What it is used for

Heart failure
Fluid build-up caused by liver disease, kidney problems or heart failure
High blood pressure that is hard to control
Primary hyperaldosteronism (Conn's syndrome)

Read our guides:

Off-label uses

Doctors sometimes prescribe a medicine for a condition it is not officially licensed for. This is called off-label use. It is legal and common when there is good evidence it helps, and your doctor should explain why they are suggesting it.

Acne in women
Excess hair growth (hirsutism), including in PCOS
Gender-affirming hormone treatment, under a specialist

How it works

Spironolactone blocks aldosterone, a hormone that makes the kidneys hold on to salt and water. Blocking it removes extra fluid while keeping potassium. It also blocks some effects of male hormones, which is why it can help with acne and excess hair.

Side effects

Like all medicines, Spironolactone can cause side effects, although not everyone gets them. Many are mild and ease after the first few weeks.

Common side effects

high potassium levels
breast swelling or tenderness
irregular periods
feeling dizzy
feeling sick
needing to pee more

Tell your doctor or pharmacist if these bother you or do not go away.

Serious side effects

These are rare. Call 111 or contact your doctor straight away if you get:

muscle weakness, numbness or an irregular heartbeat, which can be signs of high potassium
confusion, drowsiness or peeing much less
yellowing of the skin or eyes

Call 999 if you have signs of a serious allergic reaction, such as swelling of your lips, mouth, throat or tongue, or trouble breathing.

You can report any side effect to the Yellow Card scheme, run by the medicines regulator.

Stopping and withdrawal

Important safety information

You need regular blood tests to check potassium and kidneys.
Avoid potassium supplements and salt substitutes.
Pause it during sickness or diarrhoea if your doctor advises (sick day rules).

Questions about your medicine?

A pharmacist can answer questions about your medicines for free, without an appointment. You can also ask your GP for a medication review. Check if you can get free prescriptions.