Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
Quick facts
- Drug class
- Aldosterone Antagonist [EPC], Aldosterone Antagonists [MoA]
- How it is given
- oral
- Type
- human prescription drug
- RxNorm ID
- 198222
We do not publish dosing. How much of this medicine to take, how often, and for how long depends on your age, weight, kidney and liver function, other conditions and other medicines. That is a decision for the person who prescribes or dispenses it. Follow the directions on your own pack and ask your pharmacist if anything is unclear.
What it is used to treat
Spironolactone is an aldosterone antagonist indicated for: 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 ( 1.1 ). 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 ( 1.2 ). 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 ( 1.3 ). Treatment of primary hyperaldosteronism for: ( 1.4 ) 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 1.1 Heart Failure Spironolactone is indicated for treatment of NYHA Class III-IV heart failure and reduced ejection fraction to increase survival, manage edema, and reduce the need for hospitalization for heart failure. Spironolactone is usually administered in conjunction with other heart failure therapies. 1.2 Hypertension Spironolactone is indicated as add-on therapy for the treatment of hypertension, to lower blood pressure in patients who are not adequately controlled on other agents. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. These benefits have been seen in controlled trials of antihypertensive drugs from a wide variety of pharmacologic classes. Control of high blood pressure should be part of comprehensive cardiovascular risk management, including, as appropriate, lipid control, diabetes management, antithrombotic therapy, smoking cessation, exercise, and limited sodium intake. Many patients will require more than one drug to achieve blood pressure goals. […]
About this medicine
Spironolactone oral tablets contain 25 mg, 50 mg, or 100 mg of the aldosterone antagonist spironolactone, 17 hydroxy-7α-mercapto-3-oxo-17α-pregn-4-ene-21-carboxylic acid γ-lactone acetate, which has the following structural formula: Spironolactone is practically insoluble in water, soluble in alcohol, and freely soluble in benzene and in chloroform. Inactive ingredients include calcium sulfate, hypromellose, magnesium stearate, microcrystalline cellulose, N & A mint flavor, polyethylene glycol, povidone, pregelatinized corn starch, sodium starch glycolate, talc, and titanium dioxide 20
How it works
12.1 Mechanism of Action 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. It may be given alone or with other diuretic agents that act more proximally in the renal tubule.
Who should not take it
Spironolactone is contraindicated in the patients with: Hyperkalemia Addison’s disease Concomitant use of eplerenone Spironolactone is contraindicated in patients with ( 4 ): Hyperkalemia Addison’s disease Concomitant use of eplerenone
Warnings and cautions
Hyperkalemia: Monitor serum potassium within one week of initiation and regularly thereafter ( 5.1 ). Hypotension and Worsening Renal Function: Monitor volume status and renal function periodically ( 5.2 ). Electrolyte and Metabolic Abnormalities: Monitor serum electrolytes, uric acid and blood glucose periodically ( 5.3 ). Gynecomastia: Spironolactone can cause gynecomastia ( 5.4 ). 5.1 Hyperkalemia Spironolactone 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 [see Drug Interactions (7.1) ] . Monitor serum potassium within 1 week of initiation or titration of spironolactone and regularly thereafter. More frequent monitoring may be needed when spironolactone is given with other drugs that cause hyperkalemia or in patients with impaired renal function. If hyperkalemia occurs, decrease the dose or discontinue spironolactone and treat hyperkalemia. 5.2 Hypotension and Worsening Renal Function Excessive diuresis may cause symptomatic dehydration, hypotension and worsening renal function, particularly in salt-depleted patients or those taking angiotensin converting enzyme inhibitors and angiotensin II receptor blockers. Worsening of renal function can also occur with concomitant use of nephrotoxic drugs (e.g., aminoglycosides, cisplatin, and NSAIDs). Monitor volume status and renal function periodically. 5.3 Electrolyte and Metabolic Abnormalities In addition to causing hyperkalemia, spironolactone can cause hyponatremia, hypomagnesemia, hypocalcemia, hypochloremic alkalosis, and hyperglycemia. Asymptomatic hyperuricemia can occur and rarely gout is precipitated. Monitor serum electrolytes, uric acid and blood glucose periodically. 5.4 Gynecomastia Spironolactone can cause gynecomastia. In Randomized Spironolactone Evaluation Study, patients with heart failure treated with a mean dose of 26 mg of spironolactone once daily, about 9% of the male subjects developed gynecomastia. […]
Reported side effects
The following clinically significant adverse reactions are described elsewhere in the labeling: Hyperkalemia [see Warnings and Precautions (5.1) ] Hypotension and Worsening Renal Function [see Warnings and Precautions (5.2) ] Electrolyte and Metabolic Abnormalities [see Warnings and Precautions (5.3) ] Gynecomastia [see Warnings and Precautions (5.4) ] Impaired neurological function/ coma in patients with hepatic impairment, cirrhosis and ascites [see Use in Specific Populations (8.7) ] The following adverse reactions associated with the use of spironolactone were identified in clinical trials or postmarketing reports. Because these reactions were reported voluntarily from a population of uncertain size, it is not always possible to estimate their frequency, reliably, or to establish a causal relationship to drug exposure. Digestive: Gastric bleeding, ulceration, gastritis, diarrhea and cramping, nausea, vomiting. Reproductive: Decreased libido, inability to achieve or maintain erection, irregular menses or amenorrhea, postmenopausal bleeding, breast and nipple pain. Hematologic: Leukopenia (including agranulocytosis), thrombocytopenia. Hypersensitivity: Fever, urticaria, maculopapular or erythematous cutaneous eruptions, anaphylactic reactions, vasculitis. Metabolism: Hyperkalemia, electrolyte disturbances [see Warnings and Precautions (5.1 , 5.3) ] , hyponatremia, hypovolemia. Musculoskeletal : Leg cramps. Nervous system/psychiatric: Lethargy, mental confusion, ataxia, dizziness, headache, drowsiness. Liver/biliary: A very few cases of mixed cholestatic/hepatocellular toxicity, with one reported fatality, have been reported with spironolactone administration. Renal: Renal dysfunction (including renal failure). Skin: Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN), drug rash with eosinophilia and systemic symptoms (DRESS), alopecia, pruritis. The most common adverse reaction with spironolactone treatment is gynecomastia ( 5.4 , 6 ). To report SUSPECTED ADVERSE REACTIONS, contact Oxford, at 1-844-508-1455, 8:00 am – 4:30 ET, Monday – Friday or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
Interactions with other medicines
Agents increasing serum potassium: Concomitant administration can lead to hyperkalemia ( 5.1 , 7.1 ). Lithium: Increased risk of lithium toxicity ( 7.2 ). NSAIDs: May reduce the diuretic, natriuretic and antihypertensive effect of spironolactone ( 7.3 ). Digoxin: spironolactone can interfere with radioimmunologic assays of digoxin exposure ( 7.4) . Cholestyramine: Hyperkalemic metabolic acidosis has been reported with concomitant use ( 7.5 ). Acetylsalicylic Acid (ASA): ASA may reduce the efficacy of spironolactone ( 7.6 ) Abiraterone: May increase prostate-specific antigen (PSA) levels ( 7.7 ). 7.1 Drugs and Supplements Increasing Serum Potassium Concomitant administration of spironolactone with potassium supplementation or drugs that can increase potassium may lead to severe hyperkalemia. In general, discontinue potassium supplementation in heart failure patients who start spironolactone [see Warnings and Precautions (5.1) and Clinical Pharmacology (12.3) ] . Check serum potassium levels when ACE inhibitor or ARB therapy is altered in patients receiving spironolactone. Examples of drugs that can increase potassium include: ACE inhibitors angiotensin receptor blockers non-steroidal anti-inflammatory drugs (NSAIDs) heparin and low molecular weight heparin trimethoprim 7.2 Lithium Like other diuretics, spironolactone reduces the renal clearance of lithium, thus increasing the risk of lithium toxicity. Monitor lithium levels periodically when spironolactone is coadministered [see Clinical Pharmacology (12.3) ] . 7.3 Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) In some patients, the administration of an NSAID can reduce the diuretic, natriuretic, and antihypertensive effect of diuretics. Therefore, when spironolactone and NSAIDs are used concomitantly, monitor closely to determine if the desired effect of the diuretic is obtained [see Clinical Pharmacology (12.3) ] . 7.4 Digoxin Spironolactone and its metabolites interfere with radioimmunoassays for digoxin and increase the apparent exposure to digoxin. It is unknown to what extent, if any, spironolactone may increase actual digoxin exposure. […]
Use in specific groups
Pregnancy: Based on animal data, spironolactone may affect sex differentiation of the male during embryogenesis ( 8.1 ). 8.1 Pregnancy Risk Summary 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 . There are risks to the mother and fetus associated with heart failure, cirrhosis and poorly controlled hypertension during pregnancy [see Clinical Considerations ] . Because of the potential risk to the male fetus due to anti-androgenic properties of spironolactone and animal data, avoid spironolactone in pregnant women or advise a pregnant woman of the potential risk to a male fetus. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%-4% and 15%-20%, respectively. Clinical Considerations Disease-Associated Maternal and/or Embryo/Fetal Risk Pregnant women with congestive heart failure are at increased risk for preterm birth. Stroke volume and heart rate increase during pregnancy, increasing cardiac output, especially during the first trimester. Clinical classification of heart disease may worsen with pregnancy and lead to maternal death. Closely monitor pregnant patients for destabilization of their heart failure . Pregnant women with symptomatic cirrhosis generally have poor outcomes including hepatic failure, variceal hemorrhage, preterm delivery, fetal growth restriction and maternal death. Outcomes are worse with coexisting esophageal varices. Pregnant women with cirrhosis of the liver should be carefully monitored and managed accordingly. […]
If too much is taken
The oral LD 50 of spironolactone is greater than 1000 mg/kg in mice, rats, and rabbits. Acute overdosage of spironolactone may be manifested by drowsiness, mental confusion, maculopapular or erythematous rash, nausea, vomiting, dizziness, or diarrhea. Rarely, instances of hyponatremia, hyperkalemia, or hepatic coma may occur in patients with severe liver disease, but these are unlikely due to acute overdosage. Hyperkalemia may occur, especially in patients with impaired renal function. Treatment: Induce vomiting or evacuate the stomach by lavage. There is no specific antidote. Treatment is supportive to maintain hydration, electrolyte balance, and vital functions. Patients who have renal impairment may develop hyperkalemia. In such cases, discontinue spironolactone.
Before you take anything new
Tell your pharmacist or doctor about every medicine you take — including ones bought without a prescription, herbal products and supplements. Interactions are one of the most common avoidable causes of harm from medicines, and a pharmacist can check your full list in a couple of minutes.
This page is built from the openFDA record of the U.S. Food and Drug Administration's approved labelling for this product, effective 19 November 2025. Label text has been shortened and reformatted for readability; safety wording has not been altered in meaning. FDA labelling describes products approved in the United States — brand names, strengths, formulations and approved uses may differ in your country. Always read the leaflet that comes with your own pack. PocketsInfo is not affiliated with, and is not endorsed by, the FDA. Retrieved 2026-07-30.