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Quinidine Side Effects

The most commonly reported side effects of quinidine include off label use, fall, and product use in unapproved indication, based on 4,580 FDA adverse event reports from 2004 to 2025. 6.6% of reports found the drug to be ineffective.

Quinidine side effects

Percentages show how often each reaction appears relative to total reports for quinidine.

1
Drug Ineffective6.6%304
2
Off Label Use5.3%241
3
Fall4.8%222
4
Product Use In Unapproved Indication4.6%209
5
Death4.4%201
6
Fatigue3.9%178
7
Dizziness3.9%178
8
Therapy Interrupted3.5%160
9
Diarrhoea3.4%156
10
Nausea3.0%136
11
Depression2.4%109
12
Somnolence2.4%109
13
Gait Disturbance2.3%105
14
Condition Aggravated2.3%105
15
Dysphagia2.3%104

These are voluntary reports and do not establish that quinidine caused these reactions.

Report severity

42.9%Serious1,965 reports
18.3%Hospitalizations840 reports
8.8%Fatal404 reports

Seriousness is determined by the reporter, not by OpenClaim.

Quinidine drug interactions

Other drugs that appear in adverse event reports alongside quinidine. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Dextromethorphan54.5%2,494
2
Dalfampridine4.2%192
3
Dimethyl2.8%127
4
Pimavanserin2.1%95
5
Fingolimod2.0%90
6
Amiodarone-hydrochloride1.6%75
7
Natalizumab1.6%71
8
Sodium-oxybate1.3%59
9
Teriflunomide1.2%57
10
Levodopa1.1%52
11
Riluzole1.1%51
12
Levetiracetam1.0%48
13
Carbidopa1.0%48
14
Interferon0.9%41
15
Procainamide-hydrochloride0.9%41

Taken alongside

1
Dextromethorphan24.7%1,129
2
Ergocalciferol10.1%463
3
Acetaminophen8.5%391
4
Gabapentin8.3%379
5
Aspirin7.7%353
6
Levothyroxine-sodium7.0%320
7
Baclofen6.4%291
8
Atorvastatin-calcium5.9%270
9
Omeprazole5.5%251
10
Clonazepam5.3%241
11
Amlodipine5.2%238
12
Furosemide4.9%225
13
Albuterol4.6%212
14
Metoprolol4.6%211
15
Lorazepam4.6%209

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports quinidine side effects

51.4% of quinidine adverse event reports involve female patients and 30.5% involve male patients. The largest age group is adult at 56%. These figures reflect who reports side effects, not underlying risk.

Sex

Female51.4%
Male30.5%
Unknown18.1%

Age group

< 21.8%
2–111.9%
12–171.3%
18–6455.7%
65+39.4%

What is quinidine used for

Conditions and purposes for which patients were taking quinidine when the adverse event was reported.

Abdominal Pain UpperAbnormal BehaviourAdjuvant TherapyAdverse EventAffect LabilityAffective DisorderAggressionAgitationAmyotrophic Lateral SclerosisAngerAngiopathyAnxietyArrhythmiaArrhythmia SupraventricularAtrial Fibrillation

Showing 15 of 266 indications

Quinidine brand names and reporting trend

Quinidine is sold under brand names including Cardioquin, Cin-quin, Quinalan.

Brand names

Cardioquin861
Cin-quin177
Quinalan76

Quarterly reports (20042025)

20052010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking quinidine with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.