Chlorothiazide side effects: what 1,253 FDA adverse event reports show

Chlorothiazide · Diuril · 46 reaction terms · 617 drug–reaction co-reports · data 2026-09-14

Drug class

Thiazide Diuretic

FDA label (Established Pharmacologic Class) · compare the class

Brand names

Diuril

openFDA label

Who reports

1,253 reports · 80% serious · 198 with death outcome · 49% female

openFDA FAERS counts, all years, deduplication not applied

Used for

DIURIL is indicated as adjunctive therapy in edema associated with congestive heart failure, hepatic cirrhosis, and corticosteroid and estrogen therapy. DIURIL has also been found useful in edema due to various forms of renal dysfunction such as nephrotic syndrome, acute glomerulonephritis, and chronic renal failure.

FDA label, Indications and Usage

What it is

DESCRIPTION DIURIL ® (chlorothiazide) is a diuretic and antihypertensive. It is 6-chloro-2 H -1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide.

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 21 strongest signals

Labeled adverse reaction 1Labeled (related wording) 3Likely indication confounding 3Reporting / coding artifact 1Lab value / disease marker 1Not in label — unassessed 12

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.
Likely indication confounding The term appears in the label's indications: reports probably describe the disease being treated (or its progression), not a drug effect. Classic confounding by indication.
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.
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. 25 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
Pulmonary hypertension	36	28.9 20.9–39.8ROR 29.7 · χ² 940 / p 1e-206	28.4 EB05 21.5 · IC025 +3.8 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious PRR 20.9	no trial data cached
Pulmonary arterial hypertension	23	26.5 17.6–39.7ROR 26.9 · χ² 538 / p 3e-119	25.9 EB05 18.2 · IC025 +3.4 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious PRR 19.5	no trial data cached
Fluid overload	22	25.0 16.5–37.8ROR 25.4 · χ² 482 / p 3e-107	24.5 EB05 17.0 · IC025 +3.3 3/3 methods agree	Not in label — unassessed	serious PRR 22.2	no trial data cached
Respiratory distress	35	21.2 15.3–29.4ROR 21.8 · χ² 655 / p 1e-144	21.0 EB05 15.8 · IC025 +3.5 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 15.0	no trial data cached
Acute respiratory failure	20	17.5 11.3–27.0ROR 17.8 · χ² 295 / p 2e-66	17.0 EB05 11.4 · IC025 +2.9 3/3 methods agree	Labeled (related wording) related wording	serious PRR 12.6 · 90% clinician	no trial data cached
Aspiration	11	17.0 9.4–30.6ROR 17.1 · χ² 150 / p 9e-35	15.8 EB05 8.4 · IC025 +2.3 3/3 methods agree	Not in label — unassessed	serious PRR 11.4	no trial data cached
Hypoxia (low oxygen)	32	15.3 10.9–21.5ROR 15.7 · χ² 413 / p 4e-92	15.0 EB05 10.9 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 11.2 · 90% clinician	no trial data cached
Complication associated with device	12	15.2 8.7–26.7ROR 15.3 · χ² 145 / p 9e-34	13.9 EB05 7.6 · IC025 +2.3 3/3 methods agree	Not in label — unassessed	serious PRR 17.8	no trial data cached
Respiratory failure	62	14.2 11.2–18.1ROR 14.9 · χ² 751 / p 1e-165	14.1 EB05 11.3 · IC025 +3.3 3/3 methods agree	Labeled (related wording) related wording	serious PRR 10.2 · 90% clinician	no trial data cached
Serotonin syndrome	15	13.1 7.9–21.7ROR 13.3 · χ² 156 / p 4e-36	12.0 EB05 7.1 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious PRR 9.5	no trial data cached
Shock	14	10.3 6.1–17.3ROR 10.4 · χ² 108 / p 1e-25	8.8 EB05 5.2 · IC025 +2.1 3/3 methods agree	Not in label — unassessed	serious PRR 7.4	no trial data cached
Liver function test increased	13	10.2 5.9–17.5ROR 10.3 · χ² 99 / p 1e-23	8.6 EB05 5.0 · IC025 +2.0 3/3 methods agree	Labeled (related wording) related wording	serious PRR 11.4	no trial data cached
Anhedonia	16	10.1 6.2–16.5ROR 10.2 · χ² 123 / p 9e-29	8.8 EB05 5.4 · IC025 +2.1 3/3 methods agree	Not in label — unassessed	serious PRR 8.0	no trial data cached
Viral infection	20	10.1 6.5–15.6ROR 10.2 · χ² 155 / p 8e-36	9.0 EB05 5.9 · IC025 +2.3 3/3 methods agree	Not in label — unassessed	serious PRR 9.1	no trial data cached
Oxygen saturation decreased	32	9.6 6.8–13.5ROR 9.8 · χ² 239 / p 4e-54	9.0 EB05 6.5 · IC025 +2.5 3/3 methods agree	Lab value / disease marker	serious PRR 7.4	no trial data cached
Fear	15	9.3 5.6–15.3ROR 9.4 · χ² 103 / p 2e-24	7.9 EB05 4.8 · IC025 +2.0 3/3 methods agree	Not in label — unassessed	serious PRR 9.0	no trial data cached
Renal injury	15	8.4 5.1–13.8ROR 8.5 · χ² 90 / p 1e-21	7.1 EB05 4.4 · IC025 +1.9 3/3 methods agree	Not in label — unassessed	serious PRR 6.0	no trial data cached
Cardiac arrest (heart stopping)	40	8.1 6.0–11.0ROR 8.3 · χ² 242 / p 7e-55	7.6 EB05 5.7 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious PRR 5.7	no trial data cached
Renal failure acute	18	7.0 4.4–11.1ROR 7.1 · χ² 87 / p 6e-21	6.1 EB05 4.0 · IC025 +1.8 3/3 methods agree	Likely indication confounding term in indications; also in warnings	serious PRR 5.1	no trial data cached
Fluid retention	20	6.6 4.3–10.2ROR 6.7 · χ² 89 / p 2e-21	5.8 EB05 3.9 · IC025 +1.8 3/3 methods agree	Not in label — unassessed	serious PRR 5.3 · ♀ 75% (drug 49%)	no trial data cached
Device dislocation	11	4.2 2.4–7.6ROR 4.3 · χ² 24 / p 4e-7	3.7 EB05 2.2 · IC025 +0.9 3/3 methods agree	Reporting / coding artifact	serious PRR 3.3	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
Respiratory failure	62	14.2 11.2–18.1ROR 14.9 · χ² 751 / p 1e-165	14.1 EB05 11.3 · IC025 +3.3 3/3 methods agree	Labeled (related wording) related wording	serious PRR 10.2 · 90% clinician	no trial data cached
Cardiac arrest (heart stopping)	40	8.1 6.0–11.0ROR 8.3 · χ² 242 / p 7e-55	7.6 EB05 5.7 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious PRR 5.7	no trial data cached
Pulmonary hypertension	36	28.9 20.9–39.8ROR 29.7 · χ² 940 / p 1e-206	28.4 EB05 21.5 · IC025 +3.8 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious PRR 20.9	no trial data cached
Respiratory distress	35	21.2 15.3–29.4ROR 21.8 · χ² 655 / p 1e-144	21.0 EB05 15.8 · IC025 +3.5 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 15.0	no trial data cached
Oxygen saturation decreased	32	9.6 6.8–13.5ROR 9.8 · χ² 239 / p 4e-54	9.0 EB05 6.5 · IC025 +2.5 3/3 methods agree	Lab value / disease marker	serious PRR 7.4	no trial data cached
Hypoxia (low oxygen)	32	15.3 10.9–21.5ROR 15.7 · χ² 413 / p 4e-92	15.0 EB05 10.9 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 11.2 · 90% clinician	no trial data cached
Pulmonary arterial hypertension	23	26.5 17.6–39.7ROR 26.9 · χ² 538 / p 3e-119	25.9 EB05 18.2 · IC025 +3.4 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious PRR 19.5	no trial data cached
Fluid overload	22	25.0 16.5–37.8ROR 25.4 · χ² 482 / p 3e-107	24.5 EB05 17.0 · IC025 +3.3 3/3 methods agree	Not in label — unassessed	serious PRR 22.2	no trial data cached
Fluid retention	20	6.6 4.3–10.2ROR 6.7 · χ² 89 / p 2e-21	5.8 EB05 3.9 · IC025 +1.8 3/3 methods agree	Not in label — unassessed	serious PRR 5.3 · ♀ 75% (drug 49%)	no trial data cached
Viral infection	20	10.1 6.5–15.6ROR 10.2 · χ² 155 / p 8e-36	9.0 EB05 5.9 · IC025 +2.3 3/3 methods agree	Not in label — unassessed	serious PRR 9.1	no trial data cached
Acute respiratory failure	20	17.5 11.3–27.0ROR 17.8 · χ² 295 / p 2e-66	17.0 EB05 11.4 · IC025 +2.9 3/3 methods agree	Labeled (related wording) related wording	serious PRR 12.6 · 90% clinician	no trial data cached
Renal failure acute	18	7.0 4.4–11.1ROR 7.1 · χ² 87 / p 6e-21	6.1 EB05 4.0 · IC025 +1.8 3/3 methods agree	Likely indication confounding term in indications; also in warnings	serious PRR 5.1	no trial data cached
Anhedonia	16	10.1 6.2–16.5ROR 10.2 · χ² 123 / p 9e-29	8.8 EB05 5.4 · IC025 +2.1 3/3 methods agree	Not in label — unassessed	serious PRR 8.0	no trial data cached
Renal injury	15	8.4 5.1–13.8ROR 8.5 · χ² 90 / p 1e-21	7.1 EB05 4.4 · IC025 +1.9 3/3 methods agree	Not in label — unassessed	serious PRR 6.0	no trial data cached
Fear	15	9.3 5.6–15.3ROR 9.4 · χ² 103 / p 2e-24	7.9 EB05 4.8 · IC025 +2.0 3/3 methods agree	Not in label — unassessed	serious PRR 9.0	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.

Fluid overload — n=22, PRR 25.0
Hypoxia — n=32, PRR 15.3
Viral infection — n=20, PRR 10.1
Cardiac arrest — n=40, PRR 8.1
Fluid retention — n=20, PRR 6.6

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 Chlorothiazide?

In FDA FAERS, the most frequently co-reported reaction terms for Chlorothiazide are respiratory failure, cardiac arrest, pulmonary hypertension, respiratory distress, oxygen saturation decreased, hypoxia. 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 Chlorothiazide have an FDA boxed warning?

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

Do FAERS signals prove that Chlorothiazide 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 bd936e35-1af8-42da-bcc0-f22489d68574, effective 20211101; matched on openfda.generic_name.exact:"CHLOROTHIAZIDE")
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, 46 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.