What the FDA labels say about taking them together
Haloperidol and procainamide
Haloperidol's FDA label (Haloperidol Decanoate) of February 19, 2025 names procainamide in its drug interactions section; the procainamide label PlainMeds reads does not name haloperidol. The haloperidol label: “Pharmacodynamic Interactions Since QTc interval-prolongation has been observed during haloperidol treatment, caution is advised when prescribing to a patient with QT-prolongation conditions or to patients receiving …”
Check it at the source: the haloperidol FDA label on DailyMed (effective April 23, 2026, PD-Rx Pharmaceuticals, Inc.); the procainamide FDA label on DailyMed (effective February 17, 2025, Caplin Steriles Limited).
What does the haloperidol label say about procainamide?
Haloperidol Decanoate label (Patriot Pharmaceuticals LLC, February 19, 2025), drug interactionsPharmacodynamic Interactions Since QTc interval-prolongation has been observed during haloperidol treatment, caution is advised when prescribing to a patient with QT-prolongation conditions or to patients receiving medications known to prolong the QTc-interval (see WARNINGS, Cardiovascular Effects ). Examples include (but are not limited to): Class 1A antiarrhythmics (e.g., procainamide, quinidine, disopyramide);
Source: FDA drug label (Haloperidol Decanoate, NDA018701), Patriot Pharmaceuticals LLC, effective February 19, 2025 (SPL set 9f0f42a8-5f7c-4be7-93ef-3ec225502cc6), via openFDA
Source: FDA drug label (Haloperidol), PD-Rx Pharmaceuticals, Inc., effective April 23, 2026 (SPL set 533b0b4c-cbd6-4ec0-a333-8b04b5b43a1d), via openFDA; the full label on DailyMed
What does the procainamide label say about haloperidol?
Procainamide's label (effective February 17, 2025) does not name haloperidol in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Procainamide Hydrochloride), Caplin Steriles Limited, effective February 17, 2025 (SPL set fcaa5e9a-3c8a-4796-aa87-626268b6cf60), 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
| Haloperidol | Procainamide | |
|---|---|---|
| Labeled for | Schizophrenia | n/a |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $15.60 per mL 100 mg/mL vial | n/a |
| Shortage now | A presentation being discontinued | 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