Aldosterone Antagonist / Potassium-Sparing Diuretic Pregnancy: Spironolactone or its metabolites may cross the placental barrier; feminisation has been observed in male rat fetuses. Use in pregnant women requires that the anticipated benefit be weighed against the possible hazards to mother and fetus. Breast-feeding: metabolites have been detected in breast milk — if use is considered essential, an alternative method of infant feeding should be instituted.

Spironolactone (Ascites / Cirrhosis)

Brand names: Aldactone

Spironolactone is an aldosterone-receptor antagonist (potassium-sparing diuretic) used here as the first-line diuretic for fluid retention and ascites in cirrhosis, where secondary hyperaldosteronism drives sodium and water retention.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Hepatic cirrhosis with ascites and oedema: 100 mg daily if urinary Na+/K+ ratio is greater than 1.0; 200 mg to 400 mg daily if the ratio is less than 1.0

Route: Oral

Frequency: Once daily with a meal (SPC: 'Administration of spironolactone tablets once daily with a meal is recommended'); doses for other indications may be given in single or divided doses

Max: Not stated as a maximum in §4.2; the highest dose quoted for ascites is 400 mg daily

Maintenance dosage should be individually determined. Other indications stated in the same SPC: malignant ascites — initial dose usually 100 mg/day to 200 mg/day, in severe cases the dosage may be gradually increased up to 400 mg/day, with maintenance individually determined once oedema is controlled; congestive cardiac failure with oedema — initial 100 mg daily (range 25 mg to 200 mg daily); severe heart failure (NYHA III–IV) — initiate 25 mg once daily if serum potassium is 5.0 mEq/L or less and serum creatinine is 2.5 mg/dL or less, increase to 50 mg once daily if tolerated, reduce to 25 mg every other day if not tolerated; nephrotic syndrome — usual dose 100 mg/day to 200 mg/day; primary aldosteronism — 400 mg daily for 3 to 4 weeks (long test) or 400 mg daily for 4 days (short test), then 100 mg to 400 mg daily in preparation for surgery. Elderly: start with the lowest dose and titrate upwards as required; care with severe hepatic and renal impairment. Monitoring in severe heart failure: potassium and creatinine 1 week after initiation or dose increase, monthly for the first 3 months, then quarterly for a year, then every 6 months; discontinue or interrupt for serum potassium above 5 mEq/L or serum creatinine above 4 mg/dL. Reversible hyperchloraemic metabolic acidosis, usually with hyperkalaemia, has been reported in some patients with decompensated hepatic cirrhosis even with normal renal function (§4.4).

Paediatric dose

Route: Oral

Frequency: Divided doses (initial daily dosage)

Max: Not stated in source

SPC §4.2 states: 'Initial daily dosage should provide 1-3 mg of spironolactone per kilogram body weight given in divided doses' — a 1 to 3 mg/kg/day range, so no single per-kg number is given. Dosage should be adjusted on the basis of response and tolerance. Children should only be treated under the guidance of a paediatric specialist; there is limited paediatric data available. Contraindicated in paediatric patients with moderate to severe renal impairment. Verify any paediatric dose against a children's formulary before use. (US labelling states safety and effectiveness in paediatric patients have not been established.)

Dose adjustments

Renal

No numeric dose reduction is given in §4.2. Contraindicated in acute renal insufficiency, significant renal compromise and anuria (§4.3). Hyperkalaemia may occur in patients with impaired renal function; fluid and electrolyte status should be regularly monitored, particularly in the elderly and in those with significant renal and hepatic impairment. Reversible increases in blood urea have been reported, particularly with impaired renal function.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Acute renal insufficiency, significant renal compromise, anuria
Addison's disease
Hyperkalaemia
Hypersensitivity to spironolactone or to any of the excipients
Concomitant use of eplerenone or other potassium-sparing diuretics
Paediatric patients with moderate to severe renal impairment
Potassium supplements should not be given routinely with spironolactone as hyperkalaemia may be induced

Side effects

Gynaecomastia (dose- and duration-related; normally reversible on discontinuation, rarely some breast enlargement persists)
Hyperkalaemia; electrolyte imbalance
Breast pain (male and female); menstrual disorder; libido disorder
Nausea and other gastrointestinal disorder
Dizziness; confusional state
Pruritus, rash, urticaria
Acute kidney injury

Interactions

Drugs known to cause hyperkalaemia — may result in severe hyperkalaemia (other potassium-sparing diuretics, ACE inhibitors, NSAIDs, angiotensin II antagonists, aldosterone blockers, heparin and low molecular weight heparin, potassium supplements, potassium-rich diet or salt substitutes containing potassium)
Trimethoprim/sulfamethoxazole (co-trimoxazole) — may result in clinically relevant hyperkalaemia
Digoxin — spironolactone has been reported to increase serum digoxin concentration and to interfere with certain serum digoxin assays

Clinical monograph

How it works

It competitively blocks the mineralocorticoid receptor in the distal nephron, promoting sodium and water excretion while retaining potassium, directly countering the high aldosterone state of decompensated liver disease.

Prescribing in practice

Hyperkalaemia is the principal hazard — risk is compounded in cirrhosis by renal impairment and concurrent ACE inhibitors, ARBs or potassium supplements, and can precipitate dangerous arrhythmia.
It is the preferred initial diuretic in cirrhotic ascites and is often paired with a loop diuretic (e.g. furosemide) when used at higher intensity to maintain a balanced electrolyte effect.
Aim for gradual fluid loss and watch for over-diuresis, which can precipitate hyponatraemia, hepatic encephalopathy or hepatorenal deterioration.

Monitoring

Monitor serum potassium, sodium, renal function and body weight regularly, particularly after initiation or dose changes.

Counselling the patient

Report muscle weakness, palpitations or confusion, which may signal electrolyte disturbance.
Avoid potassium-containing salt substitutes and over-the-counter potassium supplements.
Men may notice breast tenderness or enlargement (gynaecomastia) with prolonged use.

Evidence & guidelines

Spironolactone-based regimens are endorsed by NICE and EASL guidance as first-line diuretic therapy for cirrhotic ascites.

Reference: EASL Clinical Practice Guidelines on Cirrhosis 2018; Baveno VII Consensus 2022; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways