Last reviewed 2026-04-20 · How we verify

Aldactone (spironolactone)

Potassium-sparing diuretic and mineralocorticoid receptor antagonist that blocks aldosterone, reducing fluid retention and lowering blood pressure.

Spironolactone (Aldactone) is a mineralocorticoid antagonist approved in 1960. Proven to reduce mortality in heart failure (RALES trial). Also widely used off-label for hormonal acne. Available generically.

At a glance

Mechanism of action

Spironolactone competitively blocks aldosterone at the mineralocorticoid receptor, reducing sodium reabsorption and potassium excretion. The RALES trial proved it reduces mortality in heart failure by 30%. Its anti-androgen properties make it widely used off-label for hormonal acne, hirsutism, and as part of feminizing hormone therapy. Hyperkalemia is the main safety concern.

Approved indications

• Aldosteronism
• Ascites
• Chronic heart failure
• Diagnostic Test for Primary Aldosteronism
• Edema
• Edema due to Hepatic Cirrhosis
• Edema due to Nephrotic Syndrome
• Hypertensive disorder
• Hypokalemia Prevention
• Peripheral Edema due to Chronic Heart Failure
• Pulmonary Edema due to Chronic Heart Failure

Common side effects

• Gynecomastia
• Hyperkalemia
• Dizziness
• Headache
• Nausea
• Diarrhea
• Vomiting
• Drowsiness
• Leg cramps
• Lethargy
• Mental confusion
• Ataxia

Serious adverse events

• Hyperkalemia
• Renal dysfunction/renal failure
• Stevens-Johnson Syndrome (SJS)
• Toxic epidermal necrolysis (TEN)
• Drug rash with eosinophilia and systemic symptoms (DRESS)
• Hepatocellular toxicity
• Anaphylactic reactions
• Leukopenia/agranulocytosis
• Thrombocytopenia
• Gastric bleeding

Key clinical trials

• The Effects of Losartan and Spironolactone on Residual Renal Function Preservation in Peritoneal Dialysis Patients (NA)
• Bioavailability and Bioequivalence (BA/BE) Study of Extended Release (ER) Torsemide and Spironolactone Fixed Dose Combination (FDC) Tablet in Healthy Adult Human Subjects (Phase 3)
• Early Symptom Control and Palliative Care Referral for Advanced Hepatocellular Carcinoma; a Randomized Control Trial (NA)
• Effects of Dapagliflozin on Hypotensive Patients With Depressed Left Ventricular Ejection Fraction After Sacubitril/Valsartan Therapy (Phase 4)
• NCT01687699 (Phase 4)
• A Single-Center, Prospective Randomized, Double-Masked, Placebo-Controlled, Parallel- Group Pilot Study of the Effects and Safety of Topical Spironolactone Ophthalmic Solution, 0.005 mg/cc in Subjects (EARLY/Phase 1)
• Matão Controlling Hypertension (MatCH Study): Rationale and Design. Project to Reduce Incidence of Arterial Hypertension in City of Matão, Brazil. (EARLY/Phase 1)
• "An Open-label Clinical Trial to Evaluate the Safety and Efficacy of Empagliflozin and Sacubitril/Valsartan in Adult Patients With Chronic Heart Failure With Reduced Ejection Fraction Associated With (Phase 2)

Patents

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.