Thioridazine and Tetrabenazine Interaction
Drug interaction information between Thioridazine and Tetrabenazine.
Thioridazine and Tetrabenazine have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Thioridazine and Tetrabenazine. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
Both medications can change the heart's electrical rhythm. Taking them together increases the risk of a dangerous heart rhythm problem.
FDA Label Information
7.5 Drugs That Cause QTc Prolongation Tetrabenazine causes a small prolongation of QTc (about 8 msec), concomitant use with other drugs that are known to cause QTc prolongation should be avoided, these including antipsychotic medications (e.g., chlorpromazine, haloperidol, thioridazine, ziprasidone), antibiotics (e.g., moxifloxacin), Class 1A (e.g., quinidine, procainamide) and Class III (e.g., amiodarone, sotalol) antiarrhythmic medications or any other medications known to prolong the QTc interval. 7.6 Neuroleptic Drugs The risk for Parkinsonism, NMS, and akathisia may be increased by...
Thioridazine Also Interacts With
- Fluoxetine major
- Paroxetine major
- Rolapitant major
- Abiraterone moderate
- Darifenacin moderate
Tetrabenazine Also Interacts With
- Deutetrabenazine major
- Valbenazine major
- Olanzapine moderate
- Risperidone moderate
- Ziprasidone moderate
Frequently Asked Questions
What SPL severity band is on file for Thioridazine + Tetrabenazine?
Compiled FDA labeling labels this pair moderate. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Thioridazine has 17 labeled pairs on file vs Tetrabenazine's 16. In the moderate band specifically: Thioridazine has 3 (also Abiraterone, Darifenacin); Tetrabenazine has 9 (also Olanzapine, Risperidone, Ziprasidone, Haloperidol).
What mechanism field is on file for Thioridazine and Tetrabenazine?
Both medications can change the heart's electrical rhythm. Taking them together increases the risk of a dangerous heart rhythm problem.
Thioridazine carries more major-labeled pairs than Tetrabenazine
SPL source-record counts only. This page's band is moderate · classes on file: Thioridazine (Typical Antipsychotic (Phenothiazine)); Tetrabenazine (VMAT2 Inhibitor).
Thioridazine has 3 major-labeled pairs vs Tetrabenazine's 2. This page itself is in the moderate band, not the major band.
3 major · 3 moderate · 11 minor · 17 total
- Other moderate peers for Thioridazine
- Abiraterone
- Darifenacin
2 major · 9 moderate · 5 minor · 16 total
- Other moderate peers for Tetrabenazine
- Olanzapine
- Risperidone
- Ziprasidone
- Haloperidol
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.