Drug interactions
Efavirenz + Venlafaxine
Severity: Minor
Efavirenz and Venlafaxine: 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
Efavirenz may induce CYP3A4 and lower venlafaxine exposure, though venlafaxine is cleared mainly by CYP2D6 so the effect is likely small. Both drugs can also affect cardiac conduction, and venlafaxine has been linked to QT prolongation in overdose.
What this interaction means in plain words
Efavirenz and Venlafaxine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Efavirenz belongs to Anti Virals; Venlafaxine belongs to Central Nervous System.
Why it happens
Efavirenz induces CYP3A4, a minor pathway of venlafaxine metabolism, and both drugs may have minor additive QT effects.
What to do
Monitor for loss of antidepressant response and titrate the venlafaxine dose to clinical effect. Check an ECG if other QT-prolonging drugs or cardiac risk factors are present.
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 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 Venlafaxine
- Isocarboxazid + Venlafaxine Contraindicated
- Methylene blue + Venlafaxine Contraindicated
- Phenelzine + Venlafaxine Contraindicated
- Procarbazine + Venlafaxine Contraindicated
- Rasagiline + Venlafaxine Contraindicated
- Safinamide + Venlafaxine Contraindicated
Frequently asked questions
Can I take Efavirenz with Venlafaxine?
MediHelp rates the interaction as minor. Efavirenz and Venlafaxine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Efavirenz may induce CYP3A4 and lower venlafaxine exposure, though venlafaxine is cleared mainly by CYP2D6 so the effect is likely small. Both drugs can also affect cardiac conduction, and venlafaxine has been linked to QT prolongation in overdose.
How serious is the interaction between Efavirenz and Venlafaxine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for loss of antidepressant response and titrate the venlafaxine dose to clinical effect. Check an ECG if other QT-prolonging drugs or cardiac risk factors 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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