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Grapefruit and Medication
For many, grapefruit is a tasty, refreshing, low-calorie fruit to start the day with. However, grapefruit and medication don’t pair well.
Eating grapefruit or drinking grapefruit juice can affect several prescription medications. In some cases, it has been linked to overdoses of some drugs because it prevents them from being effectively broken down in the liver and intestines.
Research Institute in Canada
The fruit can cause overdoses of some drugs by stopping the medicines from being broken down in the intestines and the liver.
Researchers at the Lawson Health Research Institute in Canada, who first identified the risk, said the number of drugs that became dangerous with grapefruit was increasing rapidly. It is thought that as many as 85 medications could interact adversely with grapefruit, although many of those are not prescribed in the UK.
Range of Conditions
They include some drugs for a range of conditions, external including blood pressure, cancer and cholesterol-lowering statins and those taken to suppress the immune system after an organ transplant.
Chemicals in grapefruit, furanocoumarins, wipe out an enzyme which breaks the drugs down. It means much more of the drug escapes the digestive system than the body can handle.
Toxic
Three times the levels, external of one blood pressure drug, felodipine, was reported after patients had a glass of grapefruit juice compared with a glass of water.
The side effects are varied depending on the drug, but include stomach bleeds, altered heart beat, kidney damage and sudden death.
Dr David Bailey, one of the researchers, told the BBC: “One tablet with a glass of grapefruit juice can be like taking five or 10 tablets with a glass of water and people say I don’t believe it, but I can show you that scientifically it is sound.
“So you can unintentionally go from a therapeutic level to a toxic level just by consuming grapefruit juice.”
The report said: “We contend that there remains a lack of knowledge about this interaction in the general health care community.”
They added: “Unless health care professionals are aware of the possibility that the adverse event they are seeing might have an origin in the recent addition of grapefruit to the patient’s diet, it is very unlikely that they will investigate it.”
Other citrus fruits such as Seville oranges, often used in marmalade, and limes have the same effect.
Neal Patel, from the Royal Pharmaceutical Society said: “Grapefruit isn’t the only food that can cause issues, for example milk can stop the absorption of some antibiotics if taken at the same time.
“Although some of these interactions may not be clinically significant, some may lead to more serious outcomes.
“Pharmacists are the best port of call for anyone concerned about how their diet may affect their medication. Information about any interactions would always be included in the patient information leaflet that comes with the medicine.”
Which medications are at increased risk ?
- Cholesterol lowering statins
- Antibiotics
- Certain blood thinning bloods
- Calcium channel blockers (used to treat high blood pressure)
In addition, grapefruit has potassium, which has been shown to decrease high blood pressure. One grapefruit has about 300 milligrams of potassium. A study that reviewed 22 other studies noted that blood pressure was reduced with higher potassium intake.
Many pharmacists will alert you to the fact you shouldn’t eat grapefruit and the printed information included with the medication should also state this.
