Taking These Medications With Grapefruit Can Be Dangerous!

Grapefruit can be part of a healthy diet because it contains nutrients that the body needs, such as potassium and vitamin C.

However, this fruit — consumed whole or as a freshly squeezed juice or juice from concentrate — can interact with numerous oral medications, potentially leading to serious — sometimes deadly — adverse effects.[1] These medications treat a wide spectrum of conditions, including allergies, abnormal heart rhythms, high blood pressure and psychiatric disorders.

Older adults are prime consumers of grapefruit and commonly are taking many prescription drugs. Therefore, they have the greatest risk of experiencing drug-grapefruit interactions and are the most vulnerable to the adverse effects of these interactions.[2] Learn about the various drugs that interact with this fruit to protect yourself and your loved ones.

Interactions leading to drug overdoses

Grapefruit interacts with certain oral medications in two different ways. First and most commonly, substances in the fruit interfere with an enzyme in the intestines and liver that is responsible for metabolizing (breaking down) certain drugs.[3] This interference, which can last for more than three days following ingestion of grapefruit,[4] results in an increased amount of the drug being absorbed into the bloodstream, leading to a higher drug concentration in the body.

The table below lists some of the more than 80 medications that have been ranked as having "moderate-to-very-high" risk of having this type of interaction with grapefruit, according to a group of Canadian researchers.[5] These researchers discovered this drug-grapefruit interaction more than 25 years ago.

The consequences of this kind of interaction can range from no symptoms in some cases to life-threatening toxicity in other cases.[6] For example, grapefruit can cause marked increases in the blood levels of certain cholesterol-lowering drugs, such as atorvastatin (LIPITOR) and simvastatin (FLOLIPID, VYTORIN, ZOCOR), which can result in rhabdomyolysis (severe muscle breakdown) and kidney failure.[7] Similarly, grapefruit causes high blood levels of some high blood pressure medications such as felodipine (generic only), which can lead to dangerously low blood pressure, light-headedness and loss of consciousness.

Interactions leading to low drug levels

The second, less common way in which grapefruit can interact with oral drugs is by blocking a substance that is involved in the absorption of some drugs from the intestines.[8] This interference, which can last for a few hours, decreases the amount of these drugs in the body and may prevent these drugs from having the desired effect.[9]

Drugs that interact with grapefruit in this manner include the allergy drug fexofenadine (ALLEGRA), the antibiotic ciprofloxacin (CIPRO) and the high blood pressure drug aliskiren (TEKTURNA).[10] Notably, Public Citizen's Health Research Group designates these three drugs as Limited Use.

Examples of Oral Drugs for Which the Interaction with Grapefruit Can Lead to Drug Overdoses[11]†

†Combination drugs that contain other active ingredients were excluded from the table.
*Designated as Limited Use
**Designated as Do Not Use

What You Can Do

Many drugs, including others not mentioned in this article, may adversely interact with grapefruit. Therefore, if you consume any amount of grapefruit or grapefruit products, ask your doctor or pharmacist whether any of your oral medications interact adversely with grapefruit. You also may be able to find such information by searching the "Patient Information" section at the end of the labeling of your medications on DailyMed (dailymed.nlm.nih.gov).

Depending on the drug, the interaction with grapefruit can last from four hours to more than three days.[12] Therefore, consult your doctor regarding how long you should refrain from consuming grapefruit if a drug you are taking interacts with this fruit. Alternatively, your doctor may switch you to another medication that does not interact with grapefruit.

Note that Seville oranges, which often are used to make orange marmalade, and tangelos affect the same enzyme in the intestines and liver as grapefruit juice. Therefore, discuss with your doctor whether you should avoid these fruits as well when you are taking a medication that interacts with grapefruit. Do not stop taking any prescription drug without first talking to your doctor.
 

References

[1] Bailey DG, Dresser G, Arnold JM. Grapefruit-medication interactions: Forbidden fruit or avoidable consequences? CMAJ. 2013;185(4):309-316.

[2] Ibid.

[3] Ibid.

[4] Pirmohamed M. Drug-grapefruit juice interactions: Two mechanisms are clear but individual responses vary. BMJ. 2013;346(January 7):f1. doi:10.1136/bmj.f1.

[5] Bailey DG, Dresser G, Arnold JM. Grapefruit-medication interactions: Forbidden fruit or avoidable consequences? CMAJ. 2013;185(4):309-316.

[6] Pirmohamed M. Drug-grapefruit juice interactions: Two mechanisms are clear but individual responses vary. BMJ. 2013;346(January 7):f1. doi:10.1136/bmj.f1.

[7] Bailey DG, Dresser G, Arnold JM. Grapefruit-medication interactions: Forbidden fruit or avoidable consequences? CMAJ. 2013;185(4):309-316.

[8] Pirmohamed M. Drug-grapefruit juice interactions: Two mechanisms are clear but individual responses vary. BMJ. 2013;346(January 7):f1. doi:10.1136/bmj.f1.

[9] Ibid.

[10] Ibid.

[11] Bailey DG, Dresser G, Arnold JM. Grapefruit-medication interactions: Forbidden fruit or avoidable consequences? CMAJ. 2013;185(4):309-316.

[12] Pirmohamed M. Drug-grapefruit juice interactions: Two mechanisms are clear but individual responses vary. BMJ. 2013;346(January 7):f1. doi:10.1136/bmj.f1.