Dextromethorphan hydrobromide and quinidine sulfate

What Dextromethorphan hydrobromide and quinidine sulfate is used for

Quoted from the “Indications and Usage” section of the FDA-approved label.

Dextromethorphan hydrobromide and quinidine sulfate capsules are indicated for the treatment of pseudobulbar affect (PBA). PBA occurs secondary to a variety of otherwise unrelated neurologic conditions, and is characterized by involuntary, sudden, and frequent episodes of laughing and/or crying. PBA episodes typically occur out of proportion or incongruent to the underlying emotional state. …

— FDA label: Dextromethorphan Hydrobromide and Quinidine Sulphate, Golden State Medical Supply, Inc., effective August 4, 2026. Read the full label on DailyMed →

Label quoted: the one for the most common form (capsule, oral), Dextromethorphan Hydrobromide and Quinidine Sulphate, Golden State Medical Supply, Inc.; it covers 1 product in the FDA NDC Directory. The side effects, interactions, dosage and pregnancy quotes below come from this same label.

The FDA has 5 labels for products of this medicine (different makers and forms); uses can differ between them. Check the label that comes with your own medicine.

This page is not medical advice. Talk to your doctor or pharmacist before you start, stop or change any medicine.

Boxed warning

A boxed warning (“black box”) is the FDA’s strongest warning on a drug label, for serious or life-threatening risks.

The label quoted above has no boxed warning.

0 of 5 FDA labels for this medicine have a boxed warning.

Dextromethorphan hydrobromide and quinidine sulfate side effects

Quoted from the “Adverse Reactions” section of the FDA-approved label. Tell your doctor about any side effect that worries you.

A total of 946 patients participated in four Phase 3 controlled and uncontrolled PBA studies and received at least one dose of the combination product of dextromethorphan/quinidine in various strengths at the recommended or higher than the recommended dose. Of those patients, 393 patients were exposed for at least 180 days and 294 patients were exposed for at least one year. Median exposure was 168 days. Controlled trials enrolled only patients with either ALS or MS.

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Uncontrolled studies enrolled 136 patients with PBA secondary to a wide variety of underlying neurological conditions including stroke (45 patients) and traumatic brain injury (23 patients). Consequently, patients with other underlying neurologic diseases may experience other adverse reactions not described below. The most common adverse reactions (incidence of ≥ 3% and two-fold greater than placebo) in patients taking dextromethorphan hydrobromide and quinidine sulfate are diarrhea, dizziness, cough, vomiting, asthenia, peripheral edema, urinary tract infection, influenza, increased gamma-glutamyltransferase, and flatulence. (6.1) To report suspected adverse reactions, contact Sun Pharmaceutical Industries, Inc. at 1-800-818-4555 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience A 12-week, placebo-controlled study evaluated dextromethorphan hydrobromide and quinidine sulfate (dextromethorphan 20 mg/quinidine 10 mg) (N = 107) and a 30 mg dextromethorphan/10 mg quinidine combination (N = 110) compared to placebo (N = 109). Approximately 60% of patients had ALS and 40% had MS. Patients were 25 to 80 years of age, with a mean age of approximately 51 years. Three (3) ALS patients in each drug treatment arm and 1 ALS patient in the placebo arm died during the 12-week placebo-control period. All deaths were consistent with the natural progression of ALS. Adverse Reactions Leading to Discontinuation The most commonly reported adverse reactions (incidence ≥ 2% and greater than placebo) that led to discontinuation with the 20 mg dextromethorphan/10 mg quinidine twice daily dose were muscle spasticity (3%), respiratory failure (1%), abdominal pain (2%), asthenia (2%), dizziness (2%), fall (1%), and muscle spasms (2%). Most Common Adverse Reactions Adverse drug reactions that occurred in ≥ 3% of patients receiving the 20 mg dextromethorphan/10 mg quinidine twice daily dose, and at an incidence of ≥ 2 times placebo in short-term clinical trials in ALS and MS are provided in Table 1. Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to the rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

— FDA label: Dextromethorphan Hydrobromide and Quinidine Sulphate, Golden State Medical Supply, Inc., effective August 4, 2026. This is part of the section. Read the full label on DailyMed →

Dextromethorphan hydrobromide and quinidine sulfate drug interactions

Quoted from the “Drug Interactions” section of the FDA-approved label. Tell your pharmacist about every medicine, vitamin and herbal product you take.

Desipramine: Exposure increases 8-fold. Reduce desipramine dose and adjust based on clinical response. (7.5, 12.4) Paroxetine: Exposure increases 2-fold. Reduce paroxetine dose and adjust based on clinical response. (7.5, 12.4) Digoxin: Increased digoxin substrate plasma concentration may occur.

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(7.6) 7.1 MAOIs Do not use dextromethorphan hydrobromide and quinidine sulfate with monoamine oxidase inhibitors (MAOIs) or in patients who have taken MAOIs within the preceding 14 days [see Contraindications (4.3)]. 7.2 Drugs that Prolong QT and are Metabolized by CYP2D6 Do not use with drugs that both prolong QT interval and are metabolized by CYP2D6 (e.g., thioridazine or pimozide) [see Contraindications (4.4)]. 7.3 Drugs that Prolong QT and Concomitant CYP3A4 Inhibitors Recommend ECG in patients taking drugs with dextromethorphan hydrobromide and quinidine sulfate that prolong the QT interval and in patients taking concomitant moderate or strong CYP3A4 inhibitors [see Warnings and Precautions (5.3)]. 7.4 SSRIs and Tricyclic Antidepressants Use of dextromethorphan hydrobromide and quinidine sulfate with SSRIs or tricyclic antidepressants increases the risk of ‘serotonin syndrome’ [see Warnings and Precautions (5.6)]. 7.5 CYP2D6 Substrate The co-administration of dextromethorphan hydrobromide and quinidine sulfate with drugs that undergo extensive CYP2D6 metabolism may result in altered drug effects, due to accumulation of parent drug and/or failure of metabolite formation [see Warnings and Precautions (5.4)]. Therapy with medications that are primarily metabolized by CYP2D6 and that have a relatively narrow therapeutic index should be initiated at a low dose if a patient is receiving dextromethorphan hydrobromide and quinidine sulfate concurrently. If dextromethorphan hydrobromide and quinidine sulfate is added to the treatment regimen of a patient already receiving a drug primarily metabolized by CYP2D6, the need for a dose modification of the original medication should be considered. The extent to which CYP2D6 interactions may pose clinical problems will depend on the pharmacokinetics of the substrate involved. In cases of prodrugs whose actions are mediated by the CYP2D6-produced metabolites (for example, codeine and hydrocodone, whose analgesic and antitussive effects appear to be mediated by morphine and hydromorphone, respectively), it may not be possible to achieve the desired clinical benefits in the presence of dextromethorphan hydrobromide and quinidine sulfate due to quinidine-mediated inhibition of CYP2D6. Consider use of alternative treatment with dextromethorphan hydrobromide and quinidine sulfate when clinically indicated. Drug interactions with desipramine and paroxetine have been studied in controlled clinical trials with a higher dose combination of dextromethorphan/quinidine (dextromethorphan 30 mg/quinidine 30 mg) than dextromethorphan hydrobromide and quinidine sulfate; study results are described below.

— FDA label: Dextromethorphan Hydrobromide and Quinidine Sulphate, Golden State Medical Supply, Inc., effective August 4, 2026. This is part of the section. Read the full label on DailyMed →

Dextromethorphan hydrobromide and quinidine sulfate dosage

Quoted from the “Dosage and Administration” section of the FDA-approved label. Your own dose is the one your doctor prescribes: do not change it on your own.

Starting dose: one capsule daily by mouth for 7 days. (2.1) Maintenance dose: After 7 days, 1 capsule every 12 hours. (2.1) 2.1 Recommended Dose The recommended starting dose of dextromethorphan hydrobromide and quinidine sulfate capsules is one capsule daily by mouth for the initial seven days of therapy. On the eighth day of therapy and thereafter, the daily dose should be a total of two capsules a day, given as one capsule every 12 hours.

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The need for continued treatment should be reassessed periodically, as spontaneous improvement of PBA occurs in some patients.

— FDA label: Dextromethorphan Hydrobromide and Quinidine Sulphate, Golden State Medical Supply, Inc., effective August 4, 2026. Read the full label on DailyMed →

When Dextromethorphan hydrobromide and quinidine sulfate should not be used

Quoted from the “Contraindications” section of the FDA-approved label.

Concomitant use with quinidine, quinine, or mefloquine. (4.1) Patients with a history of quinidine, quinine or mefloquine-induced thrombocytopenia, hepatitis, or other hypersensitivity reactions. (4.2) Patients with known hypersensitivity to dextromethorphan. (4.2) Use with an MAOI or within 14 days of stopping an MAOI. Allow 14 days after stopping dextromethorphan hydrobromide and quinidine sulfate before starting an MAOI.

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(4.3) Prolonged QT interval, congenital long QT syndrome, history suggestive of torsades de pointes, or heart failure. (4.4) Complete atrioventricular (AV) block without implanted pacemaker, or patients at high risk of complete AV block. (4.4) Concomitant use with drugs that both prolong QT interval and are metabolized by CYP2D6 (e.g., thioridazine or pimozide). (4.4) 4.1 Quinidine and Related Drugs Dextromethorphan hydrobromide and quinidine sulfate contains quinidine and should not be used concomitantly with other drugs containing quinidine, quinine, or mefloquine. 4.2 Hypersensitivity Dextromethorphan hydrobromide and quinidine sulfate is contraindicated in patients with a history of dextromethorphan hydrobromide and quinidine sulfate, quinine, mefloquine or quinidine-induced thrombocytopenia, hepatitis, bone marrow depression or lupus-like syndrome. Dextromethorphan hydrobromide and quinidine sulfate is also contraindicated in patients with a known hypersensitivity to dextromethorphan (e.g. rash, hives) [see Warnings and Precautions (5.1)]. 4.3 MAOIs Dextromethorphan hydrobromide and quinidine sulfate is contraindicated in patients taking monoamine oxidase inhibitors (MAOIs) or in patients who have taken MAOIs within the preceding 14 days, due to the risk of serious and possibly fatal drug interactions, including serotonin syndrome. Allow at least 14 days after stopping dextromethorphan hydrobromide and quinidine sulfate before starting an MAOI [see Drug Interactions (7.1)]. 4.4 Cardiovascular Dextromethorphan hydrobromide and quinidine sulfate is contraindicated in patients with a prolonged QT interval, congenital long QT syndrome or a history suggestive of torsades de pointes, and in patients with heart failure [see Warnings and Precautions (5.3)]. Dextromethorphan hydrobromide and quinidine sulfate is contraindicated in patients receiving drugs that both prolong QT interval and are metabolized by CYP2D6 (e.g., thioridazine and pimozide), as effects on QT interval may be increased [see Drug Interactions (7.2)]. Dextromethorphan hydrobromide and quinidine sulfate is contraindicated in patients with complete atrioventricular (AV) block without implanted pacemakers, or in patients who are at high risk of complete AV block.

— FDA label: Dextromethorphan Hydrobromide and Quinidine Sulphate, Golden State Medical Supply, Inc., effective August 4, 2026. Read the full label on DailyMed →

Dextromethorphan hydrobromide and quinidine sulfate overdose

Quoted from the “Overdosage” section of the FDA-approved label. If someone may have taken too much, call Poison Help at 1-800-222-1222 (or 911 in an emergency).

Evaluation and treatment of dextromethorphan hydrobromide and quinidine sulfate overdose is based on experience with the individual components, dextromethorphan and quinidine.

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Metabolism of the dextromethorphan component of dextromethorphan hydrobromide and quinidine sulfate is inhibited by the quinidine component, such that adverse effects of overdose due to dextromethorphan hydrobromide and quinidine sulfate might be more severe or more persistent compared to overdose of dextromethorphan alone. During development of dextromethorphan hydrobromide and quinidine sulfate, dose combinations of dextromethorphan/quinidine containing up to 6-times higher dextromethorphan dose and 12-times higher quinidine dose were studied. The most common adverse events were mild to moderate nausea, dizziness, and headache. The most important adverse effects of acute quinidine overdose are ventricular arrhythmias and hypotension. Other signs and symptoms of overdose may include vomiting, diarrhea, tinnitus, high-frequency hearing loss, vertigo, blurred vision, diplopia, photophobia, headache, confusion, and delirium. While therapeutic doses of quinidine for treatment of cardiac arrhythmia or malaria are generally 10-fold, or more, higher than the dose of quinidine in dextromethorphan hydrobromide and quinidine sulfate, potentially fatal cardiac arrhythmia, including torsades de pointes, can occur at quinidine exposures that are possible from dextromethorphan hydrobromide and quinidine sulfate overdose. Adverse effects of dextromethorphan overdose include nausea, vomiting, stupor, coma, respiratory depression, seizures, tachycardia, hyperexcitability, and toxic psychosis. Other adverse effects include ataxia, nystagmus, dystonia, blurred vision, and changes in muscle reflexes. Dextromethorphan may cause serotonin syndrome, and this risk is increased by overdose, particularly if taken with other serotonergic agents, SSRIs or tricyclic antidepressants. 10.1 Treatment of Overdose While serum quinidine levels can be measured, electrocardiographic monitoring of the QTc interval is a better predictor of quinidine-induced arrhythmia. Treatment of hemodynamically unstable polymorphic ventricular tachycardia (including torsades de pointes) is either immediate cardioversion or, if a cardiac pacemaker is in place or immediately available, immediate overdrive pacing. After pacing or cardioversion, further management must be guided by the length of the QTc interval. Factors contributing to QTc prolongation (especially hypokalemia and hypomagnesemia) should be sought out and (if possible) aggressively corrected. Prevention of recurrent torsades de pointes may require sustained overdrive pacing or the cautious administration of isoproterenol (30 to 150 ng/kg/min).

— FDA label: Dextromethorphan Hydrobromide and Quinidine Sulphate, Golden State Medical Supply, Inc., effective August 4, 2026. This is part of the section. Read the full label on DailyMed →

Forms and how it is given

Same medicine, other forms and combinations

Prescription medicine pages on this site that share an active ingredient with this one, from the FDA NDC Directory. A combination is a different medicine: ask your pharmacist before you switch.

Other medicines with one of these active ingredients

• Brompheniramine maleate, pseudoephedrine hydrochloride, and dextromethorphan hydrobromide18 products
• Promethazine hydrochloride and dextromethorphan hydrobromidePromethazine Dm · 18 products
• Quinidine5 products
• Dextromethorphan hydrobromide, bupropion hydrochlorideAuvelity · 2 products

Companies that list this medicine

Labelers in the FDA NDC Directory: the company named on the package (maker or distributor), with the number of prescription products.

• Avanir Pharmaceuticals, Inc.1 product
• Golden State Medical Supply, Inc.1 product
• Camber Pharmaceuticals, Inc.1 product
• Otsuka America Pharmaceutical, Inc.1 product
• Sun Pharmaceutical Industries, Inc.1 product
• Teva Pharmaceuticals, Inc.1 product

FDA approval history

• NDA: New Drug Application: how a new (usually brand-name) medicine is approved.
• ANDA: Abbreviated New Drug Application: how a generic version is approved.

Generic approvals (3)

• ANDA202934Actavis Elizabeth · October 10, 2017
• ANDA218426Hetero Labs Ltd III · August 28, 2024
• ANDA204196Sun Pharm · June 3, 2026

Shortage status

The FDA drug shortage list does not show these products.

FDA Drug Shortages database →

Recalls

From FDA enforcement reports, matched by the product’s NDC code. A recall usually covers specific lots only: check the lot number on your package and ask your pharmacist. Do not stop a medicine on your own.

1. March 15, 2021 · Class II · Terminated · D-0442-2021

   CGMP Deviations: Intermittent exposure to temperature excursion during storage.

   Nuedexta (dextromethorphan HBr and quinidine sulfate) Capsules 20 mg/10 mg 60 capsules Rx only NDC 64597-301-60 Manufactured by Patheon, Inc. Whitby, ON L1N 5Z5, Canada — Cardinal Health Inc.

Official identifiers

Next steps

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• Latest FDA drug recallsAll medicines, newest first
• NuedextaBrand page: products, maker and price
• Avanir Pharmaceuticals, Inc.Maker or distributor
• Golden State Medical Supply, Inc.Maker or distributor
• Camber Pharmaceuticals, Inc.Maker or distributor
• All prescription drugs A to ZSearch by generic, brand or Spanish name

Sources

1. FDA-approved label on DailyMed (National Library of Medicine) — Dextromethorphan Hydrobromide and Quinidine Sulphate, Golden State Medical Supply, Inc., effective August 4, 2026; via openFDA, FDA data exported October 30, 2026, retrieved October 31, 2026
2. NDC Directory (openFDA) — U.S. Food and Drug Administration (FDA), FDA data exported October 30, 2026, retrieved October 31, 2026
3. Drugs@FDA (openFDA) — U.S. Food and Drug Administration (FDA), FDA data exported October 30, 2026, retrieved October 31, 2026
4. Drug recall enforcement reports (openFDA) — U.S. Food and Drug Administration (FDA), FDA data exported October 27, 2026, retrieved October 31, 2026
5. Drug shortages (openFDA) — U.S. Food and Drug Administration (FDA), FDA data exported October 30, 2026, retrieved October 31, 2026

openFDA data is provided by the FDA as is; it may be incomplete. Always rely on the label that comes with your medicine. FDA Enforcement Report search →

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