Medications Directory

Approved indications: Orally, spironolactone is approved for adults with NYHA class III–IV heart failure with reduced ejection fraction (added to standard therapy to improve survival, reduce hospitalizations, and lessen edema), as add‑on treatment for hypertension not fully controlled on other agents, for edema related to cirrhosis or nephrotic syndrome when other measures are inadequate, and for primary hyperaldosteronism (short‑term pre‑operative and long‑term maintenance when surgery is not suitable).

Off‑label uses and evidence: Clinicians commonly prescribe spironolactone off label for hormonally driven acne in adult women, hirsutism and other androgen‑excess states (such as some cases of polycystic ovary syndrome), and female‑pattern hair loss. Randomized controlled trials and meta‑analyses show spironolactone significantly improves acne severity and quality of life compared with placebo and provides clinically meaningful reductions in hirsutism scores, while evidence for female‑pattern hair loss is more limited and largely observational.

Efficacy expectations: In severe heart failure, adding low‑dose spironolactone (for example 25 mg daily) to standard therapy has been shown to cut all‑cause mortality and heart‑failure hospitalizations by about one‑third over roughly two years, with symptom improvement often within weeks. For hypertension, blood‑pressure lowering is usually apparent within days to a few weeks, with maximal effect after several weeks of stable dosing. For edema in cirrhosis or nephrotic syndrome, gradual reduction in swelling typically occurs over days to weeks, especially when combined with sodium restriction and other diuretics. For acne, noticeable improvement generally begins after 2–3 months and continues over 4–6 months; hirsutism and hair‑related benefits are slower, often requiring 6–12 months of continuous therapy. Compared with other mineralocorticoid receptor antagonists such as eplerenone, spironolactone is at least as effective for fluid and blood‑pressure control but has more endocrine side effects (e.g., breast tenderness, menstrual changes), while offering an important non‑antibiotic systemic option for women with acne.

Typical adult dosing by indication (oral): For NYHA class III–IV heart failure with reduced ejection fraction, therapy usually starts at 25 mg once daily (sometimes 25 mg every other day if kidney function is borderline), with potential increase to 50 mg daily if potassium remains normal. For hypertension, common doses are 25–100 mg per day given once daily or divided, as add‑on therapy. For edema due to cirrhosis or nephrotic syndrome, initial total daily doses often range from 25–100 mg and may be titrated up to about 200 mg per day if needed and tolerated. For primary hyperaldosteronism, doses are typically higher (around 100–400 mg per day) short‑term before surgery or adjusted to the lowest effective maintenance dose when surgery is not an option.

Formulations and how to take it: Spironolactone is available as tablets and as an oral suspension; some branded suspensions are not milligram‑for‑milligram equivalent to tablets and use lower numerical doses to produce similar blood levels, so product‑specific instructions must be followed. The medicine can be taken with or without food, but should be taken the same way every day with respect to meals. Because it increases urination, many people take it once daily in the morning; if a second dose is prescribed, it is often given in the late afternoon rather than at bedtime to limit nighttime urination. Tablets should be swallowed whole; oral suspension should be measured with an appropriate dosing syringe or cup and shaken well before use.

Special dosing instructions: Dosing is individualized based on kidney function, baseline potassium, and concomitant medications. Lower starting doses and slower titration are used in older adults, those with reduced eGFR, or people taking ACE inhibitors, ARBs, or other drugs that raise potassium. The medicine should not be started if potassium is elevated or kidney function is severely impaired, and it may need to be held during acute illness, dehydration, or when contrast dye or nephrotoxic drugs are used.

Missed dose guidance: If a dose is missed, it should be taken as soon as remembered unless it is almost time for the next scheduled dose; in that case, the missed dose should be skipped and the regular schedule resumed. Two doses should not be taken at once to “make up” for a missed dose.

Overdose: Taking too much spironolactone can cause drowsiness, confusion, severe nausea or vomiting, dizziness, low blood pressure, and dangerous electrolyte disturbances (especially high potassium). In case of suspected overdose, no additional doses should be taken; emergency medical care or poison‑control assistance (1‑800‑222‑1222 in the U.S.) should be sought immediately.

Common side effects: The most frequent problems include increased urination, dizziness or lightheadedness (especially when standing up), gastrointestinal upset (nausea, diarrhea, stomach cramps), fatigue, headache, breast tenderness or enlargement in any sex, and menstrual irregularities or spotting in women. Many effects are mild to moderate, appear in the first days to weeks of treatment, and may improve as the body adjusts or with dose reduction.

Electrolyte and kidney effects: Spironolactone can raise blood potassium (hyperkalemia) and, less often, lower sodium, and can worsen kidney function, especially in people with chronic kidney disease, diabetes, older age, or those taking other potassium‑raising drugs. Hyperkalemia may cause no symptoms or present with muscle weakness, tingling, nausea, or heart rhythm problems, so regular blood tests for potassium and creatinine are essential.

Serious or rare adverse effects: Seek urgent medical attention for signs of severe hyperkalemia (marked weakness, slow or irregular heartbeat, fainting), severe dehydration or low blood pressure (confusion, extreme dizziness, inability to stay awake), breathing trouble, swelling of the face, lips, tongue, or throat, or a severe skin reaction with blistering or peeling. In patients with advanced liver disease, rapid shifts in fluid and electrolytes can precipitate confusion or hepatic encephalopathy. Very rarely, serious blood, liver, or skin reactions have been reported with potassium‑sparing diuretics.

Warnings and precautions (pregnancy, breastfeeding, age, organ disease): Because spironolactone blocks androgen effects and has caused feminization of male fetuses in animal studies, it is generally avoided during pregnancy unless the potential benefit clearly outweighs the risk; people who could become pregnant are usually advised to use effective contraception while taking it. Spironolactone and its active metabolite appear in breast milk in very low amounts and short‑term use is generally considered compatible with breastfeeding, but long‑term infant effects are not fully known, so decisions are individualized. The drug is substantially cleared by the kidneys and used cautiously, at lower doses and with close monitoring, in older adults and those with kidney impairment or advanced liver disease. It is contraindicated in people with hyperkalemia, Addison’s disease, or concurrent eplerenone.

Comparative safety: Versus loop and thiazide diuretics, spironolactone carries far less risk of low potassium but significantly higher risk of high potassium and endocrine effects such as gynecomastia and menstrual disturbances. Compared with eplerenone, spironolactone tends to cause more breast and menstrual side effects but is more widely studied and less expensive; with careful monitoring, overall serious toxicity remains uncommon when labeled precautions are followed.

Monitoring and safety updates: Before and during therapy, clinicians typically monitor blood pressure, weight, kidney function, and serum electrolytes (especially potassium). Potassium and creatinine are usually checked within about one week of starting or changing the dose, then periodically thereafter, with more frequent testing in high‑risk patients or when combined with ACE inhibitors, ARBs, or other potassium‑raising agents. Side effects and product problems can be reported to the U.S. Food and Drug Administration through the MedWatch program (online or by calling 1‑800‑FDA‑1088), and up‑to‑date safety information is available on the FDA website.

Key drug and supplement interactions:

• Potassium‑raising agents: ACE inhibitors, ARBs, direct renin inhibitors, other potassium‑sparing diuretics (e.g., amiloride, triamterene), potassium supplements, and potassium‑containing salt substitutes all increase the risk of hyperkalemia when combined with spironolactone.
• Trimethoprim (alone or in combination such as trimethoprim‑sulfamethoxazole): Has its own potassium‑sparing effect and can markedly increase the risk of severe hyperkalemia when used together.
• NSAIDs (e.g., ibuprofen, naproxen), high‑dose COX‑2 inhibitors: May blunt the diuretic and blood‑pressure effect and further stress the kidneys, increasing the risk of renal impairment and hyperkalemia.
• Lithium: Concomitant use may raise lithium levels and increase lithium toxicity risk; combination is usually avoided or requires close monitoring.
• Digoxin: Spironolactone and its metabolites can increase apparent digoxin levels and interfere with some digoxin assays, so clinicians may adjust digoxin dosing and interpret drug‑level results cautiously.
• Cholestyramine and high‑dose salicylates: May alter spironolactone efficacy or contribute to metabolic disturbances; combined use is monitored carefully.

Food, alcohol, and lifestyle considerations: A low‑sodium diet often enhances the diuretic effect. Because of hyperkalemia risk, potassium‑rich salt substitutes should be avoided and intake of very high‑potassium foods (such as large daily quantities of bananas, orange juice, or dried fruits) is often moderated according to lab results. Alcohol can enhance dizziness or low blood pressure and may worsen heart failure; patients are usually advised to limit or avoid it, especially at the start of therapy or after dose changes.

Conditions and co‑medications requiring caution or avoidance: Spironolactone is contraindicated in patients with existing hyperkalemia, Addison’s disease, or concurrent eplerenone. It must be used very cautiously, if at all, in advanced chronic kidney disease, acute kidney injury, severe liver disease with unstable fluid status, uncontrolled diabetes with kidney involvement, or in combination with multiple other potassium‑raising drugs. In pregnancy, especially with a male fetus, alternative agents are usually preferred unless spironolactone is clearly necessary.

Monitoring needs: Regular laboratory monitoring of serum potassium, sodium, bicarbonate, creatinine, and estimated GFR is central to safe long‑term use, especially after initiation, dose adjustments, intercurrent illness, or adding interacting drugs. Blood pressure, weight, and signs of fluid overload or dehydration are typically checked at each visit. Electrocardiograms may be obtained if significant electrolyte abnormalities are suspected or if the patient develops palpitations or syncope.

Q: What is spironolactone most commonly used for?
A: Orally, spironolactone is mainly used to treat certain types of heart failure, high blood pressure, and fluid buildup from liver or kidney disease, and is also frequently prescribed off label for hormonally driven acne and excess hair growth in women.

Q: How long does it take spironolactone to start working?
A: For swelling and heart‑failure symptoms, some improvement may appear within days to a couple of weeks, while blood‑pressure effects often stabilize over several weeks; for acne or hirsutism, noticeable changes usually take 2–3 months and may continue to improve for 6–12 months.

Q: Do I need regular blood tests while taking spironolactone?
A: Yes, because spironolactone can raise potassium and affect kidney function, clinicians typically check blood potassium and creatinine within about a week of starting or changing the dose and then at regular intervals, especially if you have kidney disease, diabetes, or take other potassium‑raising medicines.

Q: Can I eat foods high in potassium or use salt substitutes?
A: Many people on spironolactone can eat a normal diet, but potassium‑containing salt substitutes and very high intakes of potassium‑rich foods may raise potassium too much, so you should follow your clinician’s dietary advice and never start potassium supplements without medical approval.

Q: Is spironolactone safe in pregnancy or while breastfeeding?
A: Because animal studies show potential effects on male fetal development, spironolactone is generally avoided during pregnancy unless the benefits clearly outweigh the risks; small amounts of its active metabolite enter breast milk and short‑term use appears compatible with breastfeeding, but long‑term use while nursing should be discussed carefully with your clinician.

Q: Why can spironolactone affect periods, breasts, or body hair?
A: Spironolactone blocks some actions of androgens (male‑type hormones), which can help treat acne and excess hair but may also cause side effects such as irregular periods, breast tenderness or enlargement, and changes in body or facial hair patterns in some people.