About quinidine sulfate
Class IA antiarrhythmic
Used for
- Treats certain abnormal heart rhythms, including atrial fibrillation and ventricular arrhythmias.
- Sometimes used to treat malaria when preferred treatments are unavailable.
Usual adult dose
Heart-rhythm dosing is individualized; a common oral starting regimen is 200–300 mg every 6 hours, adjusted with ECG monitoring.
Usual dose in children
Specialist-directed dosing based on weight and heart rhythm; no standard dose.
Common side effects
- Diarrhea, nausea, vomiting, and abdominal pain.
- Ringing in the ears, headache, dizziness, or blurred vision.
- Low blood pressure or worsening heart rhythm.
- Rarely, low blood counts or severe allergic reactions.
Important warnings
- Can cause dangerous heart rhythms; ECG and electrolyte monitoring are important.
- May worsen heart failure or existing rhythm problems.
- Seek urgent care for fainting, severe dizziness, or a fast or irregular heartbeat.
- Use for malaria only under specialist guidance.
Pregnancy
Use only when needed and prescribed; evidence is limited, and untreated heart-rhythm problems can also pose risks.
Breastfeeding
Small amounts may enter breast milk; monitor the infant for diarrhea or other effects.
Interactions
- Raises digoxin levels and may increase digoxin toxicity.
- Can dangerously affect heart rhythm with other QT-prolonging medicines.
- Interactions occur with warfarin, certain antibiotics, antifungals, and seizure medicines.
- Antacids may reduce absorption; separate doses as directed.
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.