What the label lists and what reports show
Metolazone side effects
Metolazone's FDA label lists its adverse reactions in its own words. FAERS holds 11,175 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is dyspnoea (1,247 reports).
- Generic listed
Check it at the source: the metolazone FDA label on DailyMed (effective December 11, 2025, Unichem Pharmaceuticals (USA), Inc.); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsMetolazone tablets, USP, are usually well tolerated, and most reported adverse reactions have been mild and transient. Many of metolazone tablets, USP, related adverse reactions represent extensions of its expected pharmacologic activity and can be attributed to either its antihypertensive action or its renal/metabolic actions. The following adverse reactions have been reported. Several are single or comparably rare occurrences. Adverse reactions are listed in decreasing order of severity within body systems. Cardiovascular Chest pain/discomfort, orthostatic hypotension, excessive volume depletion, hemoconcentration, venous thrombosis, palpitations. Central And Peripheral Nervous System Syncope, neuropathy, vertigo, paresthesias, psychotic depression, impotence, dizziness/lightheadedness, drowsiness, fatigue, weakness, restlessness (sometimes resulting in insomnia), headache. …
Source: FDA drug label, Unichem Pharmaceuticals (USA), Inc., effective December 11, 2025 (SPL set c6fe5426-a184-44b8-a555-621d72aa5b9f), via openFDA; the full label on DailyMed
What do FAERS reports show?
11,175 reports list metolazone among the medicines taken, each a report of something that happened, not proof the medicine caused it; 2,203 are coded as a death and 5,777 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 23 reactions below, 8 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Metolazone: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions