Sounds like 'spir-ON-oh-LAK-tone'

Easy-to-read medicine information about spironolactone – what it is, how to take it safely and possible side effects. Spironolactone is commonly called Spiractin or Spirotone.

Type of medicine Also called
  • Diuretic (causes you to pee more)
  • ‘Water tablet’ or ‘water pill’
  • Potassium-sparing diuretic
  • Spiractin®
  • Spirotone®

What is spironolactone?

Spironolactone is used to treat a number of different conditions and related symptoms, including the following.

  • To reduce extra fluid in your body (called oedema) caused by conditions such as heart failure, liver disease or problems with your kidneys. It can reduce swelling in your ankles or feet, and shortness of breath.
  • High blood pressure (hypertension).
  • Primary hyperaldosteronism – in hyperaldosteronism, your adrenal glands produce too much of a hormone called aldosterone. Spironolactone works by stopping the effects of aldosterone.
  • Facial hair growth and acne in women, as in polycystic ovary syndrome (PCOS).


  • In New Zealand spironolactone is available as tablets (25 mg and 100 mg).
  • The dose of spironolactone will be different for different people depending your medical condition and response to treatment.
  • Always take your spironolactone exactly as your doctor has told you.
  • The pharmacy label on your medicine will tell you how much spironolactone to take, how often to take it and any special instructions.

How to take spironolactone

  • Timing: Spironolactone is usually taken once a day, in the morning. Some people taking higher doses may need to take a second dose later in the day. You can take spironolactone with or without food.
  • Limit or avoid alcohol while taking spironolactone: Alcohol may increase your chance of side effects such as dizziness.
  • Missed dose: If you forget to take your dose, take it as soon as you remember that day. If it is nearly time for your next dose, skip the missed dose and take your next dose at the usual time. Do not take 2 doses at the same time.

Precautions when taking spironolactone

Before starting spironolactone

  • Are you pregnant or breastfeeding?
  • Do you have problems with your kidneys?
  • Do you have Addison’s disease?
  • Are taking any other medicines? This includes any medicines you are taking that you can buy without a prescription, as well as herbal and complementary medicines and medicines you can buy for pain relief.

If so, it’s important that you tell your doctor or pharmacist before you start spironolactone. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

While taking spironolactone

You may need blood tests while taking spironolactone to check the amount of potassium and sodium in your blood, and to see how well your kidneys are working.

What are the side effects of spironolactone?

Like all medicines, spironolactone can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

High potassium levels in your blood

Spironolactone can cause high potassium levels in your blood (also called hyperkalaemia). You are at increased risk of hyperkalaemia if you:

You will need blood tests while you are taking spironolactone to check the amount of potassium in your blood, especially when you first start spironolactone, during dose changes or if you become unwell with any illness that affects your kidneys.

Try to avoid things with a high potassium content, such as salt substitutes or low-sodium salt. This is so the level of potassium in your body does not become too high.

Contact your doctor immediately or phone Healthline 0800 611 116 if you develop signs of too much potassium in your blood, such as irregular heart beat (heart beat feels fluttery), tingling feelings, paralysis (difficulty moving) or difficulty breathing.

Other side effects

Side effects What should I do?
  • Feeling sick (nausea)
  • Stomach upset

  • These are quite common when you first start taking spironolactone and usually go away after the first few days.
  • Try taking your spironolactone dose with or after food.
  • Tell your doctor if troublesome.
  • Dizziness
  • Feeling light headed
  • Feeling faint when you stand up
  • Be careful when getting up from either lying down or sitting to avoid falls.
  • These effects puts you at risk of falls and injuries, especially if you are elderly.
  • Be careful when driving or using tools until you know how this medicine affects you.
  • Signs of too much potassium in your blood such as irregular heart beat (heart beat feels fluttery), tingling feelings, paralysis (difficulty moving) or difficulty breathing 
  • Spironolactone may cause increased potassium in your blood.
  • Tell your doctor immediately or phone Healthline 0800 611 116.
  • Signs of dehydration (losing too much salt and water) such as muscle cramps, weakness, dry mouth, thirst or passing unusually reduced amounts of pee
  • Tell your doctor immediately or phone Healthline 0800 611 116.
  • Signs of hormone changes such as breast development (in men), changes in menstrual cycle (periods) in women or sexual function problems   
  • Tell your doctor.
Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product


Spironolactone may interact with a number of medicines and herbal supplements so check with your doctor or pharmacist before starting spironolactone and before starting any new medicines.

Also check with your pharmacist before taking anti-inflammatories that can be bought over the counter, such as diclofenac (eg, Voltaren Rapid), ibuprofen (eg, Nurofen), naproxen (eg, Naprogesic).

Learn more

The following links provide further information on spironolactone:

Spiractin Medsafe Consumer Information Sheets, NZ
Spironolactone (Māori) NZ Formulary Patient Information


  1. Spironolactone NZ Formulary
  2. Reminder – hyperkalaemia caused by amiloride or spironolactone Medsafe Prescriber Update, NZ, 2021 

Additional resources for healthcare professionals

Interactions checker NZ Formulary
Spiractin Medsafe, NZ
Managing patients with heart failure in primary care BPAC, NZ, 2013
Hypertension in adults – the silent killer BPAC, NZ, 2013

Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 20 Sep 2021