficult to over-emphasise just how much stress a person who abuses alcohol may cause within his or her immediate family. If a person continues to abuse alcohol over a period of time, his or her behaviour is likely to cause bitterness and resentment among relatives. While family members may love the alcohol abuser, they are likely to hate his or her behaviour.
Eventually – the love dies.


While a person is under the influence of alcohol he or she is far more likely to have an accident than while sober because alcohol adversely affects judgement and perception. Thirty percent of vehicle drivers killed in road accidents within the UK were found to have been drinking alcohol beforehand. Many of those who died in such a manner may well have caused the death or injury of other road users. What a waste.