Certain medications for depression, high blood pressure, cholesterol and Crohn's disease could be impacted by the consumption of grapefruit or its juice.

Despite being a good source of vitamin C, grapefruit can interfere with an essential enzyme that helps break down medications in the body.

This interference could lead to an excessive amount of the drug entering your bloodstream, potentially causing heightened or additional side effects.

The British Liver Trust has issued a warning: "When you have too much of the medicine in your body you are at risk of severe side effects. These could be very dangerous."

On the other hand, grapefruit can also inhibit some transporters responsible for moving medications into the body's cells where they perform their function, decreasing how effective these pills are. 

Furthermore, individual levels of the enzyme vary, meaning reactions to the same grapefruit and medication combination can differ from person to person.

The NHS specifically cautions those on two types of medication - statins, typically used for cholesterol, and sertraline, an antidepressant: "Grapefruit juice can affect some statins and increase your risk of side effects. A doctor may advise you to avoid it completely or only consume small quantities."

When it comes to sertraline, the guidelines are straightforward: "Do not drink grapefruit juice while you're taking this medicine. Grapefruit juice can increase the amount of sertraline in your body and increase the risk of side effects."

Grapefruit juice can be especially troublesome for certain medications, such as statins, where excessive consumption can lead to an overload of the drug in your system. This can put undue strain on your liver and kidneys, potentially increasing the risk of muscle damage or organ failure, warn experts at News Medical.

Regrettably, there's no 'safe window' for consuming grapefruit or its juice before or after taking your medication. As explained by the British Liver Trust: "The effect of grapefruit on the enzyme can last more than 24 hours. So even if you only take your medicine once a day it is not safe to have grapefruit at the other end of the day."

The FDA in America has an extended list of warnings about medications that could be affected by grapefruit juice.

This includes some prescribed drugs used to treat high blood pressure, organ-transplant rejection, anxiety, Crohn's disease and even certain antihistamines for allergies. In the case of fexofenadine, better known as the allergy medication Allegra, grapefruit juice could reduce its effectiveness.

The FDA also noted that this medication interacts negatively with orange and apple juice.