Two medicines, side by side
Metolazone vs spironolactone
Metolazone and spironolactone are both labeled for high blood pressure, heart failure and edema (fluid retention). Drugs@FDA records approvals of metolazone since 1973 and of spironolactone since 1960. Pharmacies paid $0.233 per metolazone 2.5 mg tablet and $0.0426 per spironolactone 25 mg tablet (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. In FDA's classes, metolazone is a thiazide-like diuretic and spironolactone an aldosterone antagonist.
Check it at the source: the metolazone FDA label on DailyMed (effective December 11, 2025); the spironolactone FDA label on DailyMed (effective November 28, 2025).
Highlights of the metolazone record
Metolazone (Zaroxolyn) · label of December 11, 2025
Used for
From the label: indicationsMetolazone tablets, USP, are indicated for the treatment of salt and water retention including: edema accompanying congestive heart failure; edema accompanying renal diseases, including the nephrotic syndrome and states of diminished renal function. Metolazone tablets, USP, are also indicated for the treatment of hypertension, alone or in combination with other antihypertensive drugs of a different class. […]
On the market
- Earliest approval on file
- November 27, 1973
- Generic labelers
- 19 labelers
- Pharmacy cost
- $0.233 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 0
Highlights of the spironolactone record
Spironolactone (Aldactone) · label of November 28, 2025
Used for
From the label: indicationsALDACTONE is an aldosterone antagonist indicated for: • The treatment of NYHA Class III–IV heart failure and reduced ejection fraction to increase survival, manage edema, and to reduce the need for hospitalization for heart failure ( 1.1 ). • Use as an add-on therapy for the treatment of hypertension, to lower blood pressure. […]
On the market
- Earliest approval on file
- January 21, 1960
- Generic labelers
- 38 labelers
- Pharmacy cost
- $0.0426 per tablet
Supply and safety
- Shortage
- A presentation being discontinued
- Recalls
- 6
Source: FDA drug labels via openFDA (Metolazone label of December 11, 2025, Spironolactone label of November 28, 2025); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do metolazone and spironolactone differ on the record?
In FDA's classes, metolazone is a thiazide-like diuretic and spironolactone an aldosterone antagonist.
Generics: metolazone since 2003; spironolactone since 1980 (Drugs@FDA).
| Metolazone | Spironolactone | |
|---|---|---|
| Labeled for | High blood pressure, Edema (fluid retention), Heart failure | Heart failure, Edema (fluid retention), High blood pressure |
| Pharmacologic class | Thiazide-like Diuretic | Aldosterone Antagonist |
| How it works (label) | n/a | Spironolactone and its active metabolites are specific pharmacologic antagonists of aldosterone, acting primarily through competitive binding of receptors at the aldosterone-dependent sodium-potassium exchange site in the distal convoluted … |
| Half-life (label) | n/a | The mean half-life values of its metabolites including canrenone, 7-α-(thiomethyl) spirolactone (TMS), and 6-β-hydroxy-7-α-(thiomethyl) spirolactone (HTMS) are 16.5, 13.8, and 15 hours, respectively. |
| Earliest approval on file (Drugs@FDA) | November 27, 1973 | January 21, 1960 |
| First generic approved | December 19, 2003 | May 7, 1980 |
| Generic labelers (NDC) | 19 labelers | 38 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.233 per tablet (Metolazone 2.5 mg tablet) | $0.0426 per tablet (Spironolactone 25 mg tablet) |
| 12-month price change | +8% | -14% |
| Boxed warning | No | No |
| Shortage now | No current entry | A presentation being discontinued |
| Recalls recorded | 0 | 6 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 11,175 | 139,757 |
| DEA schedule | none | none |
Source: Drugs@FDA, FDA NDC Directory, CMS NADAC of October 7, 2026, FDA shortages and recalls, FAERS via openFDA (FDA files October 8, 2026)
What next?
- Alternatives to metolazone
- every medicine labeled for the same conditions