It’s long been known, but the details have also long been sketchy: the fact that grapefruit can interact with certain prescription drugs, leading either to negative side effects or to loss of the drug’s efficacy, or both. But studies that examine grapefruit have mostly been limited to trials of individual drugs, so exactly how widespread these drug interactions are has been, to some degree, shrouded in mystery.
Even many medical professionals were surprised when, late last month, a review was released that showed adverse reactions associated with more than 85 prescription drugs. Published in the Canadian Medical Association Journal, the review looked at 161 previously published studies, most of them clinical trials of drugs, that looked at grapefruit–drug interactions. As noted in an article at MedPage Today, common adverse reactions included heartbeat irregularities, bone marrow toxicity, gastrointestinal bleeding, urine retention, dizziness, low blood pressure, and kidney toxicity — not exactly minor side effects. The study found that as little as 200–250 milliliters, or 7–8 ounces, of grapefruit juice were all that was needed to trigger a reaction. (Other types of citrus fruits, including limes, Seville oranges — a common ingredient in marmalade — and pommelos also contain the same problem chemical as grapefruit.)
Several of the drugs named in the review are especially likely to be taken by people with diabetes, including two blood-glucose-lowering Type 2 diabetes drugs, repaglinide (brand name Prandin) and saxagliptin (Onglyza). Other commonly prescribed drugs include atorvastatin (Lipitor, generic options) and simvastatin (Zocor, generic options), both lipid-lowering drugs. Other drug categories with grapefruit interactions include anticancer, anti-inflammatory, immunosuppressant, and nervous-system drugs, including many prescription painkillers. A complete list of the drugs cited in the review can be found here.
How do you feel about grapefruit — did you, or do you now, consider it risky? Have you ever had an adverse reaction from grapefruit and a prescription drug? Have you ever been told by your doctor or pharmacist that you should avoid grapefruit because of a drug you’re taking? Is there a way to enjoy it in moderation, or should everyone who takes prescription drugs avoid it, just to be on the safe side? What about other citrus fruits, where the risk is certainly lower but may be present? Leave a comment below!