6 surprising foods and drinks that could affect your medication

When you're prescribed a new medication, you may think you can simply take it without having to think about your diet. But depending on what you've been advised to take, this could be a major mistake. 

Here we take a look at some of the things that can impact common prescription medications, from the relatively well known to the unexpected. 

It's not an exhaustive list, so you should always read the patient information leaflet that comes with any new meds or seek advice from your pharmacist. 

Professor Claire Anderson, president of the Royal Pharmaceutical Society, says: 'Pharmacists are experts in medicines and can offer tailored advice to ensure you’re taking your medicines safely and effectively.'

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1. Grapefruit juice

Grapefruit is known to interact with a number of common medications. Chemicals found in grapefruit juice can block enzymes in the body responsible for breaking down medications.

This means medication stays in the body for longer and can lead to much higher (and potentially toxic) doses than expected, although in some cases it can also hinder drugs from entering your system, reducing their effectiveness.

Common meds grapefruit interacts with: statins, calcium channel blockers, immunosuppressants, cytoxic medicines, anticoagulants, antihistamines, sleeping pills (including benzodiazepines) - and more.

2. Liquorice

Liquorice might not be to everyone's taste, but if you're partial, double-check that it won't do more harm than good: excessive amounts can impact blood pressure and potassium levels, among other things.

Be aware that liquorice can crop up in unexpected places, including some herbal tea blends and other drinks, so it's worth checking the ingredients, even if it's not listed on the front of the packaging.

Common meds liquorice interacts with: blood pressure medicine, diuretics, hormone therapy drugs, blood thinners and more

3. Herbal supplements

Herbal supplements are generally classed as food supplements unless they make specific health claims, so they aren't required to come with extensive information leaflets. But, while they may be food or nature-based, that doesn't mean they're benign.

Some can impact the way your medication works, especially if in higher doses than what you'd typically eat.

Some supplements, such as St John's wort and ginkgo biloba, are known to interact with some medications and typically carry a warning, but others may not be specific, so it's always best to ask your GP or prescriber if you're taking any supplements, to ensure the combination is safe.

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4. Alcohol

Alcohol is one of the more obvious interactants on this list. Drinking to excess is bad for your health regardless of whether you're on medication, but people on certain medications should take special care. 

With some medications, you're advised to avoid alcohol altogether, while with others you should just limit your consumption. 

If you're taking statins, for example, you shouldn't drink more than 14 units of alcohol a week. 

Avoid if you're taking: antidepressants, certain sedatives, some antihistamines and more

5. Strong cheese

If you're taking MAOIs – a less commonly prescribed type of antidepressant that can also be used for neurological disorders and stroke – there's a chance your favourite stinky cheese could have serious side effects. 

MAOIs stop your body from breaking down a chemical called tyramine, which these cheeses include, so eating them could lead to a sudden and potentially dangerous rise in blood pressure from increased tyramine levels – the so-called 'cheese effect'. 

Avoid if you're taking: MAOI antidepressants

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6. Herbal teas

Depending on the blend, sipping too much of certain types of herbal tea could also impact the effectiveness of your medication. 

We've already mentioned that liquorice, found in some herbal teas, could affect your medication. The same is true of some other herbal blends. 

Popular herbal teas like green tea and ginseng have been found to affect some drugs in clinical studies. 

Avoid green tea if you're taking: certain cardiovascular drugs

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