Spironolactone

Spironolactone is approved for several conditions across its tablet and oral suspension formulations.

• Heart failure (NYHA Class III–IV): Spironolactone tablets and spironolactone oral suspension are both used to help patients with severe heart failure and reduced pumping function live longer, reduce fluid buildup, and stay out of the hospital. Usually given alongside other heart failure medicines.
• High blood pressure (hypertension): Both tablet and oral suspension forms are approved as add-on therapy for adults whose blood pressure isn't controlled on other medications alone. Lowering blood pressure reduces the risk of stroke and heart attack.
• Edema (fluid buildup) from liver cirrhosis: Both forms treat fluid buildup in adults with liver cirrhosis when cutting back on salt and fluids isn't enough.
• Edema from heart failure or nephrotic syndrome (tablets only): Spironolactone tablets (including Aldactone) are approved to manage edema in congestive heart failure and nephrotic syndrome when other treatments haven't provided enough relief.
• Primary hyperaldosteronism (tablets only): Aldactone and spironolactone tablets are used short-term before surgery to treat this adrenal gland disorder, and long-term for patients who are not surgical candidates or who have a type of adrenal gland overgrowth that doesn't require surgery.

Spironolactone works by blocking aldosterone — a hormone made by the adrenal glands that tells the kidneys to hold onto sodium (salt) and water while releasing potassium. By competing with aldosterone at its receptor in the kidney, spironolactone flips that equation: excess salt and water get flushed out in urine, while potassium is retained. This reduces fluid overload, lowers blood pressure, and eases the strain on the heart.

In conditions like heart failure, liver cirrhosis, and nephrotic syndrome, the body often overproduces aldosterone — making fluid buildup worse. Spironolactone counteracts this directly, which is why it's particularly useful in these settings.

Spironolactone is taken by mouth — as a tablet or oral suspension — typically once daily or in divided doses depending on the condition. The key rule for both forms: take it consistently with respect to food (always with food or always without), because food nearly doubles how much of the drug your body absorbs.

• Tablets (Aldactone and spironolactone tablets): taken once daily or in divided doses; edema treatment is usually started slowly in a hospital setting.
• Spironolactone oral suspension: dosed differently than tablets — it is not interchangeable with Aldactone; follow the suspension-specific instructions from your prescriber. Doses above 100 mg should use a different formulation.

Never adjust your dose on your own. Your prescriber will monitor your potassium and kidney function and fine-tune the dose based on your results.

The most commonly reported side effect of spironolactone is breast tissue enlargement in men (gynecomastia), but there are others to know about:

Seek medical attention right away if you notice signs of dangerously high potassium (muscle weakness, irregular heartbeat), severe skin reactions (blistering or peeling rash), signs of kidney failure (little to no urination), or symptoms of liver problems (confusion, yellowing skin). Rare but serious blood and liver reactions have also been reported.

• High potassium (hyperkalemia): This is the most serious risk — it can be fatal, especially in people with heart failure or kidney disease. Potassium and kidney labs must be checked within a week of starting and regularly thereafter. Avoid potassium supplements and potassium-containing salt substitutes unless directed.
• Low blood pressure and worsening kidney function: Too much fluid loss can cause dehydration, dizziness, and kidney stress — especially in people on ACE inhibitors or ARBs. Report symptoms like lightheadedness or decreased urination promptly.
• Electrolyte imbalances: Spironolactone can lower sodium, magnesium, and calcium, and can raise uric acid and blood sugar. Regular monitoring is needed.
• Liver disease: In patients with cirrhosis, sudden fluid or electrolyte shifts can trigger confusion or coma. Treatment should be started in a hospital for these patients, and doses should be increased very slowly.
• Tumor risk in animals (boxed warning): Long-term high-dose use caused tumors in rats. Use only for approved indications — unnecessary use should be avoided.

Spironolactone has several important drug and food interactions — mostly centered around potassium levels and kidney function:

• Potassium supplements, high-potassium foods, and potassium-based salt substitutes: Can push potassium to dangerous levels when combined with spironolactone.
• ACE inhibitors and ARBs (e.g., lisinopril, losartan): Both raise potassium — combining with spironolactone significantly increases hyperkalemia risk; close monitoring required.
• NSAIDs (e.g., ibuprofen, naproxen): Can reduce spironolactone's diuretic and blood pressure effects and increase kidney stress.
• Lithium: Spironolactone slows the kidney's clearance of lithium, raising the risk of lithium toxicity; levels should be monitored.
• Aspirin (acetylsalicylic acid): May reduce spironolactone's effectiveness — your prescriber may need to adjust your dose.
• Cholestyramine: Combined use has been linked to a dangerous acid imbalance in the blood.
• Digoxin: Spironolactone interferes with certain lab tests that measure digoxin — make sure your lab uses an assay that doesn't interact with spironolactone.
• Abiraterone: Combination is not recommended — may affect PSA (prostate cancer marker) test results.
• Mitotane: Avoid combining — spironolactone significantly reduces mitotane blood levels, reducing its effectiveness.

Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.

• Do not take spironolactone if you currently have high potassium levels (hyperkalemia), Addison's disease (adrenal gland insufficiency), or are taking eplerenone — these are absolute contraindications.
• Kidney disease: Spironolactone is cleared through the kidneys; impaired kidney function increases the risk of dangerous potassium buildup. Closer monitoring and possibly lower doses are needed.
• Liver disease (cirrhosis): Fluid and electrolyte changes from this drug can worsen liver encephalopathy (brain function impairment). These patients should begin treatment in a hospital at the lowest possible dose.
• Pregnancy: Spironolactone may affect the sexual development of a male fetus. Pregnant women or those who may become pregnant should discuss the risks with their doctor before taking this medication.
• Breastfeeding: An active metabolite (canrenone) has been found in breast milk in small amounts. Discuss with your doctor whether to continue breastfeeding.
• Children: Safety and effectiveness in pediatric patients have not been established.
• Older adults: Decreased kidney function with age raises the risk of side effects — kidney function should be monitored closely.

Taking too much spironolactone may cause drowsiness, confusion, nausea, vomiting, dizziness, diarrhea, or a skin rash. In people with impaired kidney or liver function, dangerous high potassium or low sodium levels may develop. There is no specific antidote — treatment focuses on supportive care, maintaining hydration and electrolyte balance. If you think you or someone else has taken too much, seek emergency medical help immediately.

Spironolactone works by blocking aldosterone receptors in the kidneys, causing the body to excrete extra sodium and water in the urine while retaining potassium. This results in reduced fluid overload (edema), lower blood volume, and lower blood pressure. In conditions like heart failure, cirrhosis, and nephrotic syndrome — where the body produces excess aldosterone in response to fluid shifts — spironolactone directly counters that hormonal signal to relieve fluid buildup.

After an oral dose, spironolactone reaches peak blood levels in about 2.6 hours on average, though its active metabolite canrenone peaks later (around 4.3 hours). Food nearly doubles the amount of drug absorbed, which is why consistent habits around meals matter. Spironolactone itself is broken down quickly (half-life of about 1.4 hours), but its active metabolites last much longer — canrenone, for example, has a half-life of about 16.5 hours — meaning the drug's effects persist well beyond the initial dose. Metabolites are eliminated mainly through the urine, and clearance is slowed in patients with liver cirrhosis.

Store below 77°F (25°C).