Is Grapefruit Safe with Ketoconazole?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Avoid combining Grapefruit with Ketoconazole — Grapefruit blocks the liver enzyme (CYP3A4) that processes Ketoconazole, potentially raising Ketoconazole levels to toxic range. Consult your doctor or pharmacist.
Why this interaction occurs
Furanocoumarins irreversibly inhibit intestinal CYP3A4. Result: increased drug levels. Can increase drug levels 2-5x — dangerous with many drugs
Evidence
Evidence level: strong.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 15,791 reports mentioning Ketoconazole. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Ketoconazole + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Grapefruit interactions → · All Ketoconazole interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.