Updated: January 25, 2026

What Is Spironolactone? Uses, Dosage, and What You Need to Know in 2026

Q: What is spironolactone used for in women?

In women, spironolactone is used for both its diuretic/cardiovascular effects and its anti-androgenic properties. FDA-approved uses include hypertension, heart failure, and edema. Off-label, it's commonly prescribed for hormonal acne, female pattern hair loss, hirsutism (excess hair growth), PCOS-related androgen symptoms, and gender-affirming hormone therapy in transgender women.

Q: Is spironolactone the same as Lasix (furosemide)?

No. Both are diuretics (water pills) but they work very differently. Lasix (furosemide) is a loop diuretic — it's more powerful and causes the kidneys to excrete large amounts of fluid and potassium. Spironolactone is a potassium-sparing diuretic — it's weaker but retains potassium. They are sometimes prescribed together to balance their effects.

Q: How long does it take for spironolactone to work?

For blood pressure and edema, noticeable effects can start within 1-2 weeks, but full effect may take 2-4 weeks. For acne and hair loss, results typically take 3-6 months of consistent use because these conditions involve slower biological cycles. Do not stop taking spironolactone early if you don't see immediate results for hormonal indications.

Q: Is spironolactone safe for long-term use?

Yes, spironolactone is generally considered safe for long-term use with appropriate monitoring. Your doctor will periodically check your kidney function and potassium levels (blood tests). The FDA boxed warning about tumorigenicity (based on animal studies) is noted on labeling, but decades of clinical use have not demonstrated a significant cancer risk in humans at therapeutic doses.

Q: Do I need to take spironolactone with food?

Spironolactone tablets can be taken with or without food. However, taking it consistently (either always with food or always without) is important because food significantly increases the absorption of spironolactone (by 22-95%). If you're taking the oral suspension (CaroSpir), your doctor will give specific instructions. Taking with food may also help reduce nausea if that's a concern.

Author

Peter Daggett

Summarize with AI

What Is Spironolactone?
What Conditions Does Spironolactone Treat?
FDA-Approved Indications
Common Off-Label Uses
Available Doses and Forms
Typical Doses by Indication
How to Take Spironolactone
Who Should NOT Take Spironolactone?
What Does It Cost?

Everything you need to know about spironolactone in 2026 — what it treats, how to take it, dosages, side effects, and who should not take it.

Spironolactone is one of the most versatile prescription medications in medicine. It's used by cardiologists for heart failure, dermatologists for acne, endocrinologists for hormonal disorders, and nephrologists for kidney and fluid conditions. Yet for many patients, it's a bit of a mystery. This guide gives you a complete, plain-English overview of what spironolactone is, what it does, and how to take it safely.

What Is Spironolactone?

Spironolactone is a prescription medication classified as a mineralocorticoid receptor antagonist (MRA) and potassium-sparing diuretic (water pill). It was originally developed in the 1950s to treat high blood pressure and fluid retention. Over time, doctors discovered it also blocks androgen (male sex hormone) receptors, making it useful for a wide range of hormonal conditions.

It is sold under the brand names

Aldactone (tablet form, now discontinued by Pfizer) and CaroSpir (oral suspension). Generic spironolactone tablets are widely available from multiple manufacturers.

What Conditions Does Spironolactone Treat?

Spironolactone has both FDA-approved indications and widely accepted off-label uses:

FDA-Approved Indications

Heart failure (NYHA Class III-IV): Reduces hospitalizations and improves survival in patients with reduced ejection fraction heart failure.

Hypertension: FDA-approved as add-on therapy for blood pressure not adequately controlled by other agents.

Primary hyperaldosteronism: Treats conditions where the adrenal glands produce too much aldosterone (e.g., Conn's syndrome).

Edema: Fluid retention associated with congestive heart failure, hepatic cirrhosis, and nephrotic syndrome.

Hypokalemia prevention: Prevents low potassium levels in patients requiring diuretic therapy.

Common Off-Label Uses

Hormonal acne in adult women: Widely used for persistent, late-onset, or cystic acne by reducing androgens that trigger oil production.

Female pattern hair loss (androgenic alopecia): Helps slow or reverse hair thinning in women by reducing androgen-driven hair follicle miniaturization.

Hirsutism (excess hair growth in women): Reduces unwanted facial and body hair by lowering androgen activity.

Gender-affirming hormone therapy: Used as an androgen blocker in transgender women as part of feminizing hormone therapy.

Polycystic ovary syndrome (PCOS): Reduces androgen-related symptoms (acne, irregular hair growth) associated with PCOS.

Available Doses and Forms

Spironolactone is available in the following forms:

Tablets: 25 mg, 50 mg, 100 mg (generic and brand; note Aldactone brand is discontinued)

Oral suspension: 25 mg/5 mL (CaroSpir brand — available but expensive and less common)

Typical Doses by Indication

Heart failure: 25 mg once daily; may increase to 50 mg once daily.

Hypertension: 25–100 mg daily in single or divided doses.

Primary hyperaldosteronism: 100–400 mg daily for diagnosis/management.

Edema: 100 mg daily, adjusted based on response.

Acne/hirsutism (off-label): 50–200 mg daily; most dermatologists start at 50 mg and titrate.

How to Take Spironolactone

Take at the same time each day, with or without food (but consistently — food affects absorption).

Taking in the morning may reduce nighttime urination.

Tablets and oral suspension are NOT interchangeable — they absorb differently. Use only the form your doctor prescribed.

Do not stop taking it suddenly without talking to your doctor, especially for heart or blood pressure indications.

Who Should NOT Take Spironolactone?

Patients with hyperkalemia (high potassium)

Patients with severe kidney disease (GFR <30 mL/min)

Patients with Addison's disease (primary adrenal insufficiency)

Pregnant women (risk of feminization of male fetus)

What Does It Cost?

Generic spironolactone is very affordable. With a GoodRx or SingleCare coupon, most patients pay $2–$5 for a 30-day supply of 25 mg tablets. Walmart offers it at approximately $6.89/month. Brand-name Aldactone has been discontinued, and the oral suspension (CaroSpir) is significantly more expensive.

If you're having trouble finding spironolactone at your pharmacy, medfinder calls pharmacies near you and texts you which ones have it in stock.

Frequently Asked Questions

In women, spironolactone is used for both its diuretic/cardiovascular effects and its anti-androgenic properties. FDA-approved uses include hypertension, heart failure, and edema. Off-label, it's commonly prescribed for hormonal acne, female pattern hair loss, hirsutism (excess hair growth), PCOS-related androgen symptoms, and gender-affirming hormone therapy in transgender women.

No. Both are diuretics (water pills) but they work very differently. Lasix (furosemide) is a loop diuretic — it's more powerful and causes the kidneys to excrete large amounts of fluid and potassium. Spironolactone is a potassium-sparing diuretic — it's weaker but retains potassium. They are sometimes prescribed together to balance their effects.

For blood pressure and edema, noticeable effects can start within 1-2 weeks, but full effect may take 2-4 weeks. For acne and hair loss, results typically take 3-6 months of consistent use because these conditions involve slower biological cycles. Do not stop taking spironolactone early if you don't see immediate results for hormonal indications.

Yes, spironolactone is generally considered safe for long-term use with appropriate monitoring. Your doctor will periodically check your kidney function and potassium levels (blood tests). The FDA boxed warning about tumorigenicity (based on animal studies) is noted on labeling, but decades of clinical use have not demonstrated a significant cancer risk in humans at therapeutic doses.

Spironolactone tablets can be taken with or without food. However, taking it consistently (either always with food or always without) is important because food significantly increases the absorption of spironolactone (by 22-95%). If you're taking the oral suspension (CaroSpir), your doctor will give specific instructions. Taking with food may also help reduce nausea if that's a concern.

Medfinder Editorial Standards

Medfinder's mission is to ensure every patient gets access to the medications they need. We are committed to providing trustworthy, evidence-based information to help you make informed health decisions.

Read our editorial standards