MedicinePOMEssential

Spironolactone

A diuretic ('water tablet') for fluid build-up, heart failure and high blood pressure.

Clinical information

Common uses

swelling from fluid build-up (oedema)
heart failure
high blood pressure when other medicines have not worked

Common side effects

feeling dizzy
feeling sick
muscle or leg cramps
tiredness or low energy
breast pain or enlargement, including in men

Cautions

not suitable with severe kidney problems or Addison's disease
can raise potassium levels (hyperkalaemia)
avoid potassium-rich salt substitutes like Lo-Salt
not suitable if you have had high potassium before

Interactions

digoxin (heart medicine)
eplerenone and some blood pressure or heart failure medicines
potassium supplements
NSAIDs such as ibuprofen, aspirin, diclofenac

Pregnancy: not usually recommended — may affect baby's development

Reference information, not medical advice — always follow your doctor or pharmacist. Source: NHS Medicines A–Z, nhs.uk/medicines/spironolactone (accessed 2026-08-16)

Approved brands & formulations7

Brand name	Dosage form	Strength	Importer	Category
Aldactone	Tablet ( Uncoated Tablet )	25 mg	authorized medicine importers	POM
Aldactone 100	Tablet	100 mg	authorized medicine importers	POM
Aldactone 100	Tablet ( Uncoated Tablet )	100 mg	authorized medicine importers	POM
Aldactone 25	Tablet	25 mg	authorized medicine importers	POM
Spironolactone	Tablet ( Uncoated Tablet )	100 mg	—	POM
Spironolactone	Tablet ( Uncoated Tablet )	25 mg	—	POM
Spironolactone	Tablet	50 mg	—	POM