Alcohol and medicine use

Written by: Editors

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Drinking alcohol is a widely accepted social activity in Europe. From company functions to a relaxing evening at home, a significant proportion of adults drink alcohol on a regular basis. However, unlike other beverages, alcohol is a stimulant. It binds to receptors in the body and influences biological and chemical processes (and behaviours), both in the short and the long term. Mixing medications with alcohol can have unpredictable and unwanted consequences. You should always take this into account when taking prescription medicines, over-the-counter medicines or supplements.

Direct drug interactions

Drinking alcohol can interfere with how medicines work. In the short term, alcohol can increase the effects of medicines, which can lead to poisoning. Long-term alcohol consumption can also cause medicines to be less effective, because the speed with which they are broken down inside the body is affected.

For example, mixing alcohol with an oral anticoagulant called warfarin increases the risk of bleeding in the short term, while in the long term it increases the risk of thrombosis. With phenytoin, a medicine used to treat epilepsy, alcohol also increases the medicine’s short-term effects and decreases its long-term effects.

With some medicines, such as the antibiotic metronidazole and calcium blocker verapamil, it works the other way around: these medicines influence how alcohol is broken down in the body, intensifying the effect.

Indirect drug interactions

The most common effect of mixing alcohol and medication is that they amplify each other's effect: your body has to break down both substances. Alcohol affects mood and behaviour, and dulls the senses. It can cause dehydration, dizziness and blood pressure fluctuations. It also dilates your blood vessels, causing your heart to pump harder and faster to circulate blood throughout the body. Furthermore, alcohol irritates the stomach lining and makes your liver work very hard to get rid of toxins.

When you mix alcohol with medicines that have a similar effect, this can have several consequences. Below we have listed some of them.

Special drug interactions

Different antibiotics can interact with alcohol in different ways. Most antibiotics can be taken with alcohol, at least in moderation. However, with some antibiotics, like metronidazole, the combination can cause a severe reaction. Therefore, it’s best to avoid alcohol while taking metronidazole. Two other widely used antibiotics, doxycycline and erythromycin, become less effective with alcohol consumption.

Combining paracetamol (acetaminophen) with alcohol can severely damage your liver. Drinking alcohol while taking antidepressants can worsen depression and suicidal behaviour. So it's very important that you don't drink if you are taking paracetamol or antidepressants.

Herbal remedies containing St John’s Wort, kava and lavender are also known to interact with alcohol.

Vulnerable groups

Women and elderly people are more sensitive to the effects of alcohol. This is because women tend to be smaller. They also have less water in their bodies to help dilute the alcohol in their blood streams. Drinking alcohol can also lead to uninhibited sexual behaviour, which increases the risk of unsafe sex and pregnancy.

As people age, changes in the body make the elimination of alcohol less efficient and alcohol stays in their system longer. Elderly people have more health problems and often use more medications than younger people. They also have a higher risk of falls and fractures due to side effects.

The effects of drug interactions are usually unwanted, but not for people with long-term alcohol abuse problems: there are medicines whose side effects can help these people manage their addiction. If you think you may benefit from these medicines, ask your doctor for advice.

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