Grapefruit Could Affect Medications


Recent studies show that the "wonder fruit" may not be the cure-all it has been purported to be.

Long before the coining of the phrase “superfruit,” and acai and mangosteen became staples in the health “nut’s” vocabulary, the humble grapefruit was a go-to fruit on many levels. 

Besides being a reliable source of vitamin C, and a godsend for cold sufferers, it is also packed with such vitamins as potassium, lycopene, calcium and phosphorus. 

With its high fiber and low calorie content, whole grapefruit became a miracle food for dieters, boosting metabolism, lowering insulin levels and suppressing the appetite. 

However, recent studies have shown that the fruit may not be the cure-all it has been purported to be; indeed, concern over what could be dangerous interactions with certain medications has heightened questions over whether the fruit should be consumed by those on a variety of pills and tablets.

Trouble in superfood paradise was first discovered in 1989 when the reports about its interference with medication absorption were released to the general public. In 1991, the Lancet medical journal reported that the effects of medications Felodipine and Nifedipine were compromised as a result of grapefruit interaction. 

Furthermore, a study published in the July 2007 edition of the British Journal of Cancer reported that eating grapefruit every day could raise the risk of developing breast cancer by almost a third.

The latest storm of controversy took place at the end of 2012, when The New York Times reported a case where a wom­­­an nearly died as grapefruit juice amplified the ­effects of Verapamil, a blood pressure drug she took to remedy her headaches.

Mark Chaballa, clinical phar­macist of Thomas Jefferson University Hospital, suggests patients keep calm and consult  with medical professionals they trust.

“I work mainly with transplant patients, so we have known about various grapefruit-related drug interactions for 20 years,” Chaballa says. 

Why, after five years, is grape­­fruit making such news again? “There are always new drugs coming into the market,” he explains.

Grapefruit is not alone: “There are hundreds of studies about different drugs reacting with different foods. It is important for patients to be proactive in understanding how drugs they take metabolize.”

Chaballa says news reports like the most recent in the Times can be helpful, especially if it prompts more patients to start conversations with their doctors and pharmacists. However, there may be a point where too much information, including conflicting facts, can create problems.

“From the scientific perspective, there is a lot of confusion,” Chaballa observes. 

Though it was once believed that flavenoids triggered the chemical reactions that compromise or overcharge a medication’s functions, chemical reactions are now often traced to furanocoumarins, an enzyme unique to the grapefruit. 

Nicole Dean, a registered dietician and clinical nutrition specialist at Temple University Hospital, explains that this chem­ical attaches to the enzymes in the intestines that normally help break down the medications we take. When it interferes with digestion of the medicine, the drug stays in the system longer, and the potency can be magnified.

“Having certain medications stay too long in your system can be problematic and potentially dangerous in situations where you are driving or operating heavy machinery,” says Dean. With prescriptions such as “anti-seizure medications, people need a specific amount to keep them stable, but when the grape­fruit enzyme interacts with that, it will create the effect of an overdose.”

Dean reassures citrus lovers that they have many other alternatives, including oranges, lem­ons and limes. Personal nutrition coach Joanna Chodorowska of Philadelphia-based Nutrition in Motion, meanwhile, cautions that grapefruit juice more than the whole fruit will exacerbate certain problems. And, even after you have made sure the medication is not on the list of 85 “at risk” drugs, she says the only way to get the fruit’s fullest benefits is by consuming it fresh and whole.

Conversely, in a study published last August in Clinical Cancer Research, and supported by the National Institutes of Health, it was found that eight ounces a day of grapefruit juice could slow the body’s metabolism of a drug called sirolimus, which has been approved for transplant patients but may also help many people with cancer.

For a list of medications that interact with grapefruit, go to:, and enter grapefruit medications.


Please enter your comment!
Please enter your name here