Verified
My ankle swelling reduced during the first few weeks. I still needed blood tests, and the increased urination was inconvenient when I took it late in the day.
18 Oct 2026
Aldactone
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Active ingredient
Spironolactone
Aldactone is an oral spironolactone medicine for adults with fluid retention, high blood pressure, heart failure, or selected hormone-related conditions. It helps the kidneys remove excess sodium and water while conserving potassium by blocking aldosterone.
Description
Aldactone contains spironolactone, a potassium-sparing diuretic and aldosterone antagonist. It is prescribed for adults with fluid retention, hypertension, heart failure, primary hyperaldosteronism, and selected hormone-related conditions. By blocking aldosterone, spironolactone helps the kidneys remove sodium and water while reducing potassium loss.
Composition
Aldactone is an oral tablet containing spironolactone. The dose is stated on the pack — follow the leaflet. Spironolactone belongs to two related groups: potassium-sparing diuretics and aldosterone antagonists.
Aldosterone is a hormone produced by the adrenal glands. It signals the kidneys to retain sodium and water while excreting potassium. Spironolactone blocks aldosterone receptors, so the kidneys excrete more sodium and water and retain more potassium [1].
Potassium retention can benefit people who lose potassium with other diuretics. It can also create a serious risk when kidney function is reduced or when other potassium-raising medicines are used.
Spironolactone and tablet strength
The prescribed strength depends on the condition being treated, kidney function, age, potassium level, blood pressure, and concurrent medicines. The dose is stated on the pack — follow the leaflet. A strength suitable for one indication may be unsuitable for another.
Taking spironolactone earlier in the day may reduce night-time urination. The timing should fit the prescribed schedule and the patient’s daily routine.
Aldosterone blockade and potassium preservation
The mechanism follows a clear sequence:
- Spironolactone blocks aldosterone activity.
- The kidneys excrete more sodium.
- Water follows sodium into the urine.
- Fluid load and swelling may decrease.
- Potassium excretion falls.
The effect is not limited to urine volume. Blood pressure, body weight, swelling, kidney function, and serum potassium all influence whether treatment is working safely.
Dosage and usage
- Take Aldactone exactly as prescribed.
- Swallow the tablet with water.
- Take it at a consistent time each day.
- Earlier dosing may reduce sleep disruption from urination.
- Do not double the next dose after a missed dose.
- Keep scheduled blood tests for potassium and creatinine.
- Do not add potassium supplements or potassium-containing salt substitutes without specific approval.
The dose selected by a clinician depends on the indication, age, kidney function, serum potassium, blood pressure, and other medicines. The dose is stated on the pack — follow the leaflet.
If a dose is missed, take it when remembered unless the next dose is due soon. In that situation, skip the missed dose and resume the regular schedule. Taking two doses together can increase dizziness, dehydration, and potassium-related risk.
A late evening dose can lead to repeated overnight urination. A morning or early-afternoon schedule is often more practical when it matches the prescription.
Blood tests commonly include serum potassium and creatinine. Creatinine helps estimate kidney function. The timing of testing depends on the patient’s condition, dose changes, kidney health, and interacting medicines. Results should be interpreted alongside blood pressure, fluid status, and symptoms. Unexpected changes should prompt contact with the prescribing clinician.
How it works
Spironolactone is an aldosterone antagonist that blocks aldosterone receptors in the kidneys. This reduces sodium reabsorption and potassium secretion, causing water to follow sodium into the urine while potassium is retained. Its anti-androgenic effects reduce the action of androgens on certain tissues.
Indications
Aldactone may be prescribed for edema, hypertension, heart failure, congestive heart failure, and primary hyperaldosteronism. The correct indication matters because the dose, treatment duration, and monitoring plan vary between conditions.
| Condition | Treatment purpose | Clinical monitoring |
|---|---|---|
| Edema or heart failure | Reduce excess fluid and swelling | Weight, breathlessness, kidney function, potassium |
| Hypertension | Support blood-pressure control | Blood pressure, kidney function, potassium |
| Primary hyperaldosteronism | Block excess aldosterone effects | Hormone assessment, potassium, kidney function |
Fluid retention and edema management
Edema means abnormal fluid accumulation in tissues. It may occur with heart failure, liver disease, kidney disease, or excess aldosterone. Aldactone can reduce fluid retention, but it does not correct every cause of edema.
Worsening breathlessness, sudden weight gain, rapidly increasing ankle swelling, chest discomfort, or fainting needs prompt medical assessment. A reduction in urination is not automatically a sign of treatment failure, and increased urination alone does not prove that the underlying condition is controlled.
Hypertension treatment
Spironolactone can help lower blood pressure when aldosterone contributes to sodium retention. It may be used alone in selected situations or alongside other antihypertensive treatment. Blood-pressure response and potassium levels require follow-up.
Some patients feel no immediate change even when blood pressure is improving. Home readings can help a clinician assess the response, but treatment changes should be based on a pattern of readings rather than one isolated measurement.
Primary hyperaldosteronism and Conn’s syndrome
Primary hyperaldosteronism, also called Conn’s syndrome, occurs when the adrenal glands produce too much aldosterone. The result may include hypertension and low potassium, though laboratory findings vary.
Diagnosis may involve hormone testing, imaging, and specialist assessment. Treatment depends on whether the cause is related to one adrenal gland, both glands, or another medical factor. Spironolactone blocks aldosterone effects but does not replace the diagnostic investigation.
Hormonal and Dermatological Uses of Spironolactone
Spironolactone also has anti-androgenic effects. Clinicians may prescribe it for selected patients with acne, hirsutism, or symptoms associated with polycystic ovary syndrome (PCOS). These uses may be outside the approved indication in some jurisdictions, so the treatment plan must be individualised.
Anti-androgenic effects
Spironolactone can reduce the effect of androgens on certain tissues. Improvement in acne or unwanted facial hair is gradual and may take several weeks or months. Urine output is not a useful measure of whether a dermatological regimen is helping.
PCOS, acne, and hirsutism treatment context
PCOS can involve irregular periods, acne, excess facial hair, insulin resistance, and other hormonal features. Spironolactone addresses some androgen-related symptoms but does not treat every feature of PCOS.
Comparison
Spironolactone and eplerenone are aldosterone antagonists. Both can reduce aldosterone-mediated sodium retention and require attention to potassium and kidney function.
| Medicine | Pharmacological profile | Common selection factors |
|---|---|---|
| Spironolactone | Aldosterone blockade with anti-androgenic activity | Fluid disorders, heart failure, hyperaldosteronism, selected hormonal conditions |
| Eplerenone | More selective aldosterone receptor blockade | Heart failure or hypertension when fewer hormonal effects are preferred |
Eplerenone may cause fewer anti-androgenic effects, such as breast tenderness or menstrual changes, because it is more selective. Spironolactone may be selected when its broader hormonal action is clinically useful.
Neither medicine is suitable for every patient. Kidney function, potassium, treatment indication, previous adverse effects, local prescribing guidance, and other medicines influence the choice. Switching between them requires a planned medical review.
Contraindications
It should not be used without medical assessment in people with:
- High blood potassium or a history of recurrent hyperkalaemia.
- Significant kidney impairment or rapidly changing kidney function.
- Reduced urine production.
- Addison’s disease or adrenal insufficiency.
- A previous serious allergic reaction to spironolactone.
- Concurrent medicines that create an unacceptable potassium or kidney risk.
ACE inhibitors and ARBs can increase potassium when combined with spironolactone. Ciclosporin can also raise potassium and affect kidney function. Potassium tablets and potassium-containing salt substitutes are easy to overlook during medication reviews.
When this is not for you
Aldactone may not be right for you if you have unstable kidney function, high potassium, reduced urine production, Addison’s disease, or a serious allergy to spironolactone. Tell your clinician if you take ACE inhibitors, ARBs, ciclosporin, potassium tablets, or potassium-based salt substitutes, because these combinations can be unsafe. Pregnancy and breastfeeding also need individual medical advice, particularly when spironolactone is used for acne, hirsutism, or PCOS.
Side effects
Spironolactone is useful for fluid and aldosterone-related conditions, yet potassium retention creates a distinct safety concern. Common unwanted effects include increased urination, dizziness, stomach upset, nausea, breast tenderness, menstrual changes, fatigue, and headache.
Side effects can be more noticeable after starting treatment or increasing the dose. Persistent vomiting, diarrhoea, poor fluid intake, or heavy sweating can increase the risk of dehydration and kidney stress.
Common adverse effects
Increased urination is expected from a diuretic, but severe dizziness or faintness may indicate excessive fluid loss or low blood pressure. Breast tenderness and menstrual changes relate to spironolactone’s hormonal activity.
A mild stomach upset may improve when the tablet is taken with food, if this fits the prescribed instructions. Do not change the dose to manage side effects without a clinician-led review.
Hyperkalaemia and kidney safety
Hyperkalaemia means an abnormally high potassium level in the blood. It may cause muscle weakness, unusual heaviness in the limbs, palpitations, tingling, confusion, or fainting. Severe symptoms require urgent medical attention.
Kidney function deterioration can reduce potassium elimination. The risk rises with dehydration, kidney disease, potassium supplements, potassium-containing salt substitutes, ACE inhibitors, angiotensin II receptor antagonists, and ciclosporin.
A potassium-sparing diuretic does not prevent every electrolyte problem. Sodium, fluid balance, kidney function, and potassium can change together.
Pregnancy, breastfeeding, and hormonal precautions
Spironolactone has anti-androgenic activity and requires careful consideration during pregnancy. Treatment for acne, hirsutism, or PCOS should include a clear pregnancy-prevention plan when clinically appropriate.
Breastfeeding decisions depend on the indication, dose, infant factors, and local product information. Hormonal side effects can be more troublesome when spironolactone is combined with other medicines that affect reproductive hormones.
Common mistakes
- Adding potassium independently: Potassium supplements and salt substitutes can create hyperkalaemia.
- Skipping blood tests because symptoms are absent: Potassium and kidney changes may occur without early warning symptoms.
- Taking a missed dose twice: Doubling can increase dizziness, dehydration, and potassium-related complications.
- Taking the tablet late at night: Night-time urination may disturb sleep.
- Stopping treatment because swelling improves: The underlying condition may still require treatment.
- Using spironolactone for acne without pregnancy planning: Anti-androgenic treatment needs reproductive-health review.
- Assuming all painkillers are harmless: Some anti-inflammatory medicines can affect kidney function and fluid balance.
- Measuring success only by urination: Blood pressure, fluid status, weight, laboratory results, and symptoms matter together.
Bring a current medicine and supplement list to every treatment review. Include herbal products, electrolyte powders, sports drinks, and salt substitutes.
What doctors say
In clinical practice, doctors assess more than urine volume. A patient may urinate more without achieving adequate blood-pressure control, while another may experience a useful reduction in fluid congestion without dramatic changes in daily urine output.
A clinician usually reviews:
- Blood pressure and symptoms of dizziness.
- Body weight and ankle or abdominal swelling.
- Breathlessness and exercise tolerance.
- Serum potassium and creatinine.
- Changes in menstrual pattern or breast symptoms.
- New medicines, supplements, and salt substitutes.
A useful prescribing principle is to start with the indication and risk profile, then select the dose and monitoring schedule. Aldactone should not be judged by one day of symptoms.
Frequently asked questions
What is Aldactone used for?
Aldactone contains spironolactone and is used for conditions involving fluid retention, hypertension, heart failure, and excess aldosterone. It may also be prescribed for selected hormone-related conditions, including acne, hirsutism, or PCOS. FDA prescribing information available in 2023 describes spironolactone’s diuretic and aldosterone-blocking uses.
Does Aldactone raise potassium?
Aldactone can raise potassium because spironolactone reduces potassium excretion in the kidneys. The risk is greater with kidney impairment, dehydration, ACE inhibitors, ARBs, ciclosporin, potassium supplements, and potassium-based salt substitutes. WHO medication-safety guidance published in 2021 supports medication review and laboratory monitoring when potassium-affecting medicines are combined.
Can Aldactone be used for acne or PCOS?
Spironolactone’s anti-androgenic activity may help selected patients with acne, hirsutism, or PCOS-related symptoms. Improvement often takes weeks or months, and menstrual changes or breast tenderness may occur. The European Medicines Agency information current before 2026 supports careful consideration of pregnancy and hormonal safety when anti-androgenic treatment is used.
What should happen after a missed dose?
Take the missed tablet when remembered unless the next scheduled dose is close. Skip it when the next dose is due soon, then continue the regular schedule; do not take two doses together. NICE guidance on medicines for heart failure, published in 2018, emphasises planned dosing and monitoring when mineralocorticoid receptor antagonists are used.
Which tests are used during Aldactone treatment?
Serum potassium and creatinine are commonly monitored because spironolactone affects potassium handling and kidney-related fluid regulation. Blood pressure, body weight, swelling, and symptoms also help assess the response. A 1999 clinical trial published in the New England Journal of Medicine demonstrated the importance of monitoring mineralocorticoid receptor antagonist treatment in heart failure.
Can Aldactone be taken with ACE inhibitors or ARBs?
The combination can be prescribed in selected patients, but ACE inhibitors and ARBs may increase the risk of high potassium or worsening kidney function when used with spironolactone. The regimen requires clinician-led review and blood-test monitoring. FDA prescribing information from 2023 advises reviewing concomitant medicines, supplements, and potassium-containing products.
How does eplerenone differ from spironolactone?
Both medicines block aldosterone receptors, yet eplerenone is more selective and may cause fewer anti-androgenic effects. Spironolactone may be preferred when its broader hormonal activity is useful or when the indication supports it. Kidney function, potassium, heart-failure status, prior side effects, and local prescribing guidance determine the suitable option. NICE guidance published in 2018 discusses mineralocorticoid receptor antagonist treatment and monitoring in heart failure.
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Aldactone: Reviews and Experiences
3.5
Based on 4 reviews
Verified
The medicine was added for heart failure. My weight became steadier, but I felt light-headed after the dose was increased. The treatment plan was adjusted after a blood-pressure review.
9 Oct 2026
Verified
I used spironolactone for hormonal acne. My skin improved slowly rather than immediately. Breast tenderness and irregular periods were the main drawbacks.
25 Oct 2026
Verified
The tablets were easy to take in the morning. I missed one dose and took it at bedtime, which caused a poor night’s sleep, so I returned to the usual schedule.
27 Sep 2026
Sources
- U.S. Food and Drug Administration (2023). Aldactone (spironolactone) Prescribing Information
