Drug interactions
Grapefruit + Primaquine
Severity: Minor
Grapefruit and Primaquine: minor interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Grapefruit juice inhibits intestinal CYP3A4 and might increase primaquine exposure. Primaquine is mainly metabolised by other routes (MAO-A and CYP2D6), so the effect is likely small and poorly documented.
What this interaction means in plain words
Grapefruit and Primaquine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Inhibition of intestinal CYP3A4 by grapefruit constituents, which may modestly reduce primaquine first-pass metabolism.
What to do
No routine action is needed; patients may be advised to avoid large amounts of grapefruit juice during primaquine therapy and to report increased adverse effects.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Primaquine
- Pimozide + Primaquine Contraindicated
- Amiodarone + Primaquine Major
- Amisulpride + Primaquine Major
- Anagrelide + Primaquine Major
- Arsenic trioxide + Primaquine Major
- Asenapine + Primaquine Major
Frequently asked questions
Can I take Grapefruit with Primaquine?
MediHelp rates the interaction as minor. Grapefruit and Primaquine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Grapefruit juice inhibits intestinal CYP3A4 and might increase primaquine exposure. Primaquine is mainly metabolised by other routes (MAO-A and CYP2D6), so the effect is likely small and poorly documented.
How serious is the interaction between Grapefruit and Primaquine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine action is needed; patients may be advised to avoid large amounts of grapefruit juice during primaquine therapy and to report increased adverse effects.
What other medicines interact with Primaquine?
MediHelp also lists interactions of Primaquine with, for example, Pimozide, Amiodarone, Amisulpride. The full list is on the Primaquine page.
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