What the FDA labels say about taking them together
Tetrabenazine and thioridazine
Tetrabenazine's FDA label of November 29, 2019 names thioridazine in its drug interactions section; the thioridazine label PlainMeds reads does not name tetrabenazine.
Check it at the source: the tetrabenazine FDA label on DailyMed (effective November 29, 2019, Oceanside Pharmaceuticals); the thioridazine FDA label on DailyMed (effective November 11, 2025, Mylan Institutional Inc.).
What does the tetrabenazine label say about thioridazine?
Tetrabenazine label, drug interactionsTetrabenazine tablets cause 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.
Tetrabenazine label, warnings and precautionsThe use of tetrabenazine tablets should be avoided in combination with other drugs that are known to prolong QTc, 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 [see Drug Interactions ( 7.5 )].
Source: FDA drug label (tetrabenazine), NDA021894 (Bausch), as published by Oceanside Pharmaceuticals, effective November 29, 2019 (SPL set 5867189c-17bd-4e70-a079-c4730f9950d1), via openFDA; the full label on DailyMed
What does the thioridazine label say about tetrabenazine?
Thioridazine's label (effective November 11, 2025) does not name tetrabenazine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Thioridazine Hydrochloride), Mylan Institutional Inc., effective November 11, 2025 (SPL set 52fea941-0b47-41c1-b00d-f88150e8ab93), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Tetrabenazine | Thioridazine | |
|---|---|---|
| Labeled for | n/a | n/a |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.702 per tablet 12.5 mg tablet | $0.571 per tablet 25 mg tablet |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once