Spironolactone (Aldactone)

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Spironolactone is known as a water tablet.

It will make you go to the toilet more often to pass urine.

The most common side-effect is a mild stomach upset. This is not usually troublesome.

Type of medicine Aldosterone antagonist diuretic
Used for Fluid retention
Heart failure
Primary aldosteronism
Also called Aldactone®, Lasilactone® (spironolactone with furosemide), Aldactide® (spironolactone with hydroflumethiazide)
Available as Tablets

Spironolactone is used to treat oedema (fluid retention) caused by liver disease, kidney problems or heart failure. Oedema occurs when fluid leaks out of your blood vessels, causing swelling in the tissues of your lungs, feet or ankles. This makes you feel breathless and your legs feel puffy. Spironolactone prevents a build-up of fluid in your body by increasing the amount of urine your kidneys produce. It is also used to treat some other conditions causing too much fluid in the body, such as a disorder called primary hyperaldosteronism.

Spironolactone is known as a potassium-sparing diuretic. Unlike some other diuretics, it does not cause your body to lose potassium. Diuretics are sometimes referred to as 'water tablets'.

It is often used alongside other diuretics. When it is used like this, it may be prescribed as a combination tablet/capsule, such as in Lasilactone® (spinolactone with furosemide) and Aldactide® (spironolactone with hydroflumethiazide). Combinations like these help to reduce the number of tablets you need to take each day.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking spironolactone it is important that your doctor or pharmacist knows: 

  • If you are pregnant, trying for a baby or breast-feeding.
  • If you have kidney problems.
  • If you have a problem with your adrenal glands, called Addison's disease.
  • If you have porphyria (a rare inherited blood disorder).
  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • If you have ever had an allergic reaction to a medicine.
  • Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack. The leaflet will give you more information about spironolactone and a full list of side-effects which you may experience from taking it.
  • Take spironolactone exactly as your doctor has told you. The usual dose varies from 25 mg to 200 mg. Depending upon which dose is right for you, you may be asked to take several tablets a day but these are generally taken at the same time. Take the tablets with or just after a meal.
  • Spironolactone is commonly prescribed just once daily and you can generally take the dose at a time to suit you. However, diuretics are best taken no later than mid-afternoon. This is because you will find you may need to go to the toilet a couple of times after taking them and this may disturb your sleep if you take it late in the day. If you have been prescribed more than one tablet of spironolactone a day and told to take them at different times, make sure you take your last tablet no later than 6 pm.
  • If you forget to take a dose, take it as soon as you remember. However, if it is after 6 pm in the evening, skip the missed dose and continue as usual the next day. Do not take two doses at the same time to make up for a missed dose.
  • Try to keep your regular appointments with your doctor. This is so your doctor can check on your progress. The salt balance in your bloodstream may be upset by diuretics and your doctor will want you to have a blood test from time to time to check for this.
  • Diuretics help you to lose water, so you can breathe and move more easily. If, however, you lose too much fluid, you may become dehydrated. This will make you feel thirsty and make your skin look and feel dry. Let your doctor know if this happens, as your dose may need to be adjusted.
  • Because spironolactone is a potassium-conserving diuretic, you should try to avoid things with a high potassium content, such as 'salt substitutes'. This is so the level of potassium in your body does not become too high.
  • Treatment with diuretics is usually long-term, so continue to take these tablets unless you are advised otherwise.
  • If you buy any medicines, check with a pharmacist that they are suitable to take with your other medicines.
  • If you are having an operation or dental treatment, tell the person carrying out the treatment which medicines you are taking.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Spironolactone side-effects
What can I do if I experience this?
Stomach upset Stick to simple meals - avoid rich or spicy foods
Feeling tired, dizzy, or sleepy If this happens, do not drive or use tools or machines until you feel better
Sexual problems, breast discomfort and enlargement, feeling confused, irregular periods, confusion, sweating, cramps, hair loss, and skin rash If any of these become troublesome, speak with your doctor

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

Never take more than the prescribed dose. If you suspect that you or someone else has taken an overdose of this medicine, go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Further reading & references

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Dr John Cox
Document ID:
3360 (v23)
Last Checked:
05/04/2013
Next Review:
04/04/2016
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