What the FDA labels say about taking them together
Thioridazine and ziprasidone
Ziprasidone's FDA label of July 20, 2026 names thioridazine in its contraindications section; thioridazine's label does not name ziprasidone itself but warns about its class (Atypical antipsychotics). The ziprasidone label: “… drugs, but was approximately 14 msec less than the prolongation observed for thioridazine.”
Check it at the source: the thioridazine FDA label on DailyMed (effective November 11, 2025, Mylan Institutional Inc.); the ziprasidone FDA label on DailyMed (effective July 20, 2026, Apotex Corp.).
What does the thioridazine label say about ziprasidone?
Thioridazine's label does not name ziprasidone itself; it warns about its class (Atypical antipsychotics):
Thioridazine label, boxed warningAnalyses of seventeen placebo-controlled trials (modal duration of 10 weeks), largely in patients taking atypical antipsychotic drugs, revealed a risk of death in drug-treated patients of between 1.6 to 1.7 times the risk of death in placebo-treated patients.
Thioridazine label, boxed warningDue to its potential for significant, possibly life threatening, proarrhythmic effects, thioridazine should be reserved for use in the treatment of schizophrenic patients who fail to show an acceptable response to adequate courses of treatment with other antipsychotic drugs, either because of insufficient effectiveness or the inability to achieve an effective dose due to intolerable adverse effects from those drugs (see WARNINGS , CONTRAINDICATIONS , and INDICATIONS ).
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
What does the ziprasidone label say about thioridazine?
Ziprasidone label, contraindicationsTherefore, ziprasidone should not be given with: dofetilide, sotalol, quinidine, other Class Ia and III anti-arrhythmics, mesoridazine, thioridazine, chlorpromazine, droperidol, pimozide, sparfloxacin, gatifloxacin, moxifloxacin, halofantrine, mefloquine, pentamidine, arsenic trioxide, levomethadyl acetate, dolasetron mesylate, probucol or tacrolimus. other drugs that have demonstrated QT prolongation as one of their pharmacodynamic effects and have this effect described in the full prescribing information as a contraindication or a boxed or bolded warning [see Warnings and Precautions (5.3) ].
Ziprasidone label, warnings and precautionsThe mean increase in QTc from baseline for ziprasidone ranged from approximately 9 to 14 msec greater than for four of the comparator drugs (risperidone, olanzapine, quetiapine, and haloperidol), but was approximately 14 msec less than the prolongation observed for thioridazine.
Source: FDA drug label (ziprasidone hydrochloride), Apotex Corp., effective July 20, 2026 (SPL set ccfd5ba2-7271-f3dd-4c98-7418c1a4b54a), 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
| Thioridazine | Ziprasidone | |
|---|---|---|
| Labeled for | n/a | Bipolar disorder, Schizophrenia |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.571 per tablet 25 mg tablet | $0.269 per capsule 20 mg capsule |
| 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