Reviewed on 8/18/2021

What Is Spironolactone and How Does It Work?

Spironolactone is used to treat high blood pressure and heart failure. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. It is also used to treat swelling (edema) caused by certain conditions (such as heart failure, liver disease) by removing excess fluid and improving symptoms such as breathing problems.

  • Spironolactone is also used to treat low potassium levels and conditions in which the body is making too much of a natural chemical (aldosterone).
  • Spironolactone is known as a "water pill" (potassium-sparing diuretic).
  • Spironolactone has also been used to treat excessive hair growth (hirsutism) in women with polycystic ovary disease.
  • Spironolactone is available under the following different brand names: Aldactone.

What Are Dosages of Spironolactone?

Dosages of Spironolactone:

Adult and Pediatric Dosage Forms and Strengths


  • 25 mg
  • 50 mg
  • 100 mg
Dosage Considerations – Should be Given as Follows:

Primary Hyperaldosteronism

As a diagnostic agent

  • Long test: 400 mg orally once/day for 3-4 weeks
  • Short test: 400 mg orally once/day for 4 days

Short-term perioperative treatment for adrenalectomy

  • Initial: 100-400 mg orally once/day in preparation for surgery
  • Maintenance: Lowest effective dose individualized for the patient

Geriatric, Initial: 400 mg/day orally, THEN 100-300 mg/day

Edematous Conditions

  • Cirrhosis of the liver with edema and/or ascites; nephrotic syndrome
  • Initial: 100 mg once/day or divided every 12 hours for 5 days; if no clinical response, add the second diuretic with a more specific mechanism of action
  • Range: 25-200 mg orally once/day or divided every 12 hours

Edema, Pediatric (Off-label)

  • CHF, cirrhosis, ascites, and nephrotic syndrome
  • 1-3.3 mg/kg/day orally or divided every 12 hours; not to exceed 3.3 mg/kg/day or up to 100 mg/day

Essential Hypertension

  • Adult, Initial: 25-100 mg orally once/day or divided every 12 hours for more than 2 weeks; adjust to patient response
  • Pediatric: Among therapeutic options recommended by the National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents
  • 1-3.3 mg/kg/day orally or divided every 12 hours; not to exceed 3.3 mg/kg/day or up to 100 mg/day

Congestive Heart Failure

Adult and Geriatric

  • Indicated for NYHA class II/IV heart failure (provided CrCl greater than 30 mL/min and serum K less than 5 mEq/dL)
  • Initial: 25 mg orally once/day
  • Range: 12.5-25 mg/day orally; may increase to 50 mg/day if needed; if 25 mg/day not tolerated, reduce to 25 mg every other day
  • ACC/AHA guidelines recommend aldosterone antagonist to be added to an ACEI or ARB, plus a beta-blocker; patient conditions may also require additional medications (e.g., loop diuretics, hydralazine, nitrates, digoxin)


  • Range: 25-100 mg orally once/day

Diuresis, Geriatric

  • 12.5 mg orally once/day in 1-2 divided doses; increase by 25-50 mg every 5 days as needed; adjust for renal impairment

Hirsutism (Off-label)

Women with hirsutism

  • 50-200 mg orally once/day or divided every 12 hours

Acne (Off-label)

Females with hormonal acne

  • 50-200 mg orally once/day or divided every 12 hours

Hyperaldosteronism (Orphan), Pediatric

Orphan designation for primary hyperaldosteronism


  • CMP Pharma, Inc; orally Box 147, 8026 US Highway 264A; Farmville, NC 27828

Dosing Modifications

Renal impairment

  • CrCl greater than or equal to 50 mL/min/1.73 m²: 12.5-25 mg once/day; use a maintenance dose of 25 mg once/day or every 12 hours after 4 weeks of treatment with potassium less than or equal to 5 mEq/L
  • CrCl 30-49 mL/min/1.73 m²: 12.5 mg once/day or every other day; use a maintenance dose of 12.5-25 mg once/day after 4 weeks of treatment with potassium less than or equal to 5 mEq/L
  • CrCl less than 30 mL/min/1.73 m²: Avoid use

Dosing considerations


  • Caution with heart failure and avoid with CrCl less than 30 mL/min (Beers criteria)
  • In heart failure, the risk of hyperkalemia is higher in older adults, especially if taking greater than 25 mg/day or with concomitant NSAID, ACE inhibitor, ARB, or potassium supplement

Overdose Management


Heart Disease: Symptoms, Signs, and Causes See Slideshow

What Are Side Effects Associated with Using Spironolactone?

Common side effects of spironolactone include:

This is not a complete list of side effects and other serious side effects may occur. Call your doctor for information and medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Spironolactone?

If your doctor has directed you to use this medication for your condition, your doctor or pharmacist may already be aware of any possible drug interactions or side effects and may be monitoring you for them. Do not start, stop, or change the dosage of this medicine or any medicine before getting further information from your doctor, healthcare provider, or pharmacist first.

Severe interactions of spironolactone include:

  • None

Serious interactions of spironolactone include:

Spironolactone has moderate interactions with at least 189 different drugs.

Spironolactone has mild interactions with at least 41 different drugs.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

What Are Warnings and Precautions for Spironolactone?


Spironolactone is tumorigenic in chronic toxicity studies in rats; use only for specified indications.

This medication contains spironolactone. Do not take Aldactone if you are allergic to spironolactone or any ingredients contained in this drug.

Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.


  • Hypersensitivity
  • Anuria
  • Severe renal impairment, acute renal insufficiency
  • Addison's disease or other conditions associated with hyperkalemia
  • Co-administration with eplerenone

Effects of Drug Abuse

  • No information available

Short-Term Effects

  • Somnolence may occur; caution when operating heavy machinery.
  • See "What Are Side Effects Associated with Using Spironolactone?"

Long-Term Effects

  • See "What Are Side Effects Associated with Using Spironolactone?"


  • Use caution in diabetes mellitus, diabetic nephropathy, fluid, and electrolyte imbalance, hepatic disease, metabolic acidosis
  • Concomitant use with potassium-sparing diuretics or ACE inhibitors
  • If used for edema alone, maintain the initial dose for at least 5 days before adjustments
  • Avoid potassium-rich diet or supplements
  • Monitor serum potassium; severe hyperkalemia may occur with concomitant use with other potassium-sparing diuretics, or ACE inhibitors, angiotensin II antagonists, NSAIDs, heparin, LMWH, potassium supplements, salt substitutes, or other drugs known to cause hyperkalemia
  • Risk of potentially fatal hyperkalemia in severe heart failure patients
  • Discontinue if hyperkalemia develops
  • Hyperkalemic metabolic acidosis has been reported in patients given spironolactone concurrently with cholestyramine
  • Risk of gynecomastia and male sexual dysfunction
  • Not recommended for pregnancy-induced hypertension
  • In cirrhosis, avoid electrolyte and acid/base imbalances that might lead to hepatic encephalopathy
  • Somnolence may occur; caution when operating heavy machinery
  • Excess amounts of electrolyte loss can result in profound diuresis; adjust to avoid dehydration; correct electrolyte disturbances resulting from therapy
  • Discontinue use before adrenal vein catheterization
  • The risk of hyperkalemia increases with declining renal function
  • The risk of orthostasis may occur with concurrent ethanol use

Pregnancy and Lactation

  • Use spironolactone with caution during pregnancy if the benefits outweigh the risks. Animal studies show risk and human studies are not available or neither animal nor human studies are done.
  • Metabolites of spironolactone are excreted into breast milk; discontinue breastfeeding or do not use spironolactone.


In the U.S., 1 in every 4 deaths is caused by heart disease. See Answer

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