Hair lossActive ingredient
Spironolactone
Aldosterone antagonist and potassium-sparing diuretic1 FDA label read
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.
Highlights of the labels
- Aldactone
- Heart failure, hypertension, oedema, hyperaldosteronismnot hair loss
- Supply
- Prescription only
- Generic
- 14 approved applications
- Boxed warning
- None in these labels
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 | What its label approves | Supply | Label version |
|---|---|---|---|
| AldactonePfizer Laboratories Div Pfizer Inc | What its label approvesHeart failure, hypertension, oedema, hyperaldosteronismNot hair loss | SupplyPrescription | Label version28 November 2025 |
How it works
The spironolactone label is a document about the kidney, blood pressure and potassium, and the quotation below is how it describes the medicine. Hair is not mentioned anywhere in it. That absence is the whole reason this page is worded as it is: the medication appears in hair loss discussions, and the approval it holds is for something else entirely.
Mechanism of action, 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. Spironolactone acts both as a diuretic and as an antihypertensive drug by this mechanism.
What the FDA approved it for
The approved uses, as worded in the 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.
- 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.
- 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.
most common adverse reaction with ALDACTONE treatment is gynecomastia.
Warnings and precautions
The warnings and precautions section of the 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.
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.
- 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.
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
Generic spironolactone is approved and widely available.
The FDA label database lists 14 approved generic applications for this ingredient.
What affects the cost
Spironolactone is an old generic medicine and inexpensive. Its label does not cover hair loss. This site sells nothing and links to no sellers.
What pharmacies pay for it
These are acquisition costs: what pharmacies in the United States pay on average to buy the medication, published weekly by the Centers for Medicare and Medicaid Services. They are not retail prices and not what a person pays at the counter, which depends on insurance, pharmacy and discount programmes. They are useful as an objective floor and for seeing how far a brand sits above its generic.
| Measured | Generic |
|---|---|
| per tablet, capsule or pen | Generic$0.089 (range $0.043 to $0.188, 2439 listings) |
| per millilitre | Generic$1.73 (range $1.53 to $2.03, 180 listings) |
Median of 2619 listings. Effective dates 2025-12-17 to 2026-07-22, file dated 2026-07-29.
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.
- What is Aldactone?
- Aldactone is the brand name under which spironolactone is sold, and it is the label this page is built from. That label calls it an aldosterone antagonist and approves it for heart failure with reduced ejection fraction, hypertension as add-on therapy, oedema and primary hyperaldosteronism. Its mechanism section states that sodium and water are excreted while potassium is retained, and that it acts as both a diuretic and an antihypertensive. Generic spironolactone is the same active ingredient.
- Is spironolactone a steroid?
- The label does not use that word to describe the medicine. It calls spironolactone an aldosterone antagonist, and its description section gives the chemical name in full rather than a class of that kind. What people usually mean by the question is whether it is an anabolic steroid or a corticosteroid, and the label draws no comparison with either.
- 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.
Each stripe is one section of the label, each division in a stripe one entry in that section.
Page last updated 18 August 2026
Compiled by the HealthyStudy editorial team from FDA source documents. No medical reviewer is credited on this page, because none reviewed it.