Spironolactone
Aldosterone antagonist and potassium-sparing diuretic. Sold as Aldactone.
Spironolactone is a diuretic with anti-androgen activity, approved for cardiovascular and endocrine conditions. It is discussed in connection with female pattern hair loss because of that anti-androgen effect, but no such indication appears in its FDA label.
Brands and what each one is approved for
One active ingredient can hold several separate FDA approvals. They are different documents with different approved uses, and mixing them up is the most common mistake made about these medications.
| Brand | Status for this use | Supply | Label version |
|---|---|---|---|
| AldactonePfizer Laboratories Div Pfizer Inc | Approved for another condition | Prescription | 28 November 2025 |
How it works
Written by us
The label describes spironolactone as a specific antagonist of aldosterone, acting mainly through competitive binding of receptors in the distal tubule of the kidney. The label does not describe an effect on hair.
From the mechanism of action section of the Aldactone label
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 renal tubule. Spironolactone causes increased amounts of sodium and water to be excreted, while potassium is retained.
What the FDA approved it for
The approved uses, as worded in the label.
From the FDA label
- 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.
- Use as an add-on therapy for the treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions.
- The management of edema in adult patients who are cirrhotic when edema is not responsive to fluid and sodium restrictions and in the setting of nephrotic syndrome when treatment of the underlying disease, restriction of fluid and sodium intake, and the use of other diuretics produce an inadequate response.
- Treatment of primary hyperaldosternism for: Short-term preoperative treatment; Long-term maintenance for patients with discrete aldosterone-producing adrenal adenomas who are not candidates for surgery and patients with bilateral micro or macronodular adrenal hyperplasia Heart Failure ALDACTONE is indicated for treatment of NYHA Class III-IV heart failure and reduced ejection fraction to increase...
Forms and strengths
The presentations and strengths listed in the label.
From the FDA label
- Tablets: 25 mg round, light yellow, film-coated, with SEARLE and 1001 debossed on one side and ALDACTONE and 25 on the other side.
- Tablets: 50 mg oval, light orange, scored, film-coated, with SEARLE and 1041 debossed on the scored side and ALDACTONE and 50 on the other side.
- Tablets: 100 mg round, peach-colored, scored, film-coated, with SEARLE and 1031 debossed on the scored side and ALDACTONE and 100 on the other side.
- Tablets: 25 mg, 50 mg, and 100 mg
How the label says it is taken
What the label states about administration. It is not a dosing instruction for any individual.
From the FDA label
- Heart Failure: Initiate treatment at 25 mg once daily.
- Hypertension: Initiate treatment at 25 to 100 mg daily in either single or divided doses.
- Edema: Initiate therapy in a hospital setting and titrate slowly. The recommended initial daily dose is 100 mg in single or divided doses.
- Primary hyperaldosteronism: Initiate treatment at 100 to 400 mg in preparation for surgery. In patients unsuitable for surgery use the lowest effective dosage determined for the individual patient. General Considerations ALDACTONE can be taken with or without food, but should be taken consistently with respect to food.
Most common adverse reactions
The adverse reactions the label reports as most common.
From the FDA label
most common adverse reaction with ALDACTONE treatment is gynecomastia.
Warnings and precautions
The warnings and precautions section of the label.
From the FDA label
- Hyperkalemia: Monitor serum potassium within one week of initiation and regularly thereafter.
- Hypotension and Worsening Renal Function: Monitor volume status and renal function periodically.
- Electrolyte and Metabolic Abnormalities: Monitor serum electrolytes, uric acid and blood glucose periodically.
- Gynecomastia: ALDACTONE can cause gynecomastia. Hyperkalemia ALDACTONE can cause hyperkalemia. This risk is increased by impaired renal function or concomitant potassium supplementation, potassium-containing salt substitutes or drugs that increase potassium, such as angiotensin converting enzyme inhibitors and angiotensin receptor blockers.
Contraindications
Situations in which the label states the medication must not be used.
From the FDA label
Concomitant use of eplerenone ALDACTONE is contraindicated in patients with: ▪ Hyperkalemia ▪ Addison's disease ▪ Concomitant use of eplerenone
Drug interactions
Interactions the label singles out.
From the FDA label
- Agents increasing serum potassium: Concomitant administration can lead to hyperkalemia.
- Lithium: Increased risk of lithium toxicity.
- NSAIDs: May reduce the diuretic, natriuretic and antihypertensive effect of ALDACTONE.
- Digoxin: ALDACTONE can interfere with radioimmunologic assays of digoxin exposure.
- Cholestyramine: Hyperkalemic metabolic acidosis has been reported with concomitant use.
- Acetylsalicylic Acid (ASA): ASA may reduce the efficacy of ALDACTONE.
Pregnancy and breastfeeding
The opening of the pregnancy section of the label. The full section is longer and is in the source document.
From the FDA label
Based on mechanism of action and findings in animal studies, spironolactone may affect sex differentiation of the male during embryogenesis (see Data). Rat embryofetal studies report feminization of male fetuses and endocrine dysfunction in females exposed to spironolactone in utero. Limited available data from published case reports and case series did not demonstrate an association of major malformations or other adverse pregnancy outcomes with spironolactone.
Generic or brand
Written by us
Generic spironolactone is approved and widely available.
The FDA label database lists 14 approved generic applications for this ingredient.
What affects the cost
Written by us
Spironolactone is an old generic medicine and inexpensive. Its label does not cover hair loss. This site does not track prices and does not link to sellers.
Common questions
- Is spironolactone approved for hair loss?
- No. The FDA label lists heart failure, hypertension, oedema and primary hyperaldosteronism. Hair loss is not among them, and this page does not describe what use for hair loss would involve.
- Why is it associated with hair loss treatment at all?
- Because it has anti-androgen activity in addition to its diuretic action, and androgens are involved in pattern hair loss. That is a pharmacological connection, not a regulatory approval.
Other medications under hair loss
Whether each one carries an FDA approval for this use is marked on its page and in this list.
Sources
Every fact above comes from one of these documents. The date is the effective date of the label version this page was built from.
FDA prescribing information for Aldactone
Pfizer Laboratories Div Pfizer Inc. Label version 25, effective 28 November 2025.
Page last updated: 29 July 2026
Compiled by the HealthyStudy editorial team from FDA source documents. No medical reviewer is credited on this page, because none reviewed it.