Reviewed on 8/1/2022

What Is Quinidine and How Does It Work?

Quinidine is a prescription medication used for the treatment of arrhythmias and malaria

What Are Side Effects Associated with Using Quinidine?

Common side effects of Quinidine include:

  • chest pain,
  • pounding heartbeats,
  • dizziness,
  • heartburn,
  • nausea,
  • vomiting,
  • diarrhea,
  • flushing (sudden warmth, redness, or tingly feeling),
  • weakness,
  • tiredness, and
  • pain or tenderness at the injection site (may last for several weeks)

Serious side effects of Quinidine include:

  • hives,
  • difficulty breathing,
  • swelling of the face, lips, tongue, or throat,
  • fast or pounding heartbeats,
  • fluttering in your chest,
  • shortness of breath,
  • sudden dizziness,
  • vomiting,
  • diarrhea,
  • confusion,
  • ringing in the ears,
  • hearing loss,
  • severe eye redness,
  • vision problems,
  • increased sensitivity to light,
  • wheezing,
  • chest tightness,
  • easy bruising,
  • unusual bleeding,
  • pale or yellowed skin,
  • stomach pain (upper right side),
  • dark urine,
  • fever,
  • chills,
  • sore throat,
  • mouth sores,
  • swollen glands,
  • skin itching, flaking, blistering, peeling, or rash on your cheeks or arms that worsens in sunlight,
  • muscle or joint pain,
  • dry mouth, and
  • trouble swallowing

Rare side effects of Quinidine include:

  • none 

This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.


Heart Disease: Symptoms, Signs, and Causes See Slideshow

What Are Dosages of Quinidine?

 Adult and pediatric dosage


  • 200mg (as sulfate)
  • 300mg (as sulfate)
  • Tablet, extended-release
  • 300mg (as sulfate)
  • 324mg (as gluconate)
  • Injectable solution
  • 80mg/mL (as gluconate) - discontinued from U.S. market
  • Arrhythmias
  • Adult dosage
  • Quinidine Sulfate
    • Test Dose: 200 mg orally quinidine sulfate several hours before full dosage
    • Atrial fibrillation: 300-400 mg orally every 6 hours
    • PSVT: 400-600 mg orally every 2-3 hours until paroxysm terminated
    • Atrial/Ventricular Premature Contractions: 200-300 mg orally every 6-8 hours
    • Maint: 200-400 mg orally every 6-8 hours or 600 mg of SR orally every 8-12 hours
    • No more than 3-4 g/day
  • Quinidine Gluconate
    • 324-660 mg orally every 8-12 hours
    • Maintenance: 648 mg orally every 12 hours OR 324-660 mg orally every 8 hours
    • PSVT: 400 - 600 mg orally every 2-3 hours until paroxysm is terminated
    • IV: Usual below 5 mg/kg (but may need up to 10 mg/kg) at 0.25 mg/kg/min

Pediatric dosage

  • Quinidine sulfate: 30 mg/kg/day or 900 mg/m²/day orally given in 5 divided doses OR 15-60 mg/kg/day divided every 6 hours orally
  • Test dose: 2 mg/kg orally quinidine sulfate; test dose not to exceed 200 mg
  • Malaria
  • Adult dosage
  • Quinidine Gluconate: It is no longer available in the US market
    • Regimen I
      • Load: 24 mg/kg diluted in 250 mL NS IV infusion over 4 hours  
      • Maintenance: Follow by 12 mg/kg IV infusion over 4 hours every 8 hours beginning 8 hours after initiation of loading dose except in patients able to swallow the same doses of quinidine are administered using 300 mg quinidine sulfate tablets
    • Regimen II
      • Load: 10 mg/kg diluted in 5 mL/kg NS IV over 1-2 hours  
      • Maintenance: Follow by 0.02 mg/kg/min continuous IV infusion; in patients able to swallow oral quinine is administered every 8 hr to give as much quinine as the patient received in quinidine every 8 hours
      • Oral regimen: 300 mg quinidine or 650 mg quinine oral every 8 hours for 3 days (Africa and South America) or 7 days (Southeast Asia) or until parasitemia is reduced to 1%
  • Pediatric dosage
    • Load: 10 mg/kg diluted in 5 mL/kg NS IV over 1-2 hours
    • Maintenance: Follow by 0.02 mg/kg/min continuous IV infusion; in patients able to swallow oral quinine is administered every 8 hr to give as much quinine as the patient received in quinidine every 8 hours
    • Oral regimen: 650 mg quinine orally every 8 hours  for 3 days (Africa and South America) or 7 days (Southeast Asia) or until parasitemia is reduced to 1%

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Other Drugs Interact with Quinidine?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first

  • Quinidine has severe interactions with at least 73 other drugs.
  • Quinidine has serious interactions with at least 218 other drugs.
  • Quinidine has moderate interactions with at least 251 other drugs.
  • Quinidine has minor interactions with at least 21 other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.


In the U.S., 1 in every 4 deaths is caused by heart disease. See Answer

What Are Warnings and Precautions for Quinidine?


Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Quinidine?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Quinidine?”


  • Use caution in acute rheumatic fever, acute thyrotoxicosis, CHF, subacute bacterial endocarditis, syncope
  • Electrolyte imbalances due to severe N/V, diarrhea, and eating disorders may occur; use caution
  • IV administration requires continuous cardiac & blood pressure monitoring
  • The dose should be adjusted within range to achieve desired therapeutic effects within therapeutic plasma concentration and in absence of toxic SE
  • Avoid grapefruit juice
  • Very high dosages may induce abortion in pregnant women due to the oxytocic effect
  • Extended-release not recommended in children
  • When quinidine is administered to patients with atrial flutter/fibrillation, the desired pharmacologic reversion to sinus rhythm may (rarely) be preceded by a slowing of atrial rate with a consequent increase in the rate of beats conducted to ventricles; the resulting ventricular rate may be very high (greater than 200 beats per minute) and poorly tolerated; this hazard may be decreased if partial atrioventricular block is achieved prior to initiation of quinidine therapy, using conduction-reducing drugs such as digitalis, verapamil, diltiazem, or a β-receptor blocking agent
  • In patients with sick sinus syndrome, quinidine has been associated with marked sinus node depression and bradycardia
  • Renal or hepatic dysfunction causes the elimination of quinidine to be slowed, while congestive heart failure causes a reduction in quinidine's apparent volume of distribution. Any of these conditions can lead to quinidine toxicity if the dosage is not appropriately reduced
  • Because quinidine opposes atrial and A-V nodal effects of vagal stimulation, physical or pharmacological vagal maneuvers undertaken to terminate paroxysmal supraventricular tachycardia may be ineffective in patients receiving quinidine
  • In patients without implanted pacemakers who are at high risk of the complete atrioventricular block(eg, those with digitalis intoxication, second-degree atrioventricular block, or severe intraventricular conduction defects), quinidine should be used only with caution

Proarrhythmic effects

  • As with other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs QT interval, and can lead to torsades de pointes, a life-threatening ventricular arrhythmia; the risk of torsades is increased by bradycardia, hypokalemia, hypomagnesemia, or high serum levels of quinidine, but may appear in absence of any of these risk factors
  • The best predictor of this arrhythmia appears to be the length of QTc interval; quinidine should be used with extreme care in patients who have preexisting long-QT syndromes, who have histories of torsades de pointes of any cause, or who have previously responded to quinidine (or other drugs that prolong ventricular repolarization) with marked lengthening of the QT c interval


  • Quinidine-induced thrombocytopenia is an immune-mediated disorder characterized by a drug-dependent antibody that is itself nonreactive, but when the soluble drug is present at pharmacologic concentrations, binds tightly to specific platelet membrane glycoproteins, causing platelet destruction
  • Serologic testing for the quinidine-specific antibody is commercially available and may be useful for identifying the specific cause of thrombocytopenia in individual cases; testing is important because a patient with quinidine-dependent antibodies should not be re-exposed to quinidine
  • Typically, a patient with immune thrombocytopenia will have taken the drug for about 1 week or inter­mittently over a longer period of time (possibly years) before presenting with petechiae or bruising
  • Systemic symptoms, such as lightheadedness, chills, fever, nausea, and vomiting, often may precede bleeding events; thrombocytopenia may be severe; patients should have risk/benefit reevaluated in order to continue treatment with quinidine; if the drug is stopped, symptoms usually resolve within 1 or 2 days and platelet count returns to normal in less than 1 week
  • If quinidine is not stopped, there is a risk of fatal hemorrhage; the onset of thrombocytopenia may be more rapid upon re-exposure

Drug interaction overview

  • Interactions with coadministered drugs can alter serum concentration and activity of quinidine, leading either to toxicity or to lack of efficacy if the dose of quinidine is not appropriately modified
  • Diltiazem significantly decreases clearance and increases t1/2 of quinidine, but quinidine does not alter the kinetics of diltiazem
  • Drugs that alkalinize urine (carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics) reduce renal elimination of quinidine
  • By pharmacokinetic mechanisms not well understood, quinidine levels are increased by coadministration of amiodarone or cimetidine
  • Very rarely, and again by mechanisms, not under­stood, quinidine levels are decreased by coadministration of nifedipine
  • Hepatic elimination of quinidine may be accelerated by coadministration of drugs ( phenobarbital, phenytoin, rifampin) that induce production of cytochrome P450 IIIA4; perhaps because of competition for P450 IIIA4 metabolic pathway, quinidine levels rise when ketoconazole is coadministered
  • Coadministration of propranolol usually does not affect quinidine pharmacokinetics, but in some studies, the β-blocker appeared to cause increases in peak serum levels of quinidine, decreases in quinidine's volume of distribution, and decreases in total quinidine clearance
  • The effects (if any) of coadministration of other beta-blockers on quinidine pharmacokinetics have not been adequately studied; hepatic clearance of quinidine is significantly reduced during coadministration of verapamil, with corresponding increases in serum levels and half-life
  • The rate and extent of quinidine absorption may be affected by changes in dietary salt intake; a decrease in dietary salt intake may lead to an increase in plasma quinidine concentrations

Pregnancy & Lactation

  • There are no adequate and well-controlled studies on pregnant women
  • Animal reproductive studies have not been conducted


  • Lactation: crosses into breast milk, use extreme caution (AAP Committee states compatible with nursing)

Health Solutions From Our Sponsors