Atypical antidepressant (NaSSA)
Mirtazapine 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 Mirtazapine (Mirtazapine) at 7.5mg, 15mg, 30mg, 45mg depends on whether the active ingredient Mirtazapine 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 Atypical antidepressant (NaSSA) class that go through CYP3A4 first-pass metabolism, regular grapefruit consumption can raise plasma levels of Mirtazapine by a clinically meaningful margin and amplify side effects.
What to do with Mirtazapine
According to the prescribing information for Mirtazapine, if grapefruit is flagged as an interaction, the safest practice is to avoid grapefruit entirely or to discuss timing with the prescriber. Mirtazapine antagonises presynaptic α2-adrenergic autoreceptors and heteroreceptors, increasing noradrenaline and serotonin release. A small occasional serving may be tolerable; daily large servings around the time of Mirtazapine dosing are not recommended at 7.5mg, 15mg, 30mg, 45mg.
Frequently asked questions
Can I eat grapefruit while on Mirtazapine? ▾
For some Atypical antidepressant (NaSSA) medications, grapefruit is best avoided or limited because of CYP3A4 inhibition. Whether Mirtazapine specifically is affected depends on Mirtazapine; the prescribing information lists this. When in doubt, ask the pharmacist or check the patient leaflet.
How much grapefruit is too much with Mirtazapine? ▾
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 Mirtazapine at 7.5mg, 15mg, 30mg, 45mg, individual tolerance varies; the cautious choice is to avoid grapefruit if any interaction is mentioned.
Products containing Mirtazapine
More on Mirtazapine
- With alcoholMirtazapine and alcohol — is it safe to drink?
- With foodShould Mirtazapine be taken with food?
- Side effectsMirtazapine side effects: common, rare and warning signs
- Dosage guideMirtazapine dosage guide: how much to take and when
- OnsetHow fast does Mirtazapine start working?
- DurationHow long does Mirtazapine last?
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