Short answer
A single glass of grapefruit juice can raise blood levels of certain medications 2–5 times and hold them there for up to 72 hours. At risk: statins, calcium channel blockers, post-transplant immunosuppressants, several targeted oncology drugs, and some antiarrhythmics and psychotropics. Safe citrus alternatives are sweet orange, mandarin, lemon, lime. Pomelo and Seville (bitter) orange behave like grapefruit.
What happens in the gut
Grapefruit pulp and juice contain furanocoumarins – primarily bergamottin and 6′,7′-dihydroxybergamottin. These molecules irreversibly inactivate the CYP3A4 isoform in the small intestinal wall. CYP3A4 is the enzyme responsible for first-pass metabolism of most lipophilic oral drugs.
The interaction logic:
- The drug is taken orally.
- Intestinal CYP3A4 normally clears 50–90% of the dose before it reaches systemic circulation.
- With the enzyme blocked by grapefruit, the full dose enters the bloodstream.
- Plasma levels rise several-fold, along with dose-dependent adverse effects.
The effect lasts 24–72 hours. New CYP3A4 molecules in enterocytes have to be synthesized de novo; until then, plasma drug levels do not normalize. So the rule «juice in the morning, pill at night» does not work.
The foundational reference is Bailey DG et al., CMAJ 2013 – a systematic review of 85 drugs with clinically meaningful grapefruit interaction, 43 of which can cause serious harm.
Drugs that should not be combined with grapefruit
Statins
| Drug | Risk | Substitute |
|---|---|---|
| Simvastatin | High: rhabdomyolysis, acute kidney injury | Rosuvastatin, pravastatin |
| Lovastatin | High | Rosuvastatin, pravastatin |
| Atorvastatin | Moderate, dose-dependent | Rosuvastatin if needed |
| Rosuvastatin, pravastatin, fluvastatin, pitavastatin | No interaction | – |
Source: FDA Consumer Update «Grapefruit Juice and Some Drugs Don’t Mix» (last revised 2021); AHA/ACC 2018 Guideline on the Management of Blood Cholesterol.
More on the molecule: atorvastatin.
Calcium channel blockers (hypertension, angina)
| Drug | Risk |
|---|---|
| Felodipine | High: AUC rises 2–3 fold, hypotension, tachycardia |
| Nisoldipine, nicardipine | High |
| Nifedipine | Moderate to high |
| Amlodipine | Mild, often clinically insignificant |
| Diltiazem, verapamil | Minimal |
Source: ESC/ESH 2023 Guidelines for the Management of Arterial Hypertension; British National Formulary, «Grapefruit juice» section.
Post-transplant immunosuppressants
Cyclosporine, tacrolimus, sirolimus, everolimus. The narrow therapeutic window makes grapefruit unacceptable: even a 30–50% rise in concentration can produce nephrotoxicity and neurotoxicity.
Source: The Transplantation Society Consensus; EMA SmPC for each molecule; KDIGO 2020 Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation.
Antiarrhythmics
Amiodarone, dronedarone, quinidine. QT prolongation is already the headline risk for this class; rising plasma levels make it worse.
Source: ESC 2020 Guidelines for the Diagnosis and Management of Atrial Fibrillation; ACC/AHA/HRS 2017.
Targeted oncology
Tyrosine kinase inhibitors are metabolized predominantly via CYP3A4 and almost all carry an explicit grapefruit warning in their SmPC: erlotinib, sunitinib, dasatinib, nilotinib, lapatinib, crizotinib, pazopanib, ibrutinib, venetoclax. Grapefruit is excluded entirely during targeted therapy.
Source: ESMO Clinical Practice Guidelines; FDA labels for each agent; NCCN Drugs & Biologics Compendium.
Antidepressants and psychotropics
| Drug | Risk |
|---|---|
| Quetiapine | High: AUC roughly doubles; EMA SmPC explicitly forbids grapefruit |
| Buspirone | High: AUC rises 4–9 fold |
| Trazodone | Moderate, FDA label warning |
| Reboxetine | Moderate, EMA SmPC: avoid |
| Oral midazolam, triazolam, high-dose alprazolam | Sedation, respiratory depression |
| Sertraline | Mild, no formal warning |
Most antidepressants do not interact with grapefruit in a clinically meaningful way because they are metabolized via CYP2D6 and CYP2C19: fluoxetine, paroxetine, escitalopram, citalopram, venlafaxine, duloxetine, mirtazapine, vortioxetine, amitriptyline, imipramine.
Source: EMA and FDA SmPC for each molecule; Bailey DG, CMAJ 2013.
Other drugs that require avoidance
- Direct oral anticoagulants: apixaban, rivaroxaban – FDA label warnings, bleeding risk.
- PDE-5 inhibitors: sildenafil, tadalafil, vardenafil – amplified hypotension, especially in patients on nitrates.
- CYP3A4-metabolized opioids: oxycodone, methadone, fentanyl – risk of sedation and respiratory depression.
- Other SmPC warnings: eplerenone, ranolazine, ticagrelor, ergotamine.
What is safe with grapefruit
- Metformin
- Levothyroxine
- Beta-blockers (metoprolol, bisoprolol, carvedilol)
- Most ARBs and ACE inhibitors
- Rosuvastatin, pravastatin, fluvastatin
- Diltiazem, verapamil
- NSAIDs (ibuprofen, naproxen, diclofenac)
These drugs use other metabolic routes – CYP2C9, CYP2D6, OATP1B1, or renal excretion.
What counts as «grapefruit»
Furanocoumarins are present in more than just grapefruit itself.
| Fruit | Effect |
|---|---|
| Grapefruit (juice and pulp) | Full |
| Pomelo and its hybrids (sweetie, oroblanco) | Full |
| Seville (bitter) orange | Full – often in marmalade and bitter liqueurs |
| Tangelo | Full |
| Sweet orange | Minimal |
| Mandarin, clementine | Minimal |
| Lemon, lime | Minimal |
Source: Bailey DG, CMAJ 2013; review by Hanley MJ et al., Expert Opinion on Drug Metabolism & Toxicology 2011.
Practical guidance
- When starting a drug from any of the groups above, exclude grapefruit, pomelo, and bitter orange entirely for the full course.
- For one-off dosing (e.g., midazolam before endoscopy), abstain for three days before the procedure.
- Time-shifting (juice in the morning, pill at night) does not help: CYP3A4 inhibition is irreversible and lasts until the enzyme regenerates.
- If your drug is not on the list, no restrictions apply.
- Uncertain? Ask the pharmacist and check the Drug Interactions section of the drug’s SmPC (FDA for the US trade name, EMA for the European one).
Sources
- Bailey DG, Dresser G, Arnold JM. Grapefruit-medication interactions: forgotten cost on patient health. CMAJ 2013;185(4):309–316.
- US FDA. Consumer Update: Grapefruit Juice and Some Drugs Don’t Mix (revised 2021).
- European Medicines Agency. Summary of Product Characteristics – per individual drug.
- British National Formulary, Appendix 1: Interactions, «Grapefruit juice» entry.
- ESC/ESH 2023 Guidelines for the Management of Arterial Hypertension.
- AHA/ACC 2018 Guideline on the Management of Blood Cholesterol.
- ESC 2020 Guidelines for the Diagnosis and Management of Atrial Fibrillation.
- ESMO Clinical Practice Guidelines (Drug-Drug Interactions section, updated annually).
- KDIGO 2020 Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation.
- Hanley MJ, Cancalon P, Widmer WW, Greenblatt DJ. The effect of grapefruit juice on drug disposition. Expert Opinion on Drug Metabolism & Toxicology 2011;7(3):267–286.
Educational resource. The information on this page does not replace a consultation with a physician and does not constitute medical advice. Decisions about substituting medications or adjusting your diet should be made together with the prescribing clinician, who knows your history and current results.