Grapefruit: The Great Medication Meddler



I recently shared a post on my instagram about the interference risk between grapefruit and certain medications. But let's take a closer look at how it works, which medications are effected and other ways to boost your vitamin C intake.

Grapefruit and grapefruit juice has two ways in particular it can interfere with medications, the first is:

Increased levels of the drug

  1. Many medications are metabolised by the intestinal enzyme CYP3A4. However, grapefruit contains compounds known as furanocoumarins which can block the action of the CYP3A4 enzyme. This means it’s easier for the drug to pass from your gut to your blood steam, causing blood levels of the drug to rise faster and higher, increasing the risk of new or worsened side effects.

The second way grapefruit can interfere with medication is:

Lowered levels of the drug

  1. Some drugs are moved into the cells via transporters. Grapefruit can block this action, causing not enough of the drug to be moved into the cell and absorbed. Causing potential issues the medication not doing the job it was prescribed for.

It’s also interesting to note that we each have differing levels of the CYP3A4 enzyme, meaning we may all experience the grapefruit effect at various levels.

The take-away from both of these interferences is that you are not absorbing the amount of drug you are prescribed to be taking!

So, all of that being said, which medications does it mess with?


Drugs that interact with grapefruit and juice.
Grapefruit medication interactions list

This chart is not exhaustive and you should always discuss interaction risks with your doctor about any new or existing medications.

Can I just wait an hour after taking my medication to eat grapefruit?

Sadly, no! A MYTH is that you can wait an hour or two after taking your medication before consuming grapefruit and it will have no effect, however studies show grapefruit has a powerful effect that can last 1-3 days, so best to avoid for the entirety of the prescribed treatment time.

Does this mean grapefruit is 'bad'?

Not at all! This is not to villainise the humble grapefruit, it has many nutritious benefits such as vitamin C, potassium, dietary fibre, and other nutrients. Some swaps you can make could be bell peppers, strawberries, tomatoes and cruciferous veg.


Is it just grapefruit?

It’s important to note that although most other fruits and their juices are perfectly safe to consume with most medications, there are a few exceptions to be mindful of. Sevilla oranges may post similar risks as grapefruit, orange or apple juice can interact with fexofenadine and aliskerin. And pomegranate juice can interfere with some breast cancer medications.


What can I do about it?

Use this post as your reminder to always ask questions about the medication you're taking!

Ask more questions to stay informed on any interaction risks, your healthcare provider has a duty of care to discuss this with you. Fortunately, not all medications in any one drug class have a grapefruit interaction, so usually your doctor can find an alternative.


If you have any health questions you want answers to, send me a DM on instagram or facebook, or schedule a free discovery call via my website.


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