Here’s how a healthy fruit juice could actually kill you – and when to see a doctor

DRINKING grapefruit juice could kill you, a growing body of research suggests.

Dozens of drugs are known or thought to interact with the beverage, causing serious and sometimes life-threatening side effects.

Studies have shown it’s because grapefruit is high in furanocoumarins.

These chemical compounds can reduce or enhance certain prescription and over-the-counter medications, which can be fatal in some people.

Pharmacologist Shiew Mei Huang, of the US Food and Drug Administration (FDA), said: “The juice lets more of the drug enter the blood.

“When there is too much drug in the blood, you may have more side effects.”

The NHS lists the following medications as potentially being affected by grapefruit:

• Cholesterol-lowering drugs (statins such as simvastatin and atorvastatin)
• Blood pressure and heart disease meds (calcium channel blockers such as amlodipine, felodipine, lacidipine, lercanidipine, nicardipine, nifedipine, nimodipine, verapamil)
• Blood clot prevention medicine (anticoagulants such as warfarin)
• Antiplatelets (such as clopidogrel, ticagrelor)
• Immunosuppressants (such as ciclosporin, sirolimus and tacrolimus)
• Crohn’s disease meds (such as budesonide)
• Cytotoxic cancer treatments

The FDA also has these drugs on its list:

• Anti-anxiety medicine (such as buspirone)
• Drugs to treat abnormal heart rhythms (such as amiodarone)
• Antihistamines (such as fexofenadine)

But these lists are not exhaustive, and people should speak to a specialist before consuming grapefruit when taking medication.

Scientists say furanocoumarins interfere with the way the body produces Cytochrome P450 3A4 (or CYP3A4), mainly in the liver and small intestine.

This enzyme helps to break down drugs, and a single glass of grapefruit juice could be enough to impact its ability.

Researchers in the 1990s found that just 240ml of the stuff increased a tablet’s concentration three-fold when compared with water.

A separate study discovered a glass of grapefruit juice taken alongside cholesterol meds increased statin levels in the blood by 260 per cent.

Essentially, the juice means more of the medication enters your bloodstream, and stays in your body for longer, triggering an overdose – with the effects lasting up to three days.

For some meds, this won’t make much difference.

But for others, it can spark an increased heart rate, shortness of breath, internal bleeding, bone marrow toxicity, muscle tissue wastage and kidney failure, a study published in the Canadian Medical Association Journal suggests.

‘THERAPEUTIC TO TOXIC’

In rare cases, this can be fatal, scientists in Utah found in 2010.

David Bailey, a clinical pharmacologist who has studied the topic in detail, previously said: “Taking one tablet with a glass of grapefruit juice is like taking 20 tablets with a glass of water.

“This is unintentional overdosing. So it’s not surprising that these levels go from what we call therapeutic to toxic.”

The reverse is also possible. Grapefruit can reduce the effectiveness of certain medicines, which is also dangerous.

This is because it impacts proteins in the body known as drug transporters, which help move a medicine into our cells for absorption.

Fexofenadine, used to treat allergy symptoms, is one of the medicines affected, according to the FDA.

Shiew Mei Huang said: “Grapefruit juice can cause less fexofenadine to enter the blood”, decreasing how well it works.

“Do not take it with fruit juices.”

Furanocoumarins are also found in Seville oranges, pomelos and tangelos, but these fruits have not been studied in as much detail as grapefruit.

If you have questions about whether you can safely consume grapefruit juice, contact your pharmacist or GP.

If you think you or someone you know might have overdosed, call 999 or visit your nearest A&E.