Doctor issues urgent fruit warning for people taking common medications

The suspicious snack

Dr Nicole James, a former UK resident doctor now based in Illinois, has warned about the potential risks of consuming grapefruit while taking certain medications.

She highlighted common drugs such as sertraline and midazolam as examples of medicines that could be affected.

Although she acknowledged that grapefruit can be a healthy and enjoyable snack, she explained that it contains natural compounds that can affect the way the body processes some medicines.

The fruit contains compounds including furanocoumarins and flavonoids, which can block an important enzyme called cytochrome P450 3A4 (CYP3A4). 

This enzyme plays a key role in breaking down many oral medications so they can be processed properly by the body.

When grapefruit blocks CYP3A4, medicines are not broken down as they normally would be before entering the bloodstream. 

This can lead to unusually high levels of medication in the body, potentially increasing the risk of serious and dangerous side effects.

“Patients taking statins could experience higher levels than normal which can cause muscle break down and cramps,” Dr James says.

She also warned that it does not take a large amount of grapefruit to trigger this interaction. 

Just one grapefruit or around 200ml of grapefruit juice can cause a clinically significant increase in medication levels, with the effects lasting for up to 72 hours.

For this reason, Dr James advised people to be cautious with mixed fruit juices, smoothies and cocktails this summer, as grapefruit juice is often used as an ingredient in these drinks.