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Quinidine is used to treat many types of irregular heartbeats (arrhythmias such as atrial fibrillation). It is also used in the treatment of malaria.

How it works

Quinidine acts as a class I antiarrhythmic agent and belongs to class of medications called sodium channel blockers. It works by regulating the abnormal heartbeat in patients with heart rhythm disorders.

Common side effects

Acne-like rash, Blurred vision, Diarrhoea, Dizziness, Fatigue, Headache, Insomnia, Stomach pain, Stomach cramp, Vomiting, Weakness


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Expert advice

  • Consult your doctor if you have any of the following medical conditions: severe, uncontrolled abnormal heart rhythms, muscle weakness due to myasthenia gravis, unusual bruising while taking quinidine or similar medications.
  • Do not drive or operate machinery, as quinidine may cause dizziness and blurred vision.
  • Do not consume alcohol while taking quinidine, as it may worsen the side effects.
  • Quinidine may cause increased sensitivity to the sun light. Avoid exposure to the sun and use sunscreen or protective clothing if you must be outside for a prolonged period. 
  • Use quinidine with extreme caution in children.
  • You may be monitored with lab tests to check for side effects while on quinidine therapy. 
  • Seek immediate medical attention if you develop any of the following severe side effects: Severe allergic reactions (rash; difficulty breathing; swelling of the mouth, face, lips, or tongue); fainting; dizziness; deafness; ringing in ears; headache; dark urine; sudden change in heartbeat (fast/slow/more irregular); pale stools; jaundice.
  • Inform your doctor or dentist that you are taking quinidine, if you are having surgery, including dental surgery.
  • Tell your doctor if you are or planning to become pregnant or are breastfeeding.

Frequently asked questions


Q. Does quinidine cause thrombocytopenia?
Yes. Quinidine may cause thrombocytopenia.  Consult your doctor immediately if you develop any symptoms of thrombocytopenia (easy/ excessive bruising, reddish-purple pinpoint-sized spots in skin, prolonged bleeding from cuts, bleeding from your gums or nose, blood in urine or stools).
Q. Does quinidine cause constipation?
Quinidine causing constipation is very rare. However, please consult your doctor if you experience such side effects.
Q. How does quinidine treat malaria?
Quinidine interferes with malarial parasite’s ability to digest hemoglobin and inhibits the spontaneous formation of betahematin (hemozoin or malaria pigment), which is a toxic product resulting from digestion of hemoglobin by parasites.

Content on this page was last updated on 30 September, 2016, by Dr. Varun Gupta (MD Pharmacology)