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Drug Profile

The information on this site is intended to supplement and enhance, not replace, the advice of a physician who is familiar with your medical history. Decisions about your health should always be made ONLY after detailed conversation with your doctor.

Limited Use [what does this mean?]
Generic drug name: quinidine (KWIN i deen)
GENERIC: available FAMILY: Drugs for Abnormal Heart Rhythm
Find the drug label by searching at DailyMed.

Pregnancy and Breast-feeding Warnings [top]

Pregnancy Warning

No data are available for quinidine. Use during pregnancy only for clear medical reasons. Tell your doctor if you are pregnant or thinking of becoming pregnant before you take this drug.

Breast-feeding Warning

Quinidine is excreted in human milk. Because of the potential for serious adverse effects in nursing infants, you should not take this drug while nursing.

Safety Warnings For This Drug [top]


In the National Heart, Lung, and Blood Institute’s Cardiac Arrhythmia Suppression Trial (CAST) (a long-term, multicentered, randomized, double-blind study), in patients with asymptomatic non-life-threatening ventricular (the large chambers of the heart) arrhythmias (rhythm disturbances) who had a heart attack more than six days but less than two years previous, deaths or nonfatal cardiac arrest were seen in 7.7% of those patients treated with encainide or flecainide, members of the Class 1 group of antiarrhythmic drugs, compared to 3.0% in patients receiving an inactive sugar pill or placebo.

Because of the known ability of the Class 1 drugs, such as quinidine, to cause rhythm disturbances, and the lack of evidence of improved survival for any antiarrhythmic drug in patients without life-threatening heart rhythm disturbances, the use of the Class 1 drugs should be reserved for patients with life-threatening rhythm disturbances of the ventricles. These warnings now appear in the FDA-approved product labeling, or package insert, for all Class 1 drugs, including: disopyramide (NORPACE and generics), flecainide (TAMBOCOR), mexiletine (MEXITIL and generics), moricizine (ETHMOZINE), procainamide (PROCANBID and generics), propafenone (RYTHMOL), quinidine (DURAQUIN, QUINAGLUTE DURA-TABS, QUINIDEX, and generics), and tocainide (TONOCARD).


In many trials of antiarrhythmic therapy for non-life-threatening arrhythmias, active antiarrhythmic therapy has resulted in increased mortality; the risk of active therapy is probably greatest in patients with structural heart disease.

In the case of quinidine used to prevent or defer recurrence of atrial [small chambers of the heart] flutter/fibrillation, the best available data come from a meta-analysis [statistical summary] described under CLINICAL PHARMACOLOGY—Clinical Effects [a section of the drug’s professional product labeling]. In the patients studied, the mortality associated with the use of quinidine was more than three times as great as the mortality associated with the use of placebo.

Another meta-analysis, also described under CLINICAL PHARMACOLOGY—Clinical Effects, showed that in patients with various non-life-threatening ventricular arrhythmias, the mortality associated with the use of quinidine was consistently greater than that associated with the use of any of a variety of alternative antiarrhythmics.


When this drug was used to treat rhythm disturbances of the small chambers of the heart (atria), it provided no survival advantage and a higher risk of serious adverse effects than older drugs such as digoxin (LANOXICAPS, LANOXIN), the beta blockers, calcium channel blockers diltiazem and verapamil.[1],[2]

Facts About This Drug [top]

Quinidine slows the heart rate and decreases irregular heartbeats (arrhythmias). If your kidney function is impaired, you will need to take less than the usual dose.

Many people who are taking quinidine or another drug in its family have relatively mild disturbances in their heart rhythm and no symptoms of underlying heart disease. The vast majority of these people do not need these drugs, and there is no evidence that using them improves health. In fact, most of the drugs in this family...

Quinidine slows the heart rate and decreases irregular heartbeats (arrhythmias). If your kidney function is impaired, you will need to take less than the usual dose.

Many people who are taking quinidine or another drug in its family have relatively mild disturbances in their heart rhythm and no symptoms of underlying heart disease. The vast majority of these people do not need these drugs, and there is no evidence that using them improves health. In fact, most of the drugs in this family have severe adverse effects that are sometimes worse, and even more life-threatening, than the irregular heartbeats they treat. All of these drugs can also cause new irregularities in your heartbeat.

If you have an irregular heartbeat, without any symptoms of underlying heart disease, you should not be exposed to the dangers of a drug that has no health benefit for your condition.[3] If you are taking quinidine or another drug in its family for an irregular heartbeat (arrhythmia), talk to your doctor and find out whether you also have symptoms of underlying heart disease. If not, discuss the possibility of stopping the drug.

There have been 5 case reports of patients on quinidine/quinine therapy that developed thrombocytopenia (abnormally low platelet count) after intermittently taking quinine for leg cramps or gouty arthritis and after taking quinidine intermittently for palpitations.[4]

Some people are very sensitive to quinidine and may have difficulty breathing, changes in vision, dizziness, fever, headache, ringing in ears, or skin rash when taking this drug. Since there is a narrow range between a helpful and a harmful amount of this drug, call your doctor immediately if you experience these adverse effects (as well as any of those listed under Adverse Effects).

Before You Use This Drug [top]

Do not use if you have or have had:

  • complete heart block
  • digitalis toxicity with heart block
  • pregnancy or are planning to become pregnant, or are breast-feeding

Tell your doctor if you have or have had:

  • allergies to drugs
  • asthma or emphysema
  • incomplete heart block or other heart problems
  • digitalis toxicity
  • kidney or liver problems
  • increased secretion of thyroid hormones
  • low blood potassium or other electrolyte disorders that can result from severe diarrhea or vomiting, or dialysis
  • myasthenia gravis
  • psoriasis
  • difficulty stopping bleeding

Tell your doctor about any other drugs you take, including aspirin, herbs, vitamins, and other nonprescription products.

When You Use This Drug [top]

  • Do not stop taking this drug suddenly. Your doctor must give you a schedule to lower your dose gradually, to prevent serious changes in heart function.
  •    Wear a medical identification bracelet or carry a card stating that you take quinidine.
  •    If you plan to have any surgery, including dental, tell your doctor that you take this drug.

How to Use This Drug [top]

  • If you miss a dose, take it as soon as you remember, but skip it if it is almost time for your next scheduled dose. Do not take double doses.
  • Do not share your medication with others.
  • Take the drug at the same time(s) each day.
  • Take with food or milk.
  • Do not break, chew, or crush this drug. Take your last dose of the day at least an hour before bedtime.
  • Store at room temperature with lid on tightly. Do not store in the bathroom. Do not expose to heat, moisture, or strong light. Keep out of reach of children.

Interactions with Other Drugs [top]

The following drugs, biologics (e.g., vaccines, therapeutic antibodies), or foods are listed in Evaluations of Drug Interactions 2003 as causing “highly clinically significant” or “clinically significant” interactions when used together with any of the drugs in this section. In some sections with multiple drugs, the interaction may have been reported for one but not all drugs in this section, but we include the interaction because the drugs in this section are similar to one another. We have also included potentially serious interactions listed in the drug’s FDA-approved professional package insert or in published medical journal articles. There may be other drugs, especially those in the families of drugs listed below, that also will react with this drug to cause severe adverse effects. Make sure to tell your doctor and pharmacist the drugs you are taking and tell them if you are taking any of these interacting drugs:

acetazolamide, amiodarone, arbutamine, AVELOX, AZOPT, bendroflumethiazide, benzthiazide, brinzolamide, CALAN SR, chlorothiazide, cimetidine, codeine, CORDARONE, COUMADIN, COVERA-HS, cyclopenthiazide, cyclosporine, cyclothiazide, delavirdine, DIAMOX, dichlorphenamide, digoxin, DILANTIN, DIURIL, dorzolamide, ENDURON, flumethazide, fluvoxamine, FORTOVASE, GLUCOVANCE, halofantrine, hydrochlorothiazide, hydroflumethazide, ISOPTIN SR, itraconazole, ketoconazole, LANOXICAPS, LANOXIN, LUMINAL, metformin, methazolamide, methyclothiazide, mizolastine, moxifloxacin, NAQUA, NATURETIN-5, NEORAL, NIZORAL, NORVIR, phenobarbital, phenytoin, polythiazide, potassium citrate, PRIFTIN, propafenone, RENESE, RESCRIPTOR, RIFADIN, rifampin, rifapentine, RIMACTANE, ritonavir, RYTHMOL, SANDIMMUNE, saquinavir, SERLECT, sertindole, sodium acetate, sodium bicarbonate, SOLFOTON, sparfloxacin, SPORANOX, TAGAMET, THAM, trichlormethiazide, tromethamine, TRUSOPT, TUBARINE, tubocurarine, verapamil, VERELAN, warfarin, xipamide, zotepine, ZAGAM.

Adverse Effects [top]

Call your doctor immediately if you experience:

  • blurred—or any change in—vision
  • abdominal pain and/or yellow eyes or skin
  • confusion or delirium
  • disturbed color perception
  • intolerance of light
  • dizziness or fainting
  • fever
  • severe headache
  • ringing in ears or loss of hearing
  • skin rash, hives, or itching
  • painful joints
  • wheezing, shortness of breath
  • unusual bleeding or bruising
  • unusually fast heartbeat
  • unusual tiredness or weakness

Call your doctor if these symptoms continue:

  • bitter taste in mouth
  • confusion
  • diarrhea
  • flushing or itching skin
  • loss of appetite
  • muscle weakness
  • nausea, vomiting, stomach pain

Periodic Tests[top]

Ask your doctor which of these tests should be done periodically while you are taking this drug:

  • blood pressure
  • complete blood count
  • heart function tests, such as electrocardiogram (ECG, EKG)
  • kidney function tests
  • liver function tests
  • blood levels of potassium and quinidine

last reviewed December 31, 2023