The immediate effect of alcohol

Alcohol dampens the brain’s arousal, motor and sensory centres, dampening reactions to stimuli and affecting coordination, speech, cognition and the senses. The first potentially adverse effect of alcohol consumption is loss of fine motor skills and inhibitions.

A blood alcohol concentration (BAC) of about 0.05 g/100 ml (or 0.05%), which is the legal limit for driving in Australia, was based on controlled studies testing driving skills (Transport and Road Research Laboratory 1987). Above this BAC performance, behaviour and physical health deteriorate progressively (see Section 3.3 for further discussion of BACs).

If the BAC reaches a high enough level it leads to unconsciousness and, eventually, inhibition of normal breathing. This may be fatal, particularly as the person may vomit and can inhale vomit and suffocate. Alcohol also affects the pituitary gland at the base of the brain, suppressing the production of a hormone that keeps the body’s fluid reserves in balance. The kidneys fail to reabsorb an adequate amount of water, and the body excretes more water than it takes in, leaving the person dehydrated and with a headache.

As alcohol intake increases, both skills and inhibitions decrease and therefore risky behaviour, injuries and trauma increase. Also, without the cognitive or verbal capacity to resolve conflicts, physical violence becomes more likely.

The immediate effects of alcohol on the brain are often less apparent in people who drink regularly, as they acquire a degree of tolerance. Tolerance occurs because the liver becomes more efficient at breaking down alcohol. The person learns to cope with, and compensate for, the deficits induced by alcohol. Despite this tolerance, the long-term effects remain damaging, particularly as the drinkers who have greater tolerance for alcohol are those who subject themselves to higher blood alcohol levels more frequently.

There are no safe levels of alcohol consumption because of the different ways alcohol can affect people. Women are generally affected by alcohol more than men because of the differences in the way their bodies process alcohol. Basically the more alcohol you consume the higher the risk of harm.

People choosing to consume alcohol must be aware that there is always a potential of harm both short and long term to their health and social wellbeing.