Metolazone: adverse event reports filed with FDA

1,352

reports as suspect product

0% of all reports · about 60 a year

58

reports, 12 months to June 2026

43 in the 12 months before

88.7%

marked serious by the reporter

90% across the class

18.3%

record death among outcomes, as reported

248 reports · not verified by FDA

Reports by month, five years

Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.

By year received

2026 covers reports received through June 2026 only.

Reactions recorded in the reports

share of Metolazone reports recording the termmedian drug in thiazide-like diuretic

1. Acute kidney injurysudden loss of kidney function10.6%143
2. Hypokalaemialow blood potassium10.6%143
3. Dyspnoeashortness of breath8.4%113
4. Hypotensionlow blood pressure8.3%112
5. Renal failure acute7.4%100
6. Nauseafeeling sick7.3%99
7. Dehydrationdehydration7.2%98
8. Hyponatraemialow blood sodium7.2%97
9. Dizzinesslight-headedness or unsteadiness6.8%92
10. Condition aggravatedthe condition being treated got worse6.2%84
11. Astheniaweakness or lack of energy6.1%83
12. Blood creatinine increasedraised creatinine, a kidney test5.6%76
13. Cardiac failureheart failure5.6%76
14. Drug ineffectivethe medicine did not work as expected5.3%72
15. Diarrhoealoose or frequent stools4.7%63
16. Drug interactionan interaction between medicines4.7%63
17. Syncopefainting4.6%62
18. Weight decreasedweight loss4.5%61
19. Falla fall4.1%56
20. Fatiguetiredness4.1%55
21. Toxicity to various agentspoisoning or toxic effect of one or more substances4.1%55
22. Cardiac failure congestivecongestive heart failure3.6%49
23. Headachehead pain3.6%49
24. Completed suicidedeath by suicide3.3%44
25. Oedema peripheralswelling of the legs, ankles or hands3.3%44
26. Renal impairmentreduced kidney function3.3%44
27. Blood potassium decreased3%41
28. Fluid retentionthe body holding extra fluid3%40
29. Electrocardiogram QT prolongeda QT prolongation on the ECG2.9%39
30. Malaisegeneral feeling of being unwell2.9%39

Top 30 of 433 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 4 drugs in the thiazide-like diuretic class; it describes the reports, not the patients. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Outcomes recorded

Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 9,368 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."

Patients and reporters

Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 66.6% of reports give the United States as the country of the event or reporter.

Reason for use recorded

The indication field is filled in by the reporter and is often blank; shares are of all 1,352 reports.

Drugs most often listed in the same reports

Other products listed in reports where Metolazone is a suspect product, whatever their own role. Co-listing means the two were recorded together; it says nothing about either product's part in the event. Only the 2,500 most-reported names are counted here.

In context

Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Other drugs in the thiazide-like diuretic class

Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." A brand and its generic are separate rows because reporters name them separately.

Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A report counts here when it lists Metolazone as a suspect or interacting product; reports listing it only as a concomitant medication (9,920) are excluded. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.