Grapefruit and medications: what it actually affects

Grapefruit sharply raises blood levels of these two statins — enough that the simvastatin FDA label names grapefruit juice specifically and tells patients to avoid large quantities. High statin levels raise the risk of muscle injury (myopathy) and, rarely, the serious muscle breakdown called rhabdomyolysis.

What to do: Avoid grapefruit and grapefruit juice on simvastatin or lovastatin. If you love grapefruit, ask your prescriber about a statin it does NOT affect — pravastatin, rosuvastatin and fluvastatin are cleared differently and are the usual grapefruit-safe choices.

A smaller effect than simvastatin, but grapefruit still raises atorvastatin levels somewhat. Everyday amounts are usually tolerated; large daily quantities of juice are where it matters.

What to do: Occasional grapefruit is generally fine; avoid large daily amounts. When in doubt, ask your pharmacist.

Grapefruit markedly increases levels of several dihydropyridine calcium channel blockers — felodipine is the classic, textbook example — which can drop blood pressure too far and cause flushing, headache, dizziness or a fast heartbeat.

What to do: Avoid grapefruit with felodipine, nifedipine and nisoldipine. Amlodipine is much less affected and is the usual grapefruit-tolerant choice in this class — confirm with your prescriber.

Grapefruit raises levels of these narrow-margin immunosuppressants, and the tacrolimus label warns against it. Too-high levels are toxic to the kidneys and nervous system; the swings also make the dose hard to control.

What to do: Avoid grapefruit entirely. Transplant medicines are dosed to a target blood level, and grapefruit sabotages that.

Grapefruit substantially increases buspirone levels, which can worsen its side effects — drowsiness, light-headedness and nausea.

What to do: Avoid grapefruit, or separate it well from the dose, on buspirone; ask your pharmacist about your specific dose.

Grapefruit raises levels of a few benzodiazepines cleared by CYP3A4, deepening and prolonging their sedation. Most benzodiazepines are NOT affected — this is specific to a couple of them.

What to do: Avoid grapefruit around oral triazolam or midazolam. If you take a different benzodiazepine, check it rather than assume — most are unaffected.

Grapefruit raises amiodarone levels; the drug already has a narrow margin and serious effects on the heart, lungs and thyroid, so added exposure is unwelcome.

What to do: Avoid grapefruit on amiodarone or dronedarone.