Spironolactone

About Spironolactone

Spironolactone blocks aldosterone, a hormone that makes the kidneys hold on to salt and water and lose potassium. The tablet label covers NYHA class III to IV heart failure with reduced ejection fraction, to improve survival, manage edema and reduce hospital admissions for heart failure; add-on treatment of high blood pressure; edema from cirrhosis that does not respond to fluid and salt restriction, and from nephrotic syndrome when other treatment falls short; and primary hyperaldosteronism, before surgery or long term when surgery is not an option. Safety and effectiveness in children have not been established. In heart failure it starts at 25 mg once a day if potassium and kidney function allow, rising to 50 mg or dropping to 25 mg every other day. Blood pressure doses are 25 to 100 mg a day; edema usually starts at 100 mg a day, in hospital for cirrhosis; and hyperaldosteronism takes 100 to 400 mg a day before surgery.

The current Aldactone label has no boxed warning; older labels opened with a warning that it caused tumors in rats, and those findings now sit in its nonclinical section. It must not be taken with high potassium, Addison’s disease or eplerenone. It can raise potassium, especially with kidney impairment, potassium supplements, salt substitutes, ACE inhibitors or ARBs, so potassium is checked within a week of starting or changing the dose and regularly after, and the dose is cut or stopped if it rises. Too much fluid loss can drop blood pressure and worsen kidney function, and it can lower sodium and magnesium and raise blood sugar and uric acid. Breast enlargement in men (gynecomastia), its most common side effect, rises with the dose, can appear from one or two months to over a year after starting and usually reverses; breast or nipple pain, irregular periods and erection problems are also reported.

CaroSpir is labeled for heart failure, add-on blood pressure treatment and edema from cirrhosis in adults, at its own doses (for heart failure, 20 mg rising to 37.5 mg); its label says it is not therapeutically equivalent to Aldactone, that anyone needing more than 100 mg should use another form, and that it is not recommended for high blood pressure in children. In pregnancy spironolactone may affect the development of a male fetus, so the label advises avoiding it or explaining that risk; the medicine itself has not been found in breast milk, though low levels of an active metabolite have been reported. In November 2025 the Aldactone label added that it lowers blood levels of mitotane, a cancer medicine, so the two are not combined. Acne, excess hair growth and polycystic ovary syndrome are not FDA-approved uses.

Taking Spironolactone

How to take it

Once a day or in divided doses as prescribed, always the same way with respect to food, since food increases how much is absorbed. Shake the suspension well before each dose. The full effect can take about two weeks or longer.

If you miss a dose

Take it as soon as you remember, unless it is almost time for the next dose; then skip the missed dose and carry on as usual. Do not take a double dose.

Storage

Aldactone tablets below 77°F (25°C) and the suspension at room temperature, in tightly closed containers away from excess heat and moisture, not in a bathroom and out of reach of children.

Interactions to know about

Potassium supplements, potassium-containing salt substitutes, ACE inhibitors, ARBs, NSAIDs, heparin and trimethoprim can push potassium dangerously high, and it raises lithium levels. NSAIDs and aspirin can blunt its effect, cholestyramine has been linked to high potassium with acid buildup in the blood, it can interfere with some digoxin blood tests, and it is not combined with eplerenone, abiraterone or mitotane.

This summarizes the official prescribing information. Your prescriber’s and pharmacist’s instructions, and the leaflet that comes with your medicine, take priority.

Why the cash price for Spironolactone differs from pharmacy to pharmacy

Generic spironolactone tablets have many makers and cost pharmacies little, so a quote is mostly the dispensing fee and markup, which differ between pharmacies. A prescription that names Aldactone and blocks substitution is priced as a brand.

The suspension has fewer makers than the tablets, and a pharmacist cannot switch between suspension and tablets.

Ways to pay less for Spironolactone without insurance

• Ask for generic spironolactone, make sure the prescription does not block substitution, ask whether it is on the pharmacy’s flat-price generic list, and compare more than one pharmacy.
• Ask the prescriber to write your dose with the fewest tablets, for example one 100 mg tablet rather than four 25 mg tablets.
• Once your dose and potassium are stable, ask for a ninety-day supply.
• If the suspension is prescribed, ask for a generic rated equivalent to CaroSpir; if you can swallow tablets, ask the prescriber whether tablets, at a tablet dose, would suit you.
• Upload the prescription to Script Unlock so licensed pharmacies can quote their cash price. You pay the pharmacy directly.

Questions to ask your pharmacist about Spironolactone

1. 1.When will my potassium and kidney function be checked?
2. 2.Should I stop my potassium supplement or salt substitute?
3. 3.Is it safe with my blood pressure medicines, trimethoprim or ibuprofen?
4. 4.What should I do about breast tenderness or swelling?

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