Spironolactone: 7 things you should know

Medically reviewed by Carmen Pope, BPharm. Last updated on Jan 3, 2024.

1. How it works

• Spironolactone is a medicine used in a variety of heart-related and fluid-retaining conditions. It is also used for the diagnosis and management of primary hyperaldosteronism (a condition where the adrenal glands produce too much of the hormone aldosterone leading to low potassium levels and a more alkaline blood pH).
• Spironolactone inhibits the action of aldosterone by binding to specific receptors in the kidney where aldosterone controls the balance of salt and water in the body. Blocking aldosterone increases the excretion of sodium and other salts through the kidney into the urine. As these salts leave the body, water is also drawn alongside. Through this mechanism, spironolactone removes excess fluid from the body and also has a blood pressure-lowering effect.
• Spironolactone belongs to the class of medicines called aldosterone receptor antagonists. Spironolactone may also be called a potassium-sparing diuretic.

2. Upsides

• Removes excess fluid from the body and may be used in the treatment of heart failure, cirrhosis of the liver, and nephrotic syndrome (a type of kidney disease). Has been shown to increase survival and reduce the need for hospitalization in people with severe heart failure.
• May be used in the treatment of high blood pressure (hypertension) in conjunction with other medications and lifestyle measures (such as lipid control, diabetes management, smoking cessation, blood thinning medications, exercise, and a reduction in sodium intake). Reducing blood pressure is associated with an improvement in survival in people with cardiovascular disease.
• May be used in the diagnosis or treatment of primary hyperaldosteronism (a hormonal disorder characterized by the over-production of aldosterone that leads to high blood pressure).
• May be used long-term in some people with inoperable aldosterone-producing tumors.
• May occasionally be used to treat hypokalemia (low potassium levels) when other treatments are inappropriate or ineffective.
• Spironolactone does not cause potassium loss nor is it likely to precipitate gout, unlike several other diuretics.
• Generic spironolactone is available.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• Gynecomastia (enlargement of a man's breasts) is reported by approximately 13% of men who take spironolactone. The risk is higher with higher dosages of spironolactone and a longer duration of therapy. The gynecomastia usually reverses once spironolactone is discontinued.
• May cause low sodium levels (hyponatremia), low magnesium levels (hypomagnesia), lowered testosterone levels, and high potassium levels (hyperkalemia). Low calcium levels and high blood sugar levels may also occur. Nausea, vomiting, tiredness, changes in menstruation, libido, hair loss, and postmenopausal bleeding may also occur.
• Rarely, may cause drowsiness or dizziness and affect a person's ability to drive or operate machinery.
• May interact with several other drugs including those that also retain potassium (such as ACE inhibitors), lithium, NSAIDs, and digoxin.
• Not suitable for people with certain kidney problems, Addison's disease, or high potassium levels. Should be used with caution in people with other electrolyte disturbances, and in women who are pregnant or breastfeeding. Animal studies have reported the feminization of male fetuses and endocrine dysfunction in females exposed to spironolactone in utero. Animal studies have also shown that the use of spironolactone is associated with a higher risk of cancer of the endocrine organs (such as the thyroid) and liver. People with diabetes may need their blood sugar levels monitored more frequently.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Spironolactone is a diuretic that may be used to remove excess fluid (edema) from the body, lower blood pressure, or treat hyperaldosteronism. It does not cause potassium loss from the body; however, other electrolytes may become depleted.

5. Tips

• May be taken with or without food. Take with food if stomach upset occurs.
• Tell your doctor if you experience any intolerable side effects, such as excessive thirst, drowsiness, muscle pains or cramps, and in men, enlarged breasts.
• Avoid taking salt substitutes that contain potassium or potassium supplements while taking spironolactone. Try to avoid foods high in potassium (such as avocados, bananas, coconut water, spinach, and sweet potato) because eating these foods may lead to potentially fatal hyperkalemia (high blood potassium levels).
• Do not drive or operate machinery if spironolactone makes you drowsy or impairs your judgment.
• Your doctor may need to periodically monitor electrolyte levels in your blood while you are taking spironolactone.
• Tell your doctor if you are pregnant, intend to become pregnant, or are breastfeeding.

6. Response and effectiveness

• Spironolactone is metabolized into active sulfur-containing substances, and peak concentrations are reached within three to five hours. The effects of one dose of spironolactone usually last for 24 hours.

7. Interactions

Medicines that interact with spironolactone may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with spironolactone. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with spironolactone include:

• alpha/beta-agonists such as epinephrine
• ammonium chloride
• amphetamines
• antipsychotics (may enhance the blood pressure-lowering effect), such as clozapine, haloperidol, or chlorpromazine
• aspirin
• atorvastatin
• blood pressure-lowering agents such as beta-blockers (atenolol or sotalol)
• ciprofloxacin
• cyclosporine
• digoxin
• duloxetine
• erectile dysfunction medications, such as sildenafil or tadalafil
• heparin
• levodopa-containing products
• lithium
• methylphenidate
• NSAIDs, such as diclofenac, ibuprofen, or indomethacin
• opioids, such as fentanyl, morphine, or oxycodone
• pholcodine
• potassium salts
• quinidine
• tacrolimus
• trimethoprim
• other medications that increase potassium, such as ACE inhibitors, ARBs, or amiloride.

People taking oral medications for diabetes may need to talk to their doctor about adjusting the dose of their medicine.

Note that this list is not all-inclusive and includes only common medications that may interact with spironolactone. You should refer to the prescribing information for spironolactone for a complete list of interactions.

References

• Spironolactone. Revised 12/2023. Accord Healthcare Inc. https://www.drugs.com/pro/spironolactone.html

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use spironolactone only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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