What the FDA labels say about taking them together
Prazosin and quinidine
Prazosin's FDA label of March 6, 2026 names quinidine in its drug interactions section; the quinidine label PlainMeds reads does not name prazosin.
Check it at the source: the prazosin FDA label on DailyMed (effective March 6, 2026, Prasco Laboratories); the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.).
What does the prazosin label say about quinidine?
Prazosin label, drug interactionsDrug Interactions Prazosin hydrochloride capsules have been administered without any adverse drug interaction in limited clinical experience to date with the following: (1) cardiac glycosides– digitalis and digoxin; (2) hypoglycemics–insulin, chlorpropamide, phenformin, tolazamide, and tolbutamide; (3) tranquilizers and sedatives–chlordiazepoxide, diazepam, and phenobarbital; (4) antigout–allopurinol, colchicine, and probenecid; (5) antiarrhythmics–procainamide, propranolol (see WARNINGS however), and quinidine; and (6) analgesics, antipyretics and anti-inflammatories–propoxyphene, aspirin, indomethacin, and phenylbutazone.
Source: FDA drug label (Prazosin Hydrochloride), NDA017442 (Pfizer), as published by Prasco Laboratories, effective March 6, 2026 (SPL set cbe89216-7dea-43d7-b12e-44ccfb69af3d), via openFDA; the full label on DailyMed
What does the quinidine label say about prazosin?
Quinidine's label (effective February 1, 2018) does not name prazosin in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Quinidine Gluconate), Sun Pharmaceutical Industries, Inc., effective February 1, 2018 (SPL set 5023f053-fcc4-4c2c-aa59-9ec198ad185e), 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
| Prazosin | Quinidine | |
|---|---|---|
| Labeled for | High blood pressure | Atrial fibrillation |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.0842 per capsule 1 mg capsule | $4.92 per tablet 324 mg tablet |
| 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