How grapefruit juice can cause adverse reactions to medications
Drug-food interactions, which can happen with over-the-counter or prescription drugs, can change how a medication is absorbed and completely change its intended result. Adverse drug reactions can cause very serious side effects and even death.
Emma Hammett is an experienced nurse and first aid trainer, and is also the founder of First Aid For Life. In an article for The Hippocratic Post, she explains how grapefruit can react dangerously with some medications by intensifying their effect.
“Grapefruit can seriously affect the way your medicines work, especially if you are taking some of these common medicines for high blood pressure, cardiac arrhythmia, a statin to reduce your cholesterol, or fexofenadine for allergies such as hay fever,” writes Hammett.
She says that the extent of the interaction will vary depending on the person, and some individuals will not experience any adverse effects at all.
The presence of grapefruit juice most commonly results in too much medication entering the bloodstream and then remaining in the body for a long period of time.
Hammett explains: “Many drugs are metabolised (broken down) with the help of a vital enzyme called cytochrome P450 3A4 (CYP3A4) in the small intestine. The furanocoumarins within grapefruit frequently block the action of CYP3A4. Instead of being metabolised, more of the drug enters the blood and stays in the body longer.”
According to Hammett, it does not take much grapefruit juice to boost the levels of certain drugs.
“A single glass of juice can reduce the production of the intestinal enzyme that regulates absorption by up to 47%. The furanocoumarins take a while to be removed from your system and so a third of their impact is still evident after 24 hours.”
The grapefruit juice could continue to interact with medications while it persists in the body.
“Grapefruit is a healthy option, packed full of Vitamin C. So before banishing your beloved grapefruit from the breakfast table, find out if there are any contraindications to drinking grapefruit juice while taking your medication,” writes Hammett. “Your doctor, pharmacist or healthcare provider should be able to advise.”