What the FDA labels say about taking them together
Quinidine and timolol
Quinidine's FDA label of February 1, 2018 names timolol in its drug interactions section, and timolol's label names quinidine too. The timolol label: “… Potentiated systemic beta-blockade has been reported during combined treatment with quinidine and timolol.”
Check it at the source: the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.); the timolol FDA label on DailyMed (effective June 27, 2025, Thea Pharma Inc.).
What does the quinidine label say about timolol?
Quinidine label, drug interactionsNon-interactions of quinidine with other drugs: Quinidine has no clinically significant effect on the pharmacokinetics of diltiazem, flecainide, mephenytoin, metoprolol, propafenone, propranolol, quinine, timolol, or tocainide.
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
What does the timolol label say about quinidine?
Timolol Maleate label (Bausch & Lomb Americas Inc., November 4, 2024), drug interactionsDRUG INTERACTIONS Concomitant use with systemic beta-blockers may potentiate systemic beta-blockade. ( 7.1 ) Oral or intravenous calcium antagonists may cause atrioventricular conduction disturbances, left ventricular failure, and hypotension. ( 7.2 ) Catecholamine-depleting drugs may have additive effects and produce hypotension and/or marked bradycardia. ( 7.3 ) Digitalis and calcium antagonists may have additive effects in prolonging atrioventricular conduction time. ( 7.4 ) Potentiated systemic beta-blockade (e.g., decreased heart rate) has been reported during combined treatment with quinidine and timolol.
Timolol Maleate label (Bausch & Lomb Americas Inc., March 26, 2025), drug interactionsCYP2D6 Inhibitors Potentiated systemic beta-blockade (e.g., decreased heart rate, depression) has been reported during combined treatment with CYP2D6 inhibitors (e.g., quinidine, SSRIs) and timolol.
Source: FDA drug label (Timolol Maleate, NDA021516), Bausch & Lomb Americas Inc., effective November 4, 2024 (SPL set b686bbad-1ef7-4b94-a316-4d182a40b89a), via openFDA
Source: FDA drug label (Timolol Maleate, NDA020330), Bausch & Lomb Americas Inc., effective March 26, 2025 (SPL set 581f80f7-4419-49e2-867d-40443c75409f), via openFDA
Source: FDA drug label (BETIMOL), Thea Pharma Inc., effective June 27, 2025 (SPL set 3ae775f4-340c-4bf4-aa49-8a31daba0f8b), 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
| Quinidine | Timolol | |
|---|---|---|
| Labeled for | Atrial fibrillation | Glaucoma, High blood pressure, Migraine |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $4.92 per tablet 324 mg tablet | $0.774 per mL 0.5% eye drops |
| 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