Drug interactions
Arsenic trioxide + Efavirenz
Severity: Major
Arsenic trioxide and Efavirenz: 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
Arsenic trioxide causes marked QT prolongation and torsades de pointes, and efavirenz adds further QT risk. The combination raises the risk of life-threatening arrhythmia.
What this interaction means in plain words
Arsenic trioxide and Efavirenz 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.
Arsenic trioxide belongs to Oncology; Efavirenz belongs to Anti Virals.
Why it happens
Additive prolongation of cardiac repolarization.
What to do
Avoid if possible; otherwise obtain baseline and serial ECGs and keep potassium and magnesium within normal range.
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 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 Arsenic trioxide
- Amiodarone + Arsenic trioxide Contraindicated
- Amisulpride + Arsenic trioxide Contraindicated
- Arsenic trioxide + Clomipramine Contraindicated
- Arsenic trioxide + Dronedarone Contraindicated
- Arsenic trioxide + Fluphenazine Contraindicated
- Arsenic trioxide + Gemifloxacin Contraindicated
Frequently asked questions
Can I take Arsenic trioxide with Efavirenz?
MediHelp rates the interaction as major. Arsenic trioxide and Efavirenz 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. Arsenic trioxide causes marked QT prolongation and torsades de pointes, and efavirenz adds further QT risk. The combination raises the risk of life-threatening arrhythmia.
How serious is the interaction between Arsenic trioxide and Efavirenz?
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 if possible; otherwise obtain baseline and serial ECGs and keep potassium and magnesium within normal range.
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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