Drug interactions
Efavirenz + Mirtazapine
Severity: Moderate
Efavirenz and Mirtazapine: moderate 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
Efavirenz may induce CYP3A4 and lower mirtazapine concentrations, potentially reducing antidepressant effect. Both drugs have also been associated with QT prolongation, though the added risk is modest at usual doses.
What this interaction means in plain words
Efavirenz and Mirtazapine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Efavirenz belongs to Anti Virals; Mirtazapine belongs to Central Nervous System.
Why it happens
CYP3A4 induction by efavirenz increases mirtazapine metabolism, plus possible additive QT effects.
What to do
Monitor depressive symptoms and titrate mirtazapine to response. Consider an ECG if other QT-prolonging drugs or electrolyte disturbances are present.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Efavirenz
- Cobimetinib + Efavirenz Contraindicated
- Dienogest / estradiol valerate + Efavirenz Contraindicated
- Dihydroergotamine intranasal + Efavirenz Contraindicated
- Dihydroergotamine + Efavirenz Contraindicated
- Doravirine + Efavirenz Contraindicated
- Efavirenz + Elbasvir / grazoprevir Contraindicated
Other interactions of Mirtazapine
- Isocarboxazid + Mirtazapine Contraindicated
- Mirtazapine + Phenelzine Contraindicated
- Mirtazapine + Pimozide Contraindicated
- Mirtazapine + Procarbazine Contraindicated
- Mirtazapine + Rasagiline Contraindicated
- Mirtazapine + Selegiline Contraindicated
Frequently asked questions
Can I take Efavirenz with Mirtazapine?
MediHelp rates the interaction as moderate. Efavirenz and Mirtazapine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Efavirenz may induce CYP3A4 and lower mirtazapine concentrations, potentially reducing antidepressant effect. Both drugs have also been associated with QT prolongation, though the added risk is modest at usual doses.
How serious is the interaction between Efavirenz and Mirtazapine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor depressive symptoms and titrate mirtazapine to response. Consider an ECG if other QT-prolonging drugs or electrolyte disturbances are present.
What other medicines interact with Efavirenz?
MediHelp also lists interactions of Efavirenz with, for example, Cobimetinib, Dienogest / estradiol valerate, Dihydroergotamine intranasal. The full list is on the Efavirenz page.
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