Drug interactions
Mifepristone + Mirtazapine
Severity: Major
Mifepristone and Mirtazapine: major interaction.
Last updated Sources: US FDA label
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
Mifepristone, particularly at the higher doses used for Cushing's syndrome, prolongs the QT interval. Mirtazapine may add to this effect, and mifepristone also inhibits CYP3A4, which may raise mirtazapine exposure.
What this interaction means in plain words
Mifepristone and Mirtazapine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Mifepristone belongs to Endocrine; Mirtazapine belongs to Central Nervous System.
Why it happens
Additive QT prolongation, plus CYP3A4 inhibition by mifepristone that may increase mirtazapine levels.
What to do
Avoid the combination where possible when mifepristone is used at Cushing's doses. If it is needed, monitor ECG and electrolytes and use the lowest effective mirtazapine dose.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Mirtazapine
- Isocarboxazid + Mirtazapine Contraindicated
- Mirtazapine + Phenelzine Contraindicated
- Mirtazapine + Pimozide Contraindicated
- Mirtazapine + Procarbazine Contraindicated
- Mirtazapine + Rasagiline Contraindicated
- Mirtazapine + Selegiline Contraindicated
Other interactions of Mifepristone
- Apixaban + Mifepristone Contraindicated
- Argatroban + Mifepristone Contraindicated
- Cisapride + Mifepristone Contraindicated
- Cortisone + Mifepristone Contraindicated
- Cyclosporin + Mifepristone Contraindicated
- Dabigatran etexilate + Mifepristone Contraindicated
Frequently asked questions
Can I take Mifepristone with Mirtazapine?
MediHelp rates the interaction as major. Mifepristone and Mirtazapine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Mifepristone, particularly at the higher doses used for Cushing's syndrome, prolongs the QT interval. Mirtazapine may add to this effect, and mifepristone also inhibits CYP3A4, which may raise mirtazapine exposure.
How serious is the interaction between Mifepristone and Mirtazapine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination where possible when mifepristone is used at Cushing's doses. If it is needed, monitor ECG and electrolytes and use the lowest effective mirtazapine dose.
What other medicines interact with Mirtazapine?
MediHelp also lists interactions of Mirtazapine with, for example, Isocarboxazid, Phenelzine, Pimozide. The full list is on the Mirtazapine page.
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