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Chloroquine Side Effects

The most commonly reported side effects of chloroquine include rheumatoid arthritis, pain, and joint swelling, based on 3,384 FDA adverse event reports from 2004 to 2025. 17.3% of reports found the drug to be ineffective.

Chloroquine side effects

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

1
Drug Ineffective17.3%587
2
Rheumatoid Arthritis11.7%396
3
Pain10.3%350
4
Joint Swelling8.1%275
5
Fatigue8.0%271
6
Arthralgia8.0%270
7
Drug Intolerance6.6%222
8
Rash6.2%211
9
Off Label Use6.2%209
10
Condition Aggravated5.3%181
11
Treatment Failure5.3%180
12
Therapeutic Product Effect Decreased5.1%171
13
Arthropathy5.0%169
14
Alopecia5.0%168
15
Nausea4.8%164

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

Report severity

69.1%Serious2,339 reports
29.8%Hospitalizations1,008 reports
7.7%Fatal259 reports

Seriousness is determined by the reporter, not by OpenClaim.

Chloroquine drug interactions

Other drugs that appear in adverse event reports alongside chloroquine. 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
Adalimumab45.1%1,525
2
Methotrexate20.5%695
3
Abatacept19.5%661
4
Etanercept18.9%640
5
Leflunomide15.5%524
6
Hydroxychloroquine-sulfate12.3%415
7
Tocilizumab11.9%404
8
Rituximab10.9%370
9
Sulfasalazine10.5%356
10
Prednisone9.6%324
11
Infliximab9.5%320
12
Tofacitinib9.0%306
13
Certolizumab-pegol7.9%266
14
Golimumab7.5%253
15
Alendronate-sodium4.1%140

Taken alongside

1
Prednisone27.1%918
2
Methotrexate25.3%857
3
Folic-acid17.2%581
4
Acetaminophen14.2%482
5
Levothyroxine-sodium9.8%333
6
Omeprazole8.4%283
7
Ergocalciferol8.2%277
8
Celecoxib7.4%250
9
Leflunomide7.2%242
10
Sulfasalazine6.6%225
11
Calcium6.6%222
12
Aspirin6.3%214
13
Pantoprazole-sodium5.9%200
14
Tofacitinib5.3%179
15
Hydrochlorothiazide5.2%176

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 chloroquine side effects

76.8% of chloroquine adverse event reports involve female patients and 17.6% involve male patients. The largest age group is adult at 66%. These figures reflect who reports side effects, not underlying risk.

Sex

Female76.8%
Male17.6%
Unknown5.5%

Age group

< 20.5%
2–110.7%
12–172.1%
18–6466.3%
65+30.5%

What is chloroquine used for

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

Abortion InducedAccidental OverdoseAlopeciaAnalgesic TherapyAntiphospholipid SyndromeAntipyresisArthralgiaArthritisAutoimmune DisorderAdverse EventBack PainBipolar DisorderBlau SyndromeBody Temperature IncreasedBone Disorder

Showing 15 of 115 indications

Chloroquine brand names and reporting trend

Chloroquine is sold under the brand name Aralen Phosphate W/ Primaquine Phosphate.

Brand names

Aralen Phosphate W/ Primaquine Phosphate3,227

Quarterly reports (20042025)

20052010201520202025

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

Taking chloroquine with another medication?

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