What are the effects of alcohol?

Alcohol is a drug that impacts the body in a number of ways. Most people know this generally – but some of the ways may surprise you.

Alcohol is a drug that has immediate effects, but also has an influence on the body over the long term. For more info, please talk to your GP or consult the alcohol guidelines from the National Health & Medical Research Council.

Immediate effects on our body

When we first have a drink, our brains begin producing the ‘feel-good’ chemical, dopamine – which is responsible for giving us a feeling of euphoria. At the same time, the brain produces a neurochemical called GABA, which gives us the feeling of relaxation. Alcohol is also a depressant drug – after a few more drinks, this may cause us to become a little too relaxed, and clumsy as a result.

Alcohol also increases the effect of GABA, which is associated with dampening our reflexes and response times. It suppresses the parts of the brain responsible for control and inhibition, so you may make decisions you wouldn’t tend to make when sober. This is why drinking and driving is such a dangerous combination – it only takes one bad decision for a life-changing accident to occur. 

Some people may also find it especially hard to stop drinking once their Blood Alcohol Content (BAC) is above a certain level, and this seems to be driven by our genetics as well.

While all the above is happening, the liver is working to process all of the alcohol to get it out of your body. Alcohol affects an antidiuretic hormone in the body, which will cause the body to want to get rid of more liquid than it is taking in. This causes the dehydration that causes the hangovers the next morning. There may also be increased sexual desire, but an often decreased ability to do much about this.

Longer-term effects

Here, we’re talking about the cumulative effects that drinking over a long period of time will have. Regular, habitual drinking has been associated with a number of chronic diseases.

Cardiovascular Disease

Consumption of larger amounts of alcohol over time is harmful for the cardiovascular system, and is associated with cardiovascular death, heart failure, stroke, high blood pressure/cholesterol, and diabetes.1


Alcohol is considered a group 1 carcinogen, which means there is sufficient evidence to say that it causes cancer in humans. Alcohol is linked to a number of cancers, including colorectal, liver and female breast cancer.2 There also seems to be a positive association between alcohol and pancreatic cancer in people drinking more than two standard drinks per day.3


The chance of developing type 2 diabetes increases for high-level drinkers compared to current and lifetime abstainers from alcohol.4

Nutrition-related conditions

Alcohol can interfere with an individual’s nutritional status by affecting the digestion, storage, use and excretion of nutrients. High levels of alcohol consumption are linked to a number of different forms of malnutrition.5

Weight Gain

Although alcohol is not necessarily associated with weight gain directly, it is high in calories, it can make you hungry, and it also lowers your inhibitions. So it’s more likely that you will be tempted by fast food and therefore gain weight.6

Liver diseases

Alcohol consumption over many years can cause fatty liver disease and cirrhosis of the liver, both of which can have serious consequences for your overall health. Essentially, cirrhosis is a condition where the functioning liver cells have been replaced by scar tissue due to extensive damage, and the liver cannot function properly. The risk of cirrhosis increases in proportion to the amount drunk and the period of time spent doing so.7

Mental health conditions:

There’s a well-documented relationship between heavier alcohol consumption and mental health issues. Alcohol use increases the risk of conditions such as depression and anxiety8, and people with pre-existing mental health conditions are more at risk of using alcohol in a hazardous way.9 As such, the combination of alcohol consumption and depression can also increase the risk of suicidal behaviour.10 The effectiveness of antidepressant medications can also be affected by alcohol use.11


Regular drinkers can acquire a degree of tolerance and give the appearance of being less affected by drinking. However, the brain will gradually  need more and more alcohol in order to feel that same ‘buzz’.

Despite this tolerance, the long-term effects of alcohol remain damaging, particularly since people who have greater tolerance for alcohol are likely to be those who drink more frequently.

Cognitive impairment

High levels of drinking over the short- or long term are associated with cognitive impairment. People who consume alcohol at harmful levels over the long term have damaging structural and metabolic brain changes and an increased risk of dementia.12 

Other effects of alcohol

Effects on older people

As we age, the effects of alcohol become more pronounced. People over the age of 50 have decreased levels of body water content and chemicals that break down alcohol in the body (gastric alcohol dehydrogenase). This means that alcohol will remain in your body for longer periods of time as it is not being broken down as quickly, leading to a prolonged and more rapid feeling of being tipsy. This can be a real problem for older people, as it places them at greater risk of accidental falls and inadvertent drink driving.

Read more here

Risks to babies during pregnancy and after birth:

Drinking alcohol while pregnant will result in alcohol entering the bloodstream of the fetus, and that directly increases the risk of a range of birth defects, and growth and developmental problems, known as Fetal Alcohol Spectrum Disorder. 

Alcohol also enters the breast milk, and can interfere with breastfeeding and infant behaviour. 

Read more here

Effects on our sleep

Alcohol increases sympathetic activity in our brains and can disrupt our sleep, particularly during the second part of the night. REM sleep is the deep and restorative ‘quality’ sleep that helps us to feel rested and alert. Consuming alcohol inhibits REM sleep – the more alcohol we consume, the less REM sleep we get. 

Alcohol can have a stimulating or sedating effect depending on how much, and when, we drink. In fact, even drinking in the late afternoon or up to six hours before bedtime can disrupt our sleep, even if the alcohol is no longer in our bloodstream.

Just as with other short-acting sedatives, ‘rebound’ occurs and we can experience heightened arousal 2–3 hours after blood-alcohol concentrations fall close to zero; this can result in those early morning awakenings where it is hard to return to sleep. This ‘rebound’ can also be associated with intensive dreaming or nightmares – contributing to disrupted sleep.

We can quickly develop a tolerance to alcohol’s effect on our sleep, so that while we are not necessarily noticing these sleep disruptions, the quality and pattern of our sleep cycle is being affected each time we drink alcohol, and this becomes our ‘new normal’.

Effects on our fertility

For women, heavy drinking affects fertility, increasing the length of time it takes to get pregnant and reducing the chances of having a healthy baby.13 For men, heavy alcohol use reduces men’s fertility. It can cause impotence, reduced libido and affects sperm quality.14 Although the scientific evidence on how low-to-moderate drinking affects a man’s fertility isn’t clear, the National Health and Medical Research Council recommends that men abide by the safe drinking guidelines and women don’t drink at all during this period.

Effects on our sex lives

People who have ongoing issues with intimacy might be more likely to use alcohol regularly as a way to make sex more comfortable for themselves – reducing their levels of anxiety and self-consciousness. But unfortunately, alcohol can also affect their own ability to feel pleasure. 

It’s a tricky line to walk, since alcohol can ‘release the brakes’ and lower inhibitions – but at the same time blunt some of the good stuff too. Alcohol causes our brains to release GABA (the calming chemical) and block glutamate (anxiety causing chemical), as well as lower our inhibitions (by affecting our prefrontal cortex, or our ‘internal policeman’). Other substances affect the dopamine and serotonin systems in our brains, making us more open and loving.

  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5513687/
  2. https://canceraustralia.gov.au/publications-and-resources/position-statements/lifestyle-risk-factors-and-primary-prevention-cancer/lifestyle-risk-factors/alcohol
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3574589/
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2768203/
  5. https://pubs.niaaa.nih.gov/publications/arh27-3/220-231.htm
  6. https://www.betterhealth.vic.gov.au/health/HealthyLiving/Alcohol-and-weight-gain
  7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5513682/
  8. Mental Health Foundation. (2006). Cheers? Understanding the relationship between alcohol and mental health. Retrieved from: https://www.mentalhealth.org.uk/publications/cheers-understanding-relationship-between-alcohol-and-mental-health
  9. National Health and Medical Research Council. (2009). Australian Guidelines to reduce health risks from drinking alcohol. Canberra, ACT: Commonwealth of Australia.
  10. Brady, J. (2006). The association between alcohol misuse and suicidal behaviour. Alcohol & Alcoholism, 41(5), 473-478.
  12. Alzheimer’s Disease International (2014). The World Alzheimer Report 2014, Dementia and Risk Reduction: An analysis of protective and modifiable factors. Retrieved from https://www.alz.co.uk/research/world-report-2014
  14. https://www.yourfertility.org.au/everyone/lifestyle/alcohol


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