Medical Editor: John P. Cunha, DO, FACOEP
Quinidine sulfate is an antimalarial and antiarrhythmic drug used to treat or prevent many types of irregular heartbeats (heart arrhythmias such as atrial fibrillation). Quinidine sulfate is available in generic form. Common side effects of quinidine sulfate include:
- loss of appetite
- stomach pain/cramps
- a burning feeling in throat or chest (e.g., heartburn)
- heart palpitations
- angina-like chest pain
- vision problems
- changes in sleep habits
- nervousness, or
- loss of coordination
Therapy with quinidine sulfate begins with one tablet (300 mg; 249 mg of quinidine base) every 8 to 12 hours. Quinidine sulfate may interact with HIV protease inhibitors, azole antifungals, arbutamine, cisapride, fingolimod, mefloquine, mifepristone, propafenone, amiodarone, dofetilide, pimozide, procainamide, sotalol, antibiotics, ziprasidone, mesoridazine, thioridazine, antacids, barbiturates, carbamazepine, rifamycins, phenytoin, carbonic anhydrase inhibitors, aripiprazole, atomoxetine, codeine, hydrocodone, loperamide, medication for high blood pressure, quinupristin/dalfopristin, etravirine, or amprenavir/fosamprenavir. Tell your doctor all medications and supplements you use. During pregnancy, quinidine sulfate should be used only if prescribed. This medication passes into breast milk. Consult your doctor before breastfeeding.
Our Quinidine Sulfate Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
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Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Seek immediate medical attention if any of these unlikely but serious side effects occur: severe dizziness, fainting, sudden change in heartbeat (faster/slower/more irregular).
Tell your doctor immediately if any of these unlikely but serious side effects occur: vision changes, eye pain, muscle pain, unusual sweating or shakiness (signs of low blood sugar).
Tell your doctor immediately if any of these rare but very serious side effects occur: unexplained fever/signs of infection (e.g., persistent sore throat), easy bruising/bleeding, extreme tiredness, dark urine, persistent nausea/vomiting, yellowing eyes/skin, lupus-like symptoms (joint/muscle pain, chest pain, change in the amount of urine).
A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
One type of reaction (cinchonism) can occur after even a single dose of this drug. Contact your doctor of pharmacist promptly if you notice symptoms such as ringing in the ears, sudden hearing problems, headache, blurred vision, confusion. Your dosage may need to be adjusted.
Certain long-acting brands of quinidine may appear as a whole tablet in the stool. This is the empty shell left after the medicine has been absorbed by the body. It is harmless.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
Read the entire patient information overview for Quinidine Sulfate (Quinidine Sulfate Tablet, Film Coated, Extended Release)
Quinidine preparations have been used for many years, but there are only sparse data from which to estimate the incidence of various adverse reactions. The adverse reactions most frequently reported have consistently been gastrointestinal, including diarrhea, nausea, vomiting, and heartburn/esophagitis. I n one study of 245 adult outpatients who received quinidine to suppress premature ventricular contractions, the incidences of reported adverse experiences were as shown in the table below. The most serious quinidine-associated adverse reactions are described above under WARNINGS.
Adverse Experiences in a 245-Patient PVC Trial
|"upper gastrointestinal distress"||55||(22)|
|change in sleep habits||7||(3)|
Vomiting and diarrhea can occur as isolated reactions to therapeutic levels of quinidine, but they also may be the first signs of cinchonism, a syndrome that also may include tinnitus, reversible high-frequency hearing loss, deafness, vertigo, blurred vision, diplopia, photophobia, headache, confusion, and delirium. Cinchonism is most often a sign of chronic quinidine toxicity, but it may appear in sensitive patients after a single moderate dose.
A few cases of hepatotoxicity, including granulomatous hepatitis, have been reported in patients receiving quinidine. All of these have appeared during the first few weeks of therapy, and most (not all) have remitted once quinidine was withdrawn.
Autoimmune and inflammatory syndromes associated with quinidine therapy have included pneumonitis, fever, urticaria, flushing, exfoliative rash, bronchospasm, psoriasiform rash, pruritus and lymphadenopathy, hemolytic anemia, vasculitis, thrombocytopenic purpura, uveitis, angioedema, agranulocytosis, the sicca syndrome, arthralgia, myalgia, elevation in serum levels of skeletal-muscle enzymes, and a disorder resembling systemic lupus erythematosus.
Convulsions, apprehension, and ataxia have been reported, but it is not clear that these were not simply the results of hypotension and consequent cerebral hypoperfusion. There are many reports of syncope.
Acute psychotic reactions have been reported to follow the first dose of quinidine, but these reactions appear to be extremely rare.
Other adverse reactions occasionally reported include depression, mydriasis, disturbed color perception, night blindness, scotomata, optic neuritis, visual field loss, photosensitivity, and abnormalities of pigmentation.
Read the entire FDA prescribing information for Quinidine Sulfate (Quinidine Sulfate Tablet, Film Coated, Extended Release)
© Quinidine Sulfate Patient Information is supplied by Cerner Multum, Inc. and Quinidine Sulfate Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.