Drug interactions
Efavirenz + Perphenazine
Severity: Moderate
Efavirenz and Perphenazine: 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
Both drugs can prolong the QT interval, so the combination may raise the risk of ventricular arrhythmias. Efavirenz may also affect perphenazine metabolism.
What this interaction means in plain words
Efavirenz and Perphenazine 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; Perphenazine belongs to Central Nervous System.
Why it happens
Additive QT prolongation; efavirenz may alter CYP2D6-mediated perphenazine metabolism.
What to do
Obtain a baseline ECG, correct electrolytes, and monitor QTc. Watch for loss of antipsychotic effect or adverse effects and adjust dose.
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 Perphenazine
- Ibutilide + Perphenazine Contraindicated
- Perphenazine + Pimozide Contraindicated
- Perphenazine + Thioridazine Contraindicated
- Adagrasib + Perphenazine Major
- Alfentanil + Perphenazine Major
- Amiodarone + Perphenazine Major
Frequently asked questions
Can I take Efavirenz with Perphenazine?
MediHelp rates the interaction as moderate. Efavirenz and Perphenazine 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. Both drugs can prolong the QT interval, so the combination may raise the risk of ventricular arrhythmias. Efavirenz may also affect perphenazine metabolism.
How serious is the interaction between Efavirenz and Perphenazine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Obtain a baseline ECG, correct electrolytes, and monitor QTc. Watch for loss of antipsychotic effect or adverse effects and adjust dose.
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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