Is Grapefruit Juice Safe with Diltiazem?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Limit or avoid grapefruit juice consumption. Separate timing will not eliminate the risk as CYP3A4 inhibition is irreversible for 24–72 hours. Use alternative beverages.
Why this interaction occurs
Grapefruit juice inhibits intestinal CYP3A4 which is involved in diltiazem's first-pass metabolism. This raises diltiazem blood levels, increasing the risk of hypotension, bradycardia, and enhanced pharmacodynamic effects.
Evidence
Evidence level: moderate.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 73,173 reports mentioning Diltiazem. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Diltiazem + 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 Juice interactions → · All Diltiazem interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.