Two hands and two pill bottles filled with water

Spironolactone: a Less-Known Diuretic

Last updated: October 2021

Many people with heart failure (HF) have experience with diuretics. Overall, diuretics help reduce some symptoms of heart failure, such as water retention. The most common diuretic used is furosemide, which goes by the brand name Lasix.

However, sometimes people are prescribed a different diuretic, such as spironolactone. What is interesting about spironolactone is that it is not just used for heart failure; it has many uses, including treating acne and hair loss.1 For the purpose of this article, we will talk about spironolactone for its use in HF.

What is spironolactone?

Spironolactone goes by the brand name Aldactone. Like Lasix, it reduces excess water from the body; however, its method of action to achieve this differs. Spironolactone may be trialled in people who don’t receive the intended benefit of furosemide.1 In addition to reducing excess fluid, spironolactone can:1

  • Be used to raise blood potassium levels
  • Lower blood pressure
  • Treat some kidney conditions

How is spironolactone taken?

Spironolactone is usually prescribed at the lowest dose of half of a 25 mg tablet to start. The drug can be taken with or without food.1 The best time to take it is in the morning so that it does not interfere with your sleep.

Who should not take this medication?

Overall, spironolactone has more contraindications than Lasix. A contraindication is a condition or a symptom that makes taking the drug dangerous, so the drug should be avoided in these cases.2 Contraindications of spironolactone include:1

  • If you have high potassium levels, or a condition that increases your risk of high potassium levels. This is because a side effect of spironolactone is increasing your blood potassium. Too much potassium can lead to irregular heart rhythms, also called dysrhythmias.
  • People on certain drugs, such as eplerenone or amiloride, which are also diuretics.
  • People with severe kidney disease.
  • Women who are pregnant or breastfeeding.

Required lab tests

If your doctor recommends that you start spironolactone, there are some important monitoring parameters required to ensure the drug is safe for you. Your doctor may monitor:

  • Your blood pressure readings
  • Blood potassium and sodium levels
  • Your kidney function
  • Whether you are still experiencing water retention


When taking spironolactone, there are a few things you should keep in mind:1

  • Do not take potassium supplements unless recommended by your doctor.
  • Use caution when driving, as some people may experience dizziness or drowsiness when on this medication. This caution only applies to the first few doses, so you can assess your response to the drug.
  • In some men, spironolactone may increase the risk of a condition known as gynecomastia, which is breast development. The risk of this increases with high doses and long treatments; however, it is most often reversible once the drug is stopped. If you experience this, inform your doctor right away.

There are a lot of diuretics that can be used to treat water retention in people with HF. Being knowledgeable about your diuretic can help you in your health journey. If you have any questions about your drug, the best person to ask is your pharmacist or physician. Do you take spironolactone? What has been your experience so far?

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This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

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