What the FDA labels say about taking them together
Propranolol and quinidine
Propranolol's FDA label of January 15, 2026 names quinidine in its drug interactions section, and quinidine's label names propranolol too. The propranolol label: “… CYP2D6, such as amiodarone, cimetidine, delavudin, fluoxetine, paroxetine, quinidine, and ritonavir.”
Check it at the source: the propranolol FDA label on DailyMed (effective January 15, 2026, Mylan Pharmaceuticals Inc.); the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.).
What does the propranolol label say about quinidine?
Propranolol label, drug interactionsSubstrates or Inhibitors of CYP2D6 Blood levels and/or toxicity of propranolol may be increased by co-administration with substrates or inhibitors of CYP2D6, such as amiodarone, cimetidine, delavudin, fluoxetine, paroxetine, quinidine, and ritonavir.
Inderal Xl label (ANI Pharmaceuticals, Inc., August 27, 2026), drug interactionsImpact of Other Drugs on Propranolol CYP2D6, CYP1A2 and CYP2C19 Inhibitors: CYP2D6 inhibitors (e.g. bupropion, fluoxetine, paroxetine, quinidine), CYP1A2 inhibitors (e.g., ciprofloxacin, enoxamine, fluvoxamine) and CYP2C19 inhibitors (e.g., fluconazole, fluvoxamine, ticlopidine) increase exposure to propranolol when co-administered with INDERAL XL.
Source: FDA drug label (Inderal Xl, NDA021438), ANI Pharmaceuticals, Inc., effective August 27, 2026 (SPL set ac196ff5-9215-402b-bc57-69aa87f8bade), via openFDA
Source: FDA drug label (Propranolol Hydrochloride), Mylan Pharmaceuticals Inc., effective January 15, 2026 (SPL set b94dcec7-7633-4a33-9cea-48161adeaf93), via openFDA; the full label on DailyMed
What does the quinidine label say about propranolol?
Quinidine label, drug interactionsCoadministration of propranolol usually does not affect quinidine pharmacokinetics, but in some studies the β-blocker appeared to cause increases in the peak serum levels of quinidine, decreases in quinidine's volume of distribution, and decreases in total quinidine clearance.
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
| Propranolol | Quinidine | |
|---|---|---|
| Labeled for | High blood pressure, Angina, Atrial fibrillation, Migraine | Atrial fibrillation |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.0493 per tablet 20 mg tablet | $4.92 per tablet 324 mg tablet |
| Shortage now | In shortage | 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