Medicines and merriment: how to prevent medicines interactions

Published in Medicinewise Living

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Mixing certain foods or drinks with medicines can change how a medicine works in your body.
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Mixing certain foods or drink (including alcohol) with medicines can change how a medicine works in your body. This is called an interaction. As well as changing how well a medicine works, these interactions can cause unwanted side effects.


Some medicines need to be taken on an empty stomach so you get the full effect of the active ingredient(s). The active ingredient is the chemical in the medicine that makes it work.

Other medicines may need to be taken with food to help lessen side effects like an upset stomach. Some foods, like dairy products and grapefruit (including grapefruit juice), may also interfere with how well your medicine works, or increase the chance of side effects.

You won't always need to avoid these foods completely, it may just be a matter of not taking them at the same time (e.g. separating that particular food and the medicine by a few hours).

Always check with your doctor or pharmacist about taking medicines with food. You can also find instructions on the medicine label or packaging, and in the consumer medicine information (CMI) for your medicine (look in the 'How to take it' section).


Because alcohol can stay in the body for several hours, interactions may occur even if you take your medicine some time after your last drink. Some people are also more susceptible to the effects of alcohol because of their size, gender or current health.

Interactions between some medicines (for example, the antibiotics metronidazole and tinidazole) and alcohol can produce severe reactions like nausea, vomiting and skin flushing.

Some medicines can increase the effects of alcohol, like drowsiness, sleepiness, dizziness, and difficulty concentrating. This can happen with medicines used for sleep problems and anxiety, antidepressants, cough and cold medicines, and allergy and travel sickness medicines.

Whether you are taking prescription, over-the-counter or complementary medicines it is important to check with your doctor or pharmacist before drinking alcohol. This will help you to minimise the chance of potentially harmful interactions. In most cases you will not have to completely avoid alcohol, but you may need to limit your intake.  

The medicines mentioned are not an exhaustive list and you should seek advice from your doctor or pharmacist about your specific circumstances.

Medicines and merriment 

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