Prometrium and grapefruit: a real interaction?
Grapefruit is famous as the juice that interacts with medications, and the warning is real for a number of drugs. Whether it matters specifically for Prometrium (Progesterone) at 100mg, 200mg depends on whether the active ingredient Progesterone is metabolised by CYP3A4 in the gut wall and how much that pathway contributes to first-pass metabolism.
The CYP3A4 mechanism
Grapefruit (and its juice) inhibits CYP3A4 enzymes in the gut wall, increasing the absorbed dose of medications metabolised by that enzyme. For drugs in the Hormones and Birth Control class that go through CYP3A4 first-pass metabolism, regular grapefruit consumption can raise plasma levels of Progesterone by a clinically meaningful margin and amplify side effects.
What to do with Prometrium
According to the prescribing information for Progesterone, if grapefruit is flagged as an interaction, the safest practice is to avoid grapefruit entirely or to discuss timing with the prescriber. Progesterone in Prometrium binds to progesterone receptors and modulates gene expression in reproductive and other tissues. A small occasional serving may be tolerable; daily large servings around the time of Prometrium dosing are not recommended at 100mg, 200mg.
Frequently asked questions
Can I eat grapefruit while on Prometrium? ▾
For some Hormones and Birth Control medications, grapefruit is best avoided or limited because of CYP3A4 inhibition. Whether Prometrium specifically is affected depends on Progesterone; the prescribing information lists this. When in doubt, ask the pharmacist or check the patient leaflet.
How much grapefruit is too much with Prometrium? ▾
For drugs where the interaction matters, even modest daily grapefruit intake (one whole grapefruit or one large glass of juice) can shift drug levels noticeably. For Prometrium at 100mg, 200mg, individual tolerance varies; the cautious choice is to avoid grapefruit if any interaction is mentioned.
More on Prometrium
- With alcoholPrometrium and alcohol — is it safe to drink?
- With foodShould Prometrium be taken with food?
- Side effectsPrometrium side effects: common, rare and warning signs
- Dosage guidePrometrium dosage guide: how much to take and when
- OnsetHow fast does Prometrium start working?
- DurationHow long does Prometrium last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.