Verified
My ankle swelling had reduced by the second week and I was less breathless on stairs. The blood tests were arranged after starting, which reassured me because I was already taking heart medicines.
12 Sep 2026
Aldactone
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Active ingredient
Spironolactone
Aldactone is a prescription tablet containing spironolactone for adults who need treatment for fluid retention or certain heart and blood-pressure conditions. It helps the kidneys remove sodium and water while limiting potassium loss by blocking aldosterone.
Description
Aldactone is a spironolactone tablet; the dose is stated on the pack — follow the leaflet. It is used in adults with fluid retention, heart failure, hypertension, or excess aldosterone, where blocking aldosterone helps the body remove sodium and water while retaining potassium.
Composition
Aldactone contains spironolactone per tablet; the dose is stated on the pack — follow the leaflet. Spironolactone is an aldosterone antagonist and potassium-sparing diuretic. It reduces the hormonal signal that makes the kidneys retain sodium and water.
Spironolactone appears on the WHO Model List of Essential Medicines for selected cardiovascular and endocrine uses, reflecting its established role in clinical care [1].
- Active ingredient: spironolactone
- Drug class: aldosterone antagonist
- Diuretic effect: increases sodium and water excretion
- Potassium effect: reduces potassium loss compared with loop or thiazide diuretics
Potassium monitoring is central.
Aldactone does not act like a fast, strong water tablet for every person. Its value often comes from blocking aldosterone, a hormone that drives fluid retention and can worsen heart failure.
Dosage and usage
Aldactone tablets are swallowed with water. The prescribed regimen depends on the reason for treatment, kidney function, potassium concentration, other diuretics, and medicines used for heart or blood-pressure control.
The dose is stated on the pack — follow the leaflet. It is not the standard starting dose for every condition. For heart failure with reduced ejection fraction, guideline-directed treatment often starts with lower spironolactone doses and is adjusted after laboratory monitoring [3].
- Take Aldactone at the same time each day.
- Morning use can be more convenient when increased urination occurs.
- Take it with food if stomach upset occurs.
- Do not double a missed dose.
- If a dose is missed, take it when remembered unless the next scheduled dose is near.
- Skip the missed dose when the next dose is due soon, then continue the usual schedule.
Patients who take Aldactone late in the evening sometimes wake to urinate. A morning schedule can reduce this disruption unless the prescriber has set a different plan.
How it works
Aldosterone tells the kidneys to retain sodium and water while releasing potassium. Spironolactone blocks aldosterone receptors in the distal nephron, the kidney segment that fine-tunes electrolyte balance. More sodium and water leave through urine, while potassium is retained.
This mechanism can reduce swelling in the ankles, abdomen, or lungs when excess fluid is present. In heart failure, aldosterone blockade also limits harmful hormonal effects on the heart and blood vessels. The landmark Randomized Aldactone Evaluation Study found that spironolactone reduced mortality and hospital admissions in people with severe heart failure receiving standard treatment [2].
Indications
- Main adult uses: heart failure, oedema, hypertension, liver-related fluid retention, nephrotic syndrome, and primary hyperaldosteronism
Comparison
Aldactone is selected when aldosterone blockade and potassium retention are clinically useful. Other diuretics remove fluid through different kidney pathways and have different electrolyte effects.
| Option | Main action | Key difference |
|---|---|---|
| Spironolactone | Blocks aldosterone receptors | Retains potassium and has hormonal adverse effects |
| Furosemide | Loop diuretic | Produces stronger, faster fluid removal but may lower potassium |
| Hydrochlorothiazide | Thiazide diuretic | Often used for blood pressure; may lower potassium and sodium |
Loop diuretics are commonly used when fluid overload needs prompt relief. Spironolactone may be added when aldosterone activity is contributing to persistent oedema or heart failure risk. Thiazide diuretics are often chosen for uncomplicated hypertension, while Aldactone can be useful in resistant hypertension or proven excess aldosterone.
Aldactone has a limitation: potassium can rise too high, especially when kidney function is reduced. Furosemide and hydrochlorothiazide more often cause low potassium, dehydration, or low sodium.
Contraindications
Aldactone is not for you if you have anuria, acute kidney failure, significant kidney impairment with unsafe potassium handling, hyperkalaemia, or Addison’s disease. It is also unsuitable for anyone with a known allergy to spironolactone or a tablet ingredient.
Avoid or closely monitor combinations with:
- potassium supplements;
- potassium-containing salt substitutes;
- ACE inhibitors;
- angiotensin receptor blockers;
- sacubitril/valsartan;
- trimethoprim or trimethoprim-sulfamethoxazole;
- non-steroidal anti-inflammatory drugs such as ibuprofen or diclofenac;
- ciclosporin or tacrolimus;
- digoxin;
- lithium;
- other potassium-sparing diuretics.
When this is not for you
This medicine may not be suitable if you cannot pass urine, have serious kidney problems, high potassium, Addison’s disease, or an allergy to spironolactone or one of the tablet ingredients. Pregnancy, breastfeeding, liver disease, diabetes affecting the kidneys, and older age with reduced kidney reserve require medical review before treatment. Do not start potassium supplements or use potassium-containing salt substitutes without checking with your prescriber.
Side effects
Aldactone is usually tolerated when the dose, kidney function, and potassium concentration are monitored. Its adverse effects follow from potassium retention and from spironolactone’s interaction with androgen and progesterone receptors.
Common effects can include:
- increased urination;
- dizziness, especially when standing quickly;
- stomach upset, nausea, diarrhoea, or abdominal cramps;
- headache or fatigue;
- breast tenderness;
- menstrual irregularities;
- reduced libido or erectile difficulties;
- breast enlargement in men, known as gynaecomastia.
Gynaecomastia can be dose-related and may become troublesome during long-term treatment. The FDA prescribing information also lists hyperkalaemia, worsening kidney function, low sodium, allergic reactions, and rare serious skin reactions among clinically relevant risks [4].
Seek urgent medical assessment for fainting, severe weakness, confusion, a slow or irregular heartbeat, facial swelling, blistering rash, or markedly reduced urination. These symptoms can indicate a major electrolyte problem, kidney impairment, or serious hypersensitivity reaction.
Do not replace ordinary salt with potassium-containing salt substitutes while taking Aldactone unless the prescriber has specifically approved it. These products can raise potassium without changing the taste of food very much.
Common mistakes
- Using potassium supplements without declaring them. This can produce hyperkalaemia even when Aldactone itself was prescribed appropriately.
- Taking anti-inflammatory painkillers regularly. Ibuprofen, naproxen, and diclofenac can affect kidney blood flow and potassium balance.
- Doubling the next dose after forgetting one. This does not restore the missed benefit and may increase dizziness or electrolyte changes.
- Stopping treatment because urination increases slightly. Mild diuresis can be expected; severe thirst, faintness, or very low urine output needs assessment.
- Ignoring breast tenderness or enlargement. These effects are not dangerous in every case, yet they can affect adherence and should be discussed early.
- Assuming a normal blood-pressure reading means monitoring is unnecessary. Potassium and kidney function can change without a noticeable blood-pressure rise.
Keep a current medicines list that includes painkillers, cold remedies, supplements, and salt substitutes. These are the items most often missed when potassium-related interactions are reviewed.
What doctors say
In clinical practice, physicians tend to view Aldactone as a targeted medicine rather than a routine fluid tablet. It has a clear role when aldosterone is contributing to resistant hypertension, persistent fluid retention, cirrhosis-related ascites, or heart failure with reduced ejection fraction. The first question is often not whether spironolactone can help, but whether the kidneys can safely handle the potassium-retaining effect.
Doctors commonly arrange potassium and creatinine testing before treatment and after starting or changing the dose. A normal potassium result before treatment does not guarantee it will remain normal after adding an ACE inhibitor, an ARB, or an NSAID. Symptom improvement may be gradual. Swelling can ease before the full cardiovascular benefit becomes clear. NICE guidance for chronic heart failure, updated in 2023, places mineralocorticoid receptor antagonists within evidence-based treatment for eligible patients with reduced ejection fraction [5].
Frequently asked questions
Is Aldactone used for high blood pressure?
Aldactone can be prescribed for hypertension, especially resistant hypertension or high blood pressure linked to excess aldosterone. It is often used with other blood-pressure medicines rather than as the only treatment. The 2023 American Heart Association heart-failure guideline also recognises mineralocorticoid receptor antagonists as medicines that require renal and potassium monitoring. The right dose depends on the treatment goal and laboratory results.
How quickly does Aldactone reduce swelling?
Urine output may increase within the first few days, though visible improvement in swelling can take longer. Ascites, heart-failure oedema, and liver-related fluid retention may need additional diuretic treatment and careful adjustment. The FDA revised its Aldactone prescribing information in 2023 and continues to emphasise monitoring for fluid, electrolyte, and kidney changes. Rapid weight loss, intense thirst, or dizziness can signal excessive fluid loss.
Can Aldactone raise potassium levels?
Yes. Spironolactone reduces potassium excretion through the kidneys, which is useful for people prone to low potassium from other diuretics. The same effect can cause hyperkalaemia when kidney function is impaired or when potassium-raising medicines are combined. WHO guidance published in 2023 lists spironolactone within established essential cardiovascular medicines, while its use still requires appropriate clinical monitoring. Weakness, abnormal heart rhythm, and severe fatigue need urgent assessment.
Can men develop breast enlargement with Aldactone?
Yes. Spironolactone can cause breast tenderness or gynaecomastia because it affects hormonal receptors in addition to blocking aldosterone. The risk can rise with higher doses and longer exposure, though individual sensitivity varies. FDA safety information updated in 2023 includes gynaecomastia among recognised adverse reactions. Report breast changes early, since an alternative aldosterone-blocking strategy may be considered.
Can Aldactone be taken with ibuprofen?
Regular ibuprofen, naproxen, diclofenac, and similar NSAIDs may reduce the diuretic effect and increase kidney and potassium risks. A single dose may not cause a problem for every person, yet repeated use deserves review when Aldactone is part of the regimen. The EMA’s Good Pharmacovigilance Practices guidance, revised in 2017, highlights the value of recognising medicine combinations that can change renal safety. Paracetamol is often considered for pain instead, depending on the person’s medical history and prescribed treatment.
Is Aldactone suitable during pregnancy?
Spironolactone is generally avoided during pregnancy because of its anti-androgen activity and potential effects on fetal sexual development. Treatment for hypertension or fluid retention during pregnancy needs an obstetric and prescribing review. NICE guidance published in 2023 supports condition-specific treatment planning rather than self-adjusting cardiovascular medicines during pregnancy. Do not stop a prescribed medicine abruptly without arranging a replacement plan when pregnancy is possible or confirmed.
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Comparison
Compare all medications for HypertensionAldactone: Reviews and Experiences
3.6
Based on 4 reviews
Verified
I used it for blood pressure that stayed high despite another tablet. I needed to move the dose to the morning because taking it after dinner made me wake during the night.
7 Sep 2026
Verified
The fluid in my legs improved, but I developed breast tenderness after several weeks. My clinician changed the plan rather than telling me to ignore it.
30 Aug 2026
Verified
I felt light-headed when standing during the first few days. Drinking normally and getting up slowly helped, but the dose still needed review after my blood pressure became lower than expected.
15 Aug 2026
Sources
- World Health Organization (2023). WHO Model List of Essential Medicines: 23rd List, 2023.
- New England Journal of Medicine (1999). The Effect of Spironolactone on Morbidity and Mortality in Patients with Severe Heart Failure.
- American Heart Association, American College of Cardiology and Heart Failure Society of America (2022). 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure.
- U.S. Food and Drug Administration (2023). Aldactone (spironolactone) Tablets: Prescribing Information.
- National Institute for Health and Care Excellence (2023). Chronic Heart Failure in Adults: Diagnosis and Management.
