Drug · FAERS side-effect profile with label screen

Chloroquine side effects: what 654 FDA adverse event reports show

Chloroquine Phosphate · 41 reaction terms · 500 drug–reaction co-reports · data 2026-09-14

Drug class

Not stated in label

Label matched

Chloroquine Phosphate (Chloroquine Phosphate)

closest FDA label found for this product string; brand list suppressed because the label is a related product, not an exact match

Who reports

654 reports · 94% serious · 146 with death outcome · 69% female

openFDA FAERS counts, all years, deduplication not applied

Used for

Chloroquine phosphate tablets are indicated for the: Treatment of uncomplicated malaria due to susceptible strains of P. falciparum, P. malariae, P. ovale, and P. vivax . Prophylaxis of malaria in geographic areas where resistance to chloroquine is not present. Treatment of extraintestinal amebiasis.

FDA label, Indications and Usage

What it is

DESCRIPTION Chloroquine Phosphate Tablet, USP, is a 4-aminoquinoline compound for oral administration. It is a white, odorless, bitter tasting, crystalline substance, freely soluble in water. Chloroquine phosphate tablet is an antimalarial and amebicidal drug.

FDA label, Description section

Boxed warning

None in the current label

How to read this page. FAERS is a spontaneous-reporting system: counts are not incidence rates and a signal is not proof of causation. Each reaction below is run through an automated screen — is the term in the FDA label (known), in the indications (the disease being treated), an administrative/coding term, or none of these (unlabeled)? That screen is mechanical text matching, not a causality assessment. The 30 hand-written Bradford Hill assessments are on the causality assessment page. Not medical advice.

Causality screen of the 27 strongest signals

Labeled adverse reaction 6Labeled (related wording) 3Reporting / coding artifact 2Lab value / disease marker 1Outcome field, not a reaction 1Not in label — unassessed 14

What the badges mean

Labeled adverse reaction The exact term appears in the label's warnings or adverse-reactions sections: a known, expected effect. The FAERS signal confirms the label rather than discovering anything.
Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
Reporting / coding artifact An administrative, monitoring or exposure term (product issue, off-label use, 'test normal', overdose...). Not a biological reaction; a high PRR here reflects how reports are coded.
Lab value / disease marker A laboratory result, investigation or disease-activity marker (antibody positive, CRP abnormal, swollen joint count) not described in the label. These usually mirror the monitored disease or testing protocol rather than a drug effect; not screened further.
Outcome field, not a reaction Death is a report outcome, not a reaction term. It is dominated by the underlying illness; see the seriousness profile and the boxed warning instead.
Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.

Strongest disproportionality signals

Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only and flags pairs whose reports are unusually skewed by sex or come mostly from consumers rather than clinicians. 14 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.

Show: hide coding/lab/outcome terms hide indication terms unlabeled only hide PRR-only

Reaction	Reports	PRR 95% CI · ROR · χ²/p	EBGM EB05 · IC025	Label screen	Serious-only & strata	Trial cross-check
Tachypnoea	24	56.9 38.4–84.3ROR 59.0 · χ² 1,261 / p 2e-276	54.5 EB05 38.5 · IC025 +4.0 3/3 methods agree	Not in label — unassessed	serious PRR 36.0 · ♀ 5% (drug 69%)	no trial data cached
Brain oedema	21	53.4 35.0–81.4ROR 55.1 · χ² 1,027 / p 1e-225	51.0 EB05 35.2 · IC025 +3.9 3/3 methods agree	Not in label — unassessed	serious PRR 33.1 · 76% consumer	no trial data cached
Covid-19 pneumonia	19	51.3 32.9–80.0ROR 52.8 · χ² 887 / p 4e-195	48.9 EB05 33.1 · IC025 +3.7 3/3 methods agree	Not in label — unassessed	serious PRR 32.0	no trial data cached
Red blood cell sedimentation rate increased	15	43.4 26.3–71.6ROR 44.4 · χ² 579 / p 3e-128	41.3 EB05 26.5 · IC025 +3.3 3/3 methods agree	Lab value / disease marker	serious PRR 30.3	no trial data cached
Ventricular fibrillation	14	40.3 24.0–67.8ROR 41.2 · χ² 498 / p 1e-110	38.4 EB05 24.3 · IC025 +3.2 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 24.8	no trial data cached
Cardiomyopathy	18	39.0 24.8–61.6ROR 40.1 · χ² 629 / p 3e-139	37.6 EB05 25.2 · IC025 +3.5 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 24.2	no trial data cached
Acute respiratory failure	19	31.8 20.4–49.6ROR 32.8 · χ² 537 / p 4e-119	30.9 EB05 20.9 · IC025 +3.4 3/3 methods agree	Not in label — unassessed	serious PRR 19.6	no trial data cached
Hypoxia (low oxygen)	32	29.3 20.9–41.1ROR 30.7 · χ² 847 / p 2e-186	28.8 EB05 21.4 · IC025 +3.8 3/3 methods agree	Not in label — unassessed	serious PRR 18.3 · ♀ 24% (drug 69%)	no trial data cached
Encephalopathy	21	27.5 18.1–41.9ROR 28.4 · χ² 510 / p 3e-113	26.9 EB05 18.5 · IC025 +3.4 3/3 methods agree	Not in label — unassessed	serious PRR 17.0 · 76% consumer	no trial data cached
Pulmonary fibrosis	16	26.9 16.6–43.6ROR 27.5 · χ² 373 / p 2e-83	26.1 EB05 17.0 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 16.7	no trial data cached
Hypercalcaemia	10	26.0 14.1–48.1ROR 26.4 · χ² 216 / p 3e-49	24.7 EB05 14.0 · IC025 +2.5 3/3 methods agree	Not in label — unassessed	serious PRR 17.1	no trial data cached
Synovitis	14	24.9 14.8–41.8ROR 25.4 · χ² 298 / p 6e-67	24.1 EB05 15.1 · IC025 +2.9 3/3 methods agree	Not in label — unassessed	serious PRR 16.0	no trial data cached
Mania	11	21.5 11.9–38.6ROR 21.8 · χ² 195 / p 1e-44	20.5 EB05 11.6 · IC025 +2.5 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 16.3	no trial data cached
Basal cell carcinoma	10	20.5 11.1–38.0ROR 20.8 · χ² 167 / p 2e-38	19.3 EB05 10.4 · IC025 +2.3 3/3 methods agree	Not in label — unassessed	serious PRR 13.0	no trial data cached
Ulcer	10	20.1 10.9–37.3ROR 20.4 · χ² 163 / p 1e-37	18.9 EB05 10.1 · IC025 +2.3 3/3 methods agree	Not in label — unassessed	serious PRR 15.6	no trial data cached
Drug eruption	11	20.0 11.1–36.0ROR 20.3 · χ² 180 / p 2e-41	19.0 EB05 10.6 · IC025 +2.4 3/3 methods agree	Labeled (related wording) related wording	serious PRR 14.2	no trial data cached
Ventricular tachycardia	10	19.4 10.5–35.8ROR 19.6 · χ² 156 / p 4e-36	18.1 EB05 9.5 · IC025 +2.3 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 12.0	no trial data cached
Pulmonary oedema	23	16.5 11.0–24.6ROR 17.0 · χ² 319 / p 1e-71	16.1 EB05 11.0 · IC025 +2.9 3/3 methods agree	Not in label — unassessed	serious PRR 10.2 · ♀ 10% (drug 69%) · 73% consumer	no trial data cached
Prescribed underdose	10	16.1 8.7–29.8ROR 16.3 · χ² 127 / p 1e-29	14.5 EB05 7.3 · IC025 +2.1 3/3 methods agree	Not in label — unassessed	serious PRR 16.9	no trial data cached
Intentional overdose	31	15.6 11.1–22.0ROR 16.3 · χ² 410 / p 2e-91	15.3 EB05 11.1 · IC025 +3.1 3/3 methods agree	Reporting / coding artifact	serious PRR 10.0 · 100% clinician	no trial data cached
Hepatitis (liver inflammation)	12	15.0 8.6–26.3ROR 15.3 · χ² 144 / p 2e-33	13.8 EB05 7.5 · IC025 +2.3 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 9.4	no trial data cached
Systemic lupus erythematosus	15	13.6 8.2–22.4ROR 13.9 · χ² 163 / p 1e-37	12.5 EB05 7.4 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious PRR 8.0	no trial data cached
Deafness	10	12.2 6.6–22.6ROR 12.4 · χ² 92 / p 4e-22	10.2 EB05 5.2 · IC025 +1.9 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 7.8	no trial data cached
Contraindicated product administered	11	11.7 6.5–21.0ROR 11.9 · χ² 97 / p 3e-23	9.8 EB05 5.2 · IC025 +2.0 3/3 methods agree	Reporting / coding artifact	serious PRR 9.0	no trial data cached
Visual acuity reduced	10	9.6 5.2–17.7ROR 9.7 · χ² 69 / p 6e-17	7.5 EB05 4.1 · IC025 +1.7 3/3 methods agree	Labeled (related wording) related wording	serious PRR 7.9	no trial data cached
Completed suicide (death by suicide)	20	7.6 5.0–11.7ROR 7.8 · χ² 109 / p 8e-26	6.7 EB05 4.5 · IC025 +2.0 3/3 methods agree	Outcome field, not a reaction	serious PRR 4.7	no trial data cached
Suicide attempt	14	7.4 4.4–12.4ROR 7.5 · χ² 71 / p 2e-17	6.2 EB05 3.8 · IC025 +1.7 3/3 methods agree	Labeled (related wording) related wording	serious PRR 4.6	no trial data cached

Trial evidence (ClinicalTrials.gov)

Trial cross-check not yet run for this drug (ClinicalTrials.gov pull covers the 800 most-reported drugs first).

Most frequently reported reactions

By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.

Reaction	Reports	PRR 95% CI · ROR · χ²/p	EBGM EB05 · IC025	Label screen	Serious-only & strata	Trial cross-check
Hypoxia (low oxygen)	32	29.3 20.9–41.1ROR 30.7 · χ² 847 / p 2e-186	28.8 EB05 21.4 · IC025 +3.8 3/3 methods agree	Not in label — unassessed	serious PRR 18.3 · ♀ 24% (drug 69%)	no trial data cached
Intentional overdose	31	15.6 11.1–22.0ROR 16.3 · χ² 410 / p 2e-91	15.3 EB05 11.1 · IC025 +3.1 3/3 methods agree	Reporting / coding artifact	serious PRR 10.0 · 100% clinician	no trial data cached
Tachypnoea	24	56.9 38.4–84.3ROR 59.0 · χ² 1,261 / p 2e-276	54.5 EB05 38.5 · IC025 +4.0 3/3 methods agree	Not in label — unassessed	serious PRR 36.0 · ♀ 5% (drug 69%)	no trial data cached
Pulmonary oedema	23	16.5 11.0–24.6ROR 17.0 · χ² 319 / p 1e-71	16.1 EB05 11.0 · IC025 +2.9 3/3 methods agree	Not in label — unassessed	serious PRR 10.2 · ♀ 10% (drug 69%) · 73% consumer	no trial data cached
Encephalopathy	21	27.5 18.1–41.9ROR 28.4 · χ² 510 / p 3e-113	26.9 EB05 18.5 · IC025 +3.4 3/3 methods agree	Not in label — unassessed	serious PRR 17.0 · 76% consumer	no trial data cached
Brain oedema	21	53.4 35.0–81.4ROR 55.1 · χ² 1,027 / p 1e-225	51.0 EB05 35.2 · IC025 +3.9 3/3 methods agree	Not in label — unassessed	serious PRR 33.1 · 76% consumer	no trial data cached
Completed suicide (death by suicide)	20	7.6 5.0–11.7ROR 7.8 · χ² 109 / p 8e-26	6.7 EB05 4.5 · IC025 +2.0 3/3 methods agree	Outcome field, not a reaction	serious PRR 4.7	no trial data cached
Acute respiratory failure	19	31.8 20.4–49.6ROR 32.8 · χ² 537 / p 4e-119	30.9 EB05 20.9 · IC025 +3.4 3/3 methods agree	Not in label — unassessed	serious PRR 19.6	no trial data cached
Covid-19 pneumonia	19	51.3 32.9–80.0ROR 52.8 · χ² 887 / p 4e-195	48.9 EB05 33.1 · IC025 +3.7 3/3 methods agree	Not in label — unassessed	serious PRR 32.0	no trial data cached
Cardiomyopathy	18	39.0 24.8–61.6ROR 40.1 · χ² 629 / p 3e-139	37.6 EB05 25.2 · IC025 +3.5 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 24.2	no trial data cached
Pulmonary fibrosis	16	26.9 16.6–43.6ROR 27.5 · χ² 373 / p 2e-83	26.1 EB05 17.0 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 16.7	no trial data cached
Systemic lupus erythematosus	15	13.6 8.2–22.4ROR 13.9 · χ² 163 / p 1e-37	12.5 EB05 7.4 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious PRR 8.0	no trial data cached
Red blood cell sedimentation rate increased	15	43.4 26.3–71.6ROR 44.4 · χ² 579 / p 3e-128	41.3 EB05 26.5 · IC025 +3.3 3/3 methods agree	Lab value / disease marker	serious PRR 30.3	no trial data cached
Suicide attempt	14	7.4 4.4–12.4ROR 7.5 · χ² 71 / p 2e-17	6.2 EB05 3.8 · IC025 +1.7 3/3 methods agree	Labeled (related wording) related wording	serious PRR 4.6	no trial data cached
Synovitis	14	24.9 14.8–41.8ROR 25.4 · χ² 298 / p 6e-67	24.1 EB05 15.1 · IC025 +2.9 3/3 methods agree	Not in label — unassessed	serious PRR 16.0	no trial data cached

Unlabeled candidate signals

These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.

Tachypnoea — n=24, PRR 56.9
Brain oedema — n=21, PRR 53.4
Hypoxia — n=32, PRR 29.3
Encephalopathy — n=21, PRR 27.5
Pulmonary oedema — n=23, PRR 16.5

Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.

Common questions

What are the most reported side effects of Chloroquine?

In FDA FAERS, the most frequently co-reported reaction terms for Chloroquine are hypoxia, tachypnoea, pulmonary oedema, encephalopathy, brain oedema, acute respiratory failure. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.

Does Chloroquine have an FDA boxed warning?

No. The FDA label retrieved for Chloroquine has no boxed warning; see the label's Warnings and Precautions for the recognised risks.

Do FAERS signals prove that Chloroquine causes these side effects?

No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.

Sources & methods

FDA label via openFDA (set ID ff199f31-bfda-45f8-adbd-4662f7054f1c, effective 20251210; matched on openfda.generic_name.exact:"CHLOROQUINE PHOSPHATE")
Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA count= aggregation, field patient.drug.openfda.generic_name.exact, 41 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction
Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
Seriousness and sex counts from openFDA count=serious, patient.patientsex, seriousnessdeath

Page generated 2026-10-08. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.