metolazone Side Effects
Also known as: Zaroxolyn
Analysis of 10,872 adverse event reports submitted to the FDA from 2003 to 2025.
Total Reports
10,872
Death-Related
2,165
19.9% of reports
Hospitalizations
5,657
52.0% of reports
Top Indication
Product Used For Unknown Indication
Most Reported Adverse Reactions
Who Reports Side Effects
Gender Distribution
Age Distribution
Reporting Trend by Year
Reactions in Death Reports
Top reactions reported in 2,165 reports where death was an outcome. These are voluntarily reported and do not establish causation.
| Reaction | Reports |
|---|---|
| DEATH | 866 |
| DYSPNOEA | 273 |
| RENAL FAILURE | 228 |
| CARDIAC FAILURE CONGESTIVE | 227 |
| ACUTE KIDNEY INJURY | 201 |
| HYPOTENSION | 160 |
| CHRONIC KIDNEY DISEASE | 151 |
| CARDIAC FAILURE | 134 |
| NAUSEA | 134 |
| ASTHENIA | 127 |
| CARDIAC ARREST | 124 |
| PNEUMONIA | 123 |
| RESPIRATORY FAILURE | 118 |
| ATRIAL FIBRILLATION | 112 |
| OEDEMA PERIPHERAL | 112 |
| CONDITION AGGRAVATED | 111 |
| END STAGE RENAL DISEASE | 110 |
| DIARRHOEA | 106 |
| FATIGUE | 99 |
| SEPSIS | 98 |
Reactions in Hospitalization Reports
Top reactions in 5,657 reports where hospitalization was an outcome.
| Reaction | Reports |
|---|---|
| DYSPNOEA | 856 |
| CARDIAC FAILURE CONGESTIVE | 571 |
| ACUTE KIDNEY INJURY | 505 |
| PNEUMONIA | 444 |
| HYPOTENSION | 442 |
| NAUSEA | 436 |
| ASTHENIA | 413 |
| FALL | 398 |
| RENAL FAILURE | 391 |
| FATIGUE | 377 |
| OEDEMA PERIPHERAL | 374 |
| FLUID RETENTION | 370 |
| DIARRHOEA | 367 |
| DIZZINESS | 361 |
| ANAEMIA | 314 |
| DEHYDRATION | 307 |
| GASTROINTESTINAL HAEMORRHAGE | 296 |
| CARDIAC FAILURE | 292 |
| ATRIAL FIBRILLATION | 272 |
| VOMITING | 269 |
Nearby — Related Medications
What the FAERS Data Reveals About metolazone Side Effects
The FDA Adverse Event Reporting System (FAERS) contains 10,872 voluntary reports linked to metolazone and its brand equivalents (Zaroxolyn), spanning 2003 through 2025. Of those, 2,165 (19.9%) listed death as an outcome and 5,657 (52.0%) involved hospitalization. The most common indication reported alongside adverse events was Product Used For Unknown Indication.
Demographic breakdowns help contextualize who is being exposed to the drug. Of reports with known sex, 52% were female and 47% male; age distribution skews toward 45-64, with 2,672 reports in that bracket. The single most reported reaction is dyspnoea with 1,204 submissions, followed by death and acute kidney injury.
FAERS is a signal-detection tool, not a scorecard. Reports are voluntary, and a single case may list multiple suspect drugs, so numbers above should not be read as incidence rates or per-patient risk. Widely prescribed drugs naturally accumulate more reports than niche therapies even when individual risk is low. These aggregates are useful for spotting patterns that merit further pharmacovigilance, not for choosing between medications. This page is for educational reference only and is not medical advice — speak with a licensed clinician about any side-effect concerns.
Read our methodology — how this data is sourced, computed, and verified.