Indications
Spironolactone is a water tablet (diuretic) that keeps potassium in the body. It is used for:
- Heart failure, usually alongside other heart medicines
- Fluid build-up (oedema) from liver disease (ascites), kidney disease (nephrotic syndrome) or heart failure
- High blood pressure that is hard to control
- Primary hyperaldosteronism (the adrenal glands make too much of the hormone aldosterone)
- On a specialist’s advice: excess hair growth and acne in women
How It Works
It blocks aldosterone, a hormone that makes the kidneys hold on to salt and water. The kidneys then pass more salt and water but keep potassium. This reduces swelling and blood pressure and protects the heart.
Dosage and Administration
Adults, usual doses (the doctor sets the exact dose):
- Heart failure: 25 mg once a day, sometimes increased to 50 mg
- High blood pressure: 25 to 100 mg a day
- Oedema and ascites: often 100 mg a day, adjusted by the doctor
- Hyperaldosteronism, skin conditions and children: as prescribed
Take with food, preferably in the morning. Blood tests for potassium and kidney function are needed, especially in the first weeks and after a dose change.
Interactions
- Potassium supplements, salt substitutes containing potassium, and other potassium-keeping diuretics (such as Amiloride, Triamterene or Eplerenone): risk of dangerously high potassium
- ACE inhibitors (such as Enalapril, Ramipril) and ARBs (such as Losartan): often used together but need close potassium checks
- Trimethoprim, Ciclosporin, Tacrolimus and Heparin: may raise potassium
- Painkillers such as Ibuprofen, Diclofenac and other NSAIDs: can raise potassium, harm the kidneys and reduce the effect
- Digoxin and Lithium: levels may rise
Contraindications
- High blood potassium
- Severe kidney failure or no urine production
- Addison’s disease (adrenal gland failure)
- Taking Eplerenone
- Allergy to Spironolactone
Side Effects
Common: breast enlargement or tenderness in men, irregular periods or breast tenderness in women, dizziness, tiredness, stomach upset, diarrhoea, and leg cramps.
Get urgent medical help if you have:
- Muscle weakness, numbness or tingling, a slow or irregular heartbeat (signs of high potassium)
- Severe dizziness, fainting, confusion or very little urine (dehydration or kidney problems)
- Blistering or peeling skin, or swelling of the face, lips or throat
- Yellow skin or eyes
Pregnancy and Lactation
Not recommended in pregnancy because it can affect the sex development of the baby; it is used only if a doctor considers it essential. Women of childbearing age taking it for skin conditions should use contraception. A breakdown product passes into breast milk in small amounts; ask the doctor before breastfeeding.
Precautions and Warnings
- Regular blood tests for potassium, sodium and kidney function are needed.
- Do not use potassium supplements or salt substitutes unless the doctor says so.
- If you have vomiting or diarrhoea and cannot drink, contact the doctor, as the dose may need to be paused.
- Older people and people with diabetes or kidney disease are at higher risk of high potassium.
- It may cause dizziness; take care when driving.
Overdose
May cause drowsiness, confusion, nausea, vomiting, dizziness, dehydration and high potassium. Contact a doctor or hospital urgently.
Therapeutic Class
Potassium-sparing diuretic (aldosterone antagonist).
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.