Arsenic Trioxide and Chlorpromazine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Chlorpromazine
No brand names on recordArsenic Trioxide
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
An increased risk of cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest)
Interaction Deep Dive
Although citing no data, the manufacturers of some phenothiazines state that concomitant use with other drugs which prolong the QT interval is not recommended. Q and T wave distortions have been observed in patients taking phenothiazines234. Even though no formal drug interaction studies have been done, phenothiazines should not be coadministered with other drugs which are also known to prolong the QTc interval, including arsenic trioxide 5.
Why it happens (mechanism)
Additive effects on QT prolongation
Literature reports
1 report — tap to read
a) QT/QTc prolongation should be expected during treatment with arsenic trioxide and torsade de pointes as well as complete heart block has been reported. Over 460 ECG tracings from 40 patients with refractory or relapsed APL treated with arsenic trioxide were evaluated for QTc prolongation. Sixteen of 40 patients (40%) had at least one ECG tracing with a QTc interval greater than 500 msec. Prolongation of the QTc was observed between 1 and 5 weeks after arsenic trioxide infusion, and then returned towards baseline by the end of 8 weeks after arsenic trioxide infusion. In these ECG evaluations, women did not experience more pronounced QT prolongation than men, and there was no correlation with age 1.
Common questions
Can I take Arsenic Trioxide and Chlorpromazine together?
An increased risk of cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Arsenic Trioxide and Chlorpromazine interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Arsenic Trioxide or Chlorpromazine need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (5)
- Product Information: Trisenox(R), arsenic trioxide. Cell Therapeutics, Inc. Seattle, WA, 2001. DailyMed
- Product Information: Compazine(R), prochlorperazine maleate spansule. GlaxoSmithKline, Research Triangle Park, NC, 2002.
- Product Information: Stelazine(R), trifluoperazine hydrochloride. GlaxoSmithKline, Research Triangle Park, NC, 2002. DailyMed
- Product Information: Thorazine(R), chlorpromazine. Smithkline Beecham Pharmaceuticals, Philadelphia, PA, 2002. DailyMed
- Product Information: Trisenox(R), arsenic trioxide. Cell Therapeutics, Inc. Seattle, WA, 2000. DailyMed
Keep reading about Chlorpromazine
Keep reading about Arsenic Trioxide
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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