What the FDA labels say about taking them together
Quinidine and quinine
Quinidine's FDA label of February 1, 2018 names quinine in its contraindications section, and quinine's label names quinidine too. The quinidine label: “… developed thrombocytopenic purpura during prior therapy with quinidine or quinine (see WARNINGS ).”
Check it at the source: the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.); the quinine FDA label on DailyMed (effective November 9, 2023).
What does the quinidine label say about quinine?
Quinidine label, contraindicationsCONTRAINDICATIONS Quinidine is contraindicated in patients who are known to be allergic to it, or who have a history of immune thrombocytopenia or have developed thrombocytopenic purpura during prior therapy with quinidine or quinine (see WARNINGS ).
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 quinine label say about quinidine?
Quinine label, contraindications (prescription label)CONTRAINDICATIONS Quinine sulfate is contraindicated in patients with the following: Prolongation of QT interval ( 4 ) Glucose-6-phosphate dehydrogenase (G6PD) deficiency ( 4 ) Myasthenia gravis ( 4 ) Known hypersensitivity to quinine, mefloquine, or quinidine ( 4 ) Optic neuritis ( 4 ) Quinine sulfate is contraindicated in patients with the following:
Quinine label, drug interactions (prescription label)The concurrent use of quinine sulfate with astemizole and other CYP3A4 substrates with QT prolongation potential (e.g., cisapride, terfenadine, halofantrine, pimozide and quinidine ) should also be avoided [see WARNINGS AND PRECAUTIONS ( 5.3 )].
Quinine label, warnings and precautions (prescription label)At particular risk are patients with underlying structural heart disease and preexisting conduction system abnormalities, elderly patients with sick sinus syndrome, patients with atrial fibrillation with slow ventricular response, patients with myocardial ischemia or patients receiving drugs known to prolong the PR interval (e.g. verapamil) or QRS interval (e.g. flecainide or quinidine) [see CLINICAL PHARMACOLOGY ( 12.2 )].
Source: FDA drug label (Chininum sulphuricum), Boiron, effective November 9, 2023 (SPL set 33885950-2a55-11e7-8288-424c58303031), 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 | Quinine | |
|---|---|---|
| Labeled for | Atrial fibrillation | n/a |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $4.92 per tablet 324 mg tablet | $0.698 per capsule 324 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