Grapefruit and Prescription Drugs: A Potentially Dangerous Combination

Pharmacists have known of the potential dangerous interaction grapefruit and grapefruit juice have with certain prescription drugs for at least 20 years. However, a new Canadian study published this week in the Canadian Medical Association Journal finds the number of commonly used prescription drugs with this possible dangerous interaction with grapefruit is on the rise. The potential side effects are escalating as well, according to researchers, and can include death. 

Each year, researchers say, more than six new drugs that hit the market also land on the “Grapefruit Interacting Drugs” list, bringing the total now identified to more than 85 drugs. Though some side effects are mild, others include acute kidney failure, respiratory failure, gastric bleeding and sudden death. When researchers first discovered this connection, they found ill effects were due to the fruit causing certain prescription drugs to concentrate in the patient’s bloodstream.

Whether eaten or consumed as a drink, citrus – including grapefruit, limes, pomelos, and some oranges – contain an active ingredient that interacts with the digestive enzyme CYP3A4. This enzyme’s job is to protect the body from harmful toxins, which means it typically dilutes the effectiveness of medication by about 50 percent. Physicians take this into account when prescribing medication to their patients.

However, citrus like grapefruit can interrupt this normal process, thus increasing the strength of the medication dramatically. Taken with the wrong medications, grapefruit can triple or quadruple the dosage the patient thinks they are receiving once it is in their system.

Lovelace pharmacists advise patients to stay informed. “Grapefruit can cause the inhibition of the breakdown of some common blood pressure and cholesterol-lowering medications amongst others,” says Lovelace Pharmacy Manager Andrew Kurtz. “However, every year new drugs are being formulated and only a small percentage of those actually interact with grapefruit.”

To view the complete Grapefruit Interacting Drugs list that is put out by the Canadian Medical Association, click here.

If you have questions about the medications you take and their potential interaction with grapefruit and other citrus, Kurtz says, “the most important thing for patients to remember is that communication with your health care provider is key to preventing harmful drug-drug and drug-food interactions. Pharmacists and other health care providers can look at a patient’s medication list and determine if any of their medications do have an interaction with grapefruit. Communication with a licensed health care provider is the best way to prevent interactions and ensure safe medication therapy when considering adding grapefruit to their diet.” 

News and Events