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Alcohol and the Human Body

alcohool and the human body


Alcohol has both immediate and long-term effects on your body. Learn about how alcohol affects your behaviour and your body.

Drinking alcohol has consequences that affect your body.

Before it reaches the liver, alcohol in the blood affects other vital organs. The most immediate effects can be seen in the brain.

How you feel depends on your mood at the time. If you are sad or angry before you drink, alcohol may initially put you in a better mood. But then the opposite occurs and you may end up even more sad or angry than before you started drinking.

Why does alcohol change behaviour?

As your body processes alcohol and your blood alcohol content rises, it can change how you feel—even if you don’t realize it.

Numbing effects
Your brain’s motor and sensory centers are affected by increasing blood-alcohol levels. You begin to have difficulty with co-ordination and fine motor functions, and your reaction time slows. The effects can be minor or major, depending on how much you drink.

Did you know?
If you have a blood-alcohol level of .08 – the legal limit for driving a motor vehicle in Canada – your reaction time will be 30-50 per cent slower than when you have no alcohol in your blood. In B.C., drivers with a blood alcohol content of .05 can be served with an immediate roadside prohibition and there is zero tolerance for novice drivers.

As you become intoxicated, your thinking and speaking skills are lowered. Since these skills normally allow you to resolve conflicts, there is a greater risk of aggressive and violent behaviour.

Excessive alcohol consumption can cause vomiting because of the way it affects your brain and the toxic acetaldehyde circulating in your blood.

Alcohol affects the kidneys’ ability to reabsorb enough water from your urine and your body ends up eliminating more water than it absorbs. The symptoms of dehydration are fatigue, back and neck pain, and headaches.

The immediate effects on the brain are not as noticeable among people who drink regularly because they’ve developed a strong tolerance for alcohol. As a result, they can often drink a great deal without feeling as many short-term effects. Such tolerance is both metabolic – the liver processes the alcohol more quickly and efficiently – and functional – the person learns to compensate for the deficits caused by alcohol.

But drinking regularly above the low-risk drinking guidelines has harmful effects that will be seen and felt in the long-term.

Want to learn more? Take the Alcohol Reality Check

How does alcohol affect other vital organs?

Heart and cardiovascular system
Just one or two drinks can affect your heart rate, blood pressure, circulation and contractions of the heart muscle, including its ability to pump blood through your body. These reactions can be serious if you already suffer from cardiovascular problems.

Among other things, alcohol causes small blood vessels beneath the skin to dilate, which increases blood circulation. The dilation of blood vessels also causes heat loss and a drop in body temperature.

The pancreas produces insulin, which the body needs to control blood sugar levels. Drinking alcohol causes a sudden spike in blood sugar, and the pancreas responds by producing more insulin. This causes a rapid drop in blood sugar and the symptoms of hypoglycaemia – dizziness, headaches, difficulty concentrating, depression, anxiety, trembling, cold sweats, heart palpitations, loss of co-ordination and stomach aches.

© Adapted from Éduc’alcool’s “Alcohol and Health” series, 2014. Used under license.
Last Updated: January 12, 2017