Effects on the body

Alcohol affects all parts of the body.

It particularly affects:

Long-term effects of alcohol use
Chronic heavy alcohol use can cause abnormalities in the blood, leading to anaemia (low haemoglobin, the component of blood that carries oxygen around the body) and low platelets (platelets help prevent bleeding).13 Chronic heavy alcohol use also suppresses the immune system (such as affecting the white blood cells that fight infections), making it more difficult for the body to fight off both viral and bacterial infections. People who drink heavily over a long time are more likely to suffer from infections after surgery, burns, trauma, hepatitis C infection, HIV/AIDS, meningitis, tuberculosis and pneumonia (acute inflammation of the lung, usually due to infection).4,14,15
Immediate effects of alcohol use

Alcohol use causes many different types of injuries, including injuries from road traffic accidents, assaults and falls.9 This is usually because high levels of blood alcohol impair the brain’s thought processes and the coordination of muscles, causing clumsiness and difficulty walking.16 Common injuries seen at the emergency department include cuts, bruises, sprains and broken bones.17,18 The risk of injury in the six hours after drinking doubles with four standard drinks and increases rapidly the more alcohol is drunk on a single occasion.19

Long-term effects of alcohol use

Moderate alcohol use may protect against osteoporosis (thinning of the bones, which makes the bones more likely to break).20 However, chronic heavy alcohol use interferes with the absorption of calcium and bone formation and can actually lead to steoporosis.20,21 Chronic heavy use is also associated with a painful condition where bone tissue dies (osteonecrosis)22, gout (a type of arthritis or inflammation of the joints, often affecting the joint of the big toe)13, and muscle wasting and weakness.4,23

Immediate effects of alcohol use

Being drunk impairs judgment, inhibitions and concentration and in increasing amounts leads to drowsiness and coma.4 The loss of memory for a period of drunkenness (alcoholic blackout) can occur in occasional as well as regular heavy drinkers and is due to alcohol interfering with the laying down of memories.4,8

Long-term effects of alcohol use

Chronic heavy alcohol use can damage the brain and nerves in a variety of ways. Some damage to the brain, from mild to severe, occurs in around half of chronic heavy alcohol drinkers.24 This may be a result of thiamine (vitamin B1) deficiency (secondary to alcohol use, either because of poor diet or because alcohol reduces the absorption of thiamine from the gut and interferes with how thiamine is used in the body).25

Thiamine deficiency can cause an acute, severe, life-threatening disorder called Wernicke’s encephalopathy, which usually presents with symptoms of abnormal or paralysed eye movements, difficulty walking and confusion. It also causes a chronic condition of memory loss (variously called Korsakoff’s syndrome, psychosis or dementia), where loss of old memories occurs and difficulties in laying down new memories may be profound.4,24,25 Both of these disorders are ultimately fatal without treatment with thiamine.4

Chronic heavy alcohol use can also damage the part of the brain responsible for balance and coordination (the cerebellum), leading to instability and problems with walking.4,25 It can also damage peripheral nerves in the body, leading to pain, weakness, numbness and the inability to sense touch.4,26 In rare cases it can damage specific centres in the brain, leading to loss of mental function, inability to walk and death8 and can lead to the development of epilepsy (chronic fits)9 and sleep disturbances. Although individuals suffering from insomnia sometimes use alcohol to treat the insomnia, tolerance to the sedating effect of alcohol is likely to occur, increasing the risk of excessive use.3

Also, if more than one or two drinks are taken in the evening, sleep can be disrupted, increasing the chances of a person waking in the night and finding it hard to fall back asleep.8

The relationship between alcohol use and stroke, where there is a sudden paralysis, loss of sensation or inability to talk because the blood supply to the brain is interrupted, is complex. Alcohol increases the risk of hemorrhagic stroke, where the stroke is caused by bleeding in the brain. However, low to moderate alcohol use (one to two drinks a day) reduces the risk of ischaemic stroke, which is caused by blockage of the blood vessels in the brain, but higher levels of alcohol use increase the risk of ischaemic stroke.9

Long-term effects of alcohol use

Long-term alcohol use increases the risk of breast cancer, with higher use resulting in a higher risk of cancer.9,27,28 A significantly elevated risk is seen even from having one or two drinks of alcohol a day.10 The risk increases on average by about 10% for every one standard drink of alcohol per day.29

Immediate effects of alcohol use

Being drunk can cause blurred or double vision.4

Long-term effects of alcohol use

Chronic heavy alcohol use, when coupled with a diet low in vitamin B1 and B12, may lead to decreased vision.4,30

The evidence for the effects of alcohol on the heart is mixed and often controversial. This section is a brief summary of the evidence available at the time of publication.

Long-term effects of alcohol use

There is an opinion that light to moderate alcohol use (up to one standard drink per day for women and up to two standard drinks per day for men) can, in older age groups, reduce the risk of developing and dying from coronary artery disease (narrowing and blockage of the arteries supplying blood to the heart resulting from the build up of fatty deposits inside the walls of the arteries (atherosclerosis), which can cause angina and heart attacks). This appears to be because small quantities of alcohol alter the lipids and clotting factors in the blood to make them protective against heart disease. 9,31,32,33

However, heavy drinking (both chronic and a pattern of heavy drinking sessions) increases the risk of coronary artery disease.9,34 Heavy drinking (chronic and/or at a single session) is also associated with sudden death from heart failure, irregular heartbeats and chronic disease of the heart muscle (dilated cardiomyopathy). Dilated cardiomyopathy leads to heart failure, where the heart can no longer pump blood around the body effectively. 9,27,32,34

Heavy chronic alcohol use is also linked to high blood pressure, particularly in men.9,34,35 Blood pressure increases with drinking more than two or three drinks a day on average and restriction of alcohol lowers the blood pressure.35

Drinking alcohol in order to ‘protect the heart’ is not advisable, since alcohol is an addictive drug that causes cancer, increases the risk of injury and causes damage to the fetus in pregnant women. People can find it difficult to limit their drinking to one or two standard drinks a day and heavy drinking actually increases the risk of heart disease. 34 People who have risk factors for, or have, established heart disease should also focus on other factors such as cigarette smoking, high cholesterol, high blood pressure, diabetes, overweight and physical inactivity. Young and middle-aged adults, especially women, are more likely to experience harm than benefit from alcohol use due to risk from injury and, for women, increased risk from breast cancer.36,37

Long-term effects of alcohol use

Long-term alcohol use can cause cancer of the large bowel and rectum.9,38,39 Alcohol can lead to malnutrition and diseases due to low vitamin levels, as it blocks the absorption of many important vitamins and nutrients in the gut.23

Immediate effects of alcohol use

Alcohol is a diuretic, meaning that it causes water to be lost from the body through the kidneys (into urine), which can lead to dehydration.35 Alcohol can also cause the loss of important minerals and salts from the body such as magnesium, calcium, phosphate, sodium and potassium13, either directly or because alcohol induces vomiting. Low levels of these elements can cause many problems ranging from irregular heartbeats to seizures.5

Long-term effects of alcohol use

Chronic heavy alcohol use can damage the liver, causing alcoholic liver disease. This occurs across a spectrum from fatty liver, to acute alcoholic hepatitis, to cirrhosis.1

Fatty liver, where fat builds up in the liver cells, is very common in heavy drinkers and is reversible if drinking is reduced. However, a small percentage of people with fatty liver will develop alcoholic hepatitis, cirrhosis or liver cancer.

Alcoholic hepatitis develops in 10% to 35% of heavy drinkers and is an acute injury to the liver that can present with symptoms of feeling unwell, tiredness, jaundice (yellow skin and whites of eyes), swollen stomach and enlarged tender liver. Death from liver failure can occur in severe cases.

Cirrhosis of the liver develops in 5% to15% of heavy drinkers and is where the liver is permanently damaged and replaced by scar tissue, so the liver can no longer function (to detoxify the body, make vital proteins, store vitamins and sugars, and make chemicals necessary for digestion). Cirrhosis can also lead to death from liver failure.

Treatment for alcoholic liver disease must include stopping the drinking of alcohol. Alcohol also causes liver cancer, and treatment options are often limited due to the presence of alcoholic liver disease or the cancer having spread widely by the time of diagnosis. This means liver cancer is often quickly fatal.9,40,41

Immediate effects of alcohol use

Being drunk 9 increases the risk of pneumonia (inflammation of the lungs, usually due to infection from bacteria or viruses).5 This is because at high blood concentrations, alcohol is sedating and relaxes the mouth and throat, suppresses reflexes (like the gag and cough reflexes), and reduces the ability of the lungs to clear mucus and foreign matter, so that vomit, saliva or other substances may enter the lungs and cause inflammation and infection (bronchitis or pneumonia).

Long-term effects of alcohol use

Chronic heavy alcohol use  is also associated with higher rates of pneumonia, tuberculosis (an infectious disease that primarily affects the lungs but also any other part of the body)9, and acute respiratory distress syndrome (ARDS – a life-threatening condition in which the lungs fill with fluid, which occurs as a rare complication of pneumonia, trauma and severe infections).42 In addition to ways in which acute alcohol use can cause pneumonia, chronic heavy alcohol use also impairs the immune system and changes the bacteria present in the mouth to those more likely to cause infections, making people more vulnerable to pneumonia.9

Immediate effects of alcohol use

Many people use low doses of alcohol for relaxation and to relieve tension, nervousness and stress.2,8 However, in some people alcohol creates rather than reduces stress through stimulating stress hormones.43 Alcohol affects mood in a variety of ways and can make people feel happy, sad or aggressive, and can also make moods swing.4,8 However, there is a risk of becoming dependent on alcohol if it is used as a primary means to relieve stress and anxiety without addressing the underlying causes. Because alcohol removes inhibitions and increases aggression and recklessness, alcohol is often found in the blood of people who self-harm, or attempt or complete suicide.44

Long-term effects of alcohol use

Alcohol is addictive and can lead to dependency. This is where the body requires more alcohol to achieve the desired effect (eg, altered mood), where use of alcohol interferes with a person’s life (causing legal, work/study, relationship or social problems), where a person continues to use alcohol despite alcohol causing physical or mental problems and, if alcohol is not taken, withdrawal symptoms occur.

The severity of withdrawal symptoms depends on the quantity of alcohol consumed and the length of the drinking session. Symptoms including shaking of the hands, which commonly occurs the morning after the drinking session and may be relieved by more alcohol. If alcohol is not taken, symptoms can progress to insomnia, increased heart rate, temperature and blood pressure, sweating, agitation, nausea, flushing of the face, nightmares, hallucinations (seeing, hearing or feeling things that are not present) and fits.4,13,45,46 The most serious withdrawal syndrome is ‘delirium tremens’, which develops in about 5% of people with alcohol withdrawal (more if fits are not treated) and by definition includes the symptom of delirium (an altered and confused state of mind).46 This syndrome has a death rate of around 5%.46

In people who drink heavily, alcohol commonly causes mood disorders, including depression, anxiety and psychosis (a mental illness defined by changes in personality, a distorted sense of reality, and delusions).8 If these disorders only occur during drinking sessions or withdrawal, they will usually resolve once drinking is stopped.8 Alcohol abuse and dependency are also common in people with pre-existing mental health conditions.

Immediate effects of alcohol use

Being drunk can have various effects on speech, such as making people more friendly, talkative, unreserved, relaxed or argumentative. Increasing amounts of alcohol can cause aggressive, antisocial, angry, slurred and confused speech.4,5

Long-term effects of alcohol use

Alcohol is a carcinogen, meaning that it causes cancers in humans. Regular alcohol use increases the risk of cancers of the mouth, throat and voicebox.9,29,47 Drinking around 50g of alcohol a day (five standard drinks) increases the risk of these cancers by two to three times compared with non-drinkers, but for people who smoke, this risk is increased much more.10,47 Drinking more increases the risk of cancers, and drinking less decreases the risk of cancers.

Immediate effects of alcohol use

Heavy alcohol use on a single occasion can lead to dangerously low blood sugar (hypoglycaemia), which can cause symptoms of shaking, sweating, dizziness, blurred vision and, if not treated, brain damage.4,5

Long-term effects of alcohol use

The pancreas is a gland that secretes digestive enzymes and releases insulin, which regulates sugar levels in the blood.48

Chronic heavy alcohol use can cause acute pancreatitis (sudden inflammation and damage to the pancreas that resolves over several days)9,48 and chronic pancreatitis (inflammation of the pancreas that does not heal and worsens over time).48,49 Acute pancreatitis typically causes abdominal and back pain, nausea and fever49 and may occur a few hours or up to two days after drinking alcohol.48 In 20% to 30% of people, acute pancreatitis is a severe, life-threatening condition, which requires treatment in hospital.50

Chronic pancreatitis typically occurs in people aged 30 to 40-years-old and can cause abdominal pain, weight loss, diabetes, malnutrition and oily bowel motions (because the pancreas helps to digest fat and when the pancreas is damaged, fats are excreted out of the bowel instead of being absorbed into the body).48 The risk of acute and chronic pancreatitis increases with higher alcohol use.9

Moderate alcohol use is associated with a reduced risk of developing type 2 diabetes, although the exact reason for this is not certain.9

Immediate effects of alcohol use

Being drunk increases the chances of having unsafe sex (without a condom), having sex that is later regretted or experiencing sexual assault51,52 as alcohol impairs judgment and lowers inhibitions.4 Such sexual experiences are likely to also increase the risk of getting a sexually transmitted infection53 or having an unplanned pregnancy.

Long-term effects of alcohol use

Chronic heavy alcohol use can lead to impotence, loss of sex drive, wasting of the testicles and reduced fertility for men.35,54 This is primarily due to alcohol affecting testosterone levels.

For women it can lead to reduced fertility and can make periods heavy, irregular or stop altogether.19,35 Consuming alcohol while pregnant may increase the risk of miscarriage55,56, low birth weight13, stillbirth and premature birth.9,57 It can also cause significant abnormalities in the unborn, developing baby (Fetal Alcohol Spectrum Disorder - FASD).4,13,57,58

The evidence related to alcohol and fat is evolving. This section is a brief summary of the evidence available at the time of publication.

Immediate effects of alcohol use

Acute alcohol use can lead to skin flushing and worsen the appearance of skin conditions such as rosacea (a chronic facial skin rash).59

Long-term effects of alcohol use

Chronic heavy alcohol use, when associated with serious liver disease and liver failure, can also cause yellowing of the skin, decreased body hair and spider veins.40,60

Alcohol is a high-calorie beverage. One standard drink (100ml of wine, 30ml of spirits or 280ml of standard beer) contains 290kJ, close to half the energy of a can of fizzy drink. Alcohol is also an appetite stimulant and people tend to eat more when consuming alcohol with their meals.61 However, while theoretically the potential for alcohol to increase weight is clear, and some studies find that alcohol use is associated with increased weight62,63, others find the opposite result.64,65

Alcohol seems more likely to cause weight gain in those who drink intermittently (moderately to heavily), in those who are already overweight, in those eating a high-fat diet, and in men.63,66,67 For people concerned about their weight, nutritionists advise people to take into account how much energy alcohol is contributing to their diet.68

Chronic heavy drinkers are likely to be malnourished as alcohol has little nutritional value and replaces nutritious food in the diet.23

Immediate effects of alcohol use

Being drunk can lead to nausea and vomiting, diarrhoea, heartburn (when acid from the stomach rises up into the food pipe, due to alcohol causing the muscle around the outlet of the stomach to relax) and acute gastritis (inflammation of the lining of the stomach, which causes stomach pain, nausea, loss of appetite and indigestion).4,5,23,38 Vomiting and diarrhoea can result in dehydration, salt imbalances and the build-up of acids in the body, especially in combination with excessive alcohol intake.5 Inhaling vomit can lead to bronchitis or pneumonia (infection of the lungs). Vomit can block the airway and windpipe when blood alcohol is very high and breathing and consciousness are impaired.5

Persistent vomiting and retching after heavy use on a single occasion can sometimes (rarely) rip the food pipe (a Mallory Weiss tear), which leads to vomiting of blood.

Long-term effects of alcohol use

Long-term alcohol use can cause cancer of the food pipe (oesophagus) and drinking 50g of alcohol a day (five standard drinks) doubles the risk compared to a non-drinker.9,29,69 However, the risk is much increased in people who drink alcohol who are also deficient in a liver enzyme that metabolises alcohol (East Asian populations are commonly deficient in this enzyme).7,29 The risk is also increased in smokers.70 Chronic heavy alcohol use can also lead to chronic gastritis but it may protect against infection from Helicobacter pylori, the bacteria that cause ulcers of the stomach.16,38,71 In cases of advanced liver disease due to prolonged heavy alcohol use, the veins to the stomach and oesophagus can swell and may burst, causing life-threatening bleeding.