What Is the Downside of Spironolactone? Understanding Risks and Side Effects

October 7, 2025 •

3 min read

According to a major study involving heart failure patients, about 10% of men taking spironolactone experienced gynecomastia, or breast enlargement, highlighting a significant and often dose-dependent hormonal side effect. Understanding what is the downside of spironolactone is crucial, as this medication's benefits must be weighed against its potential adverse effects, which range from electrolyte imbalances to major drug interactions.

Quick Summary

Spironolactone's downsides include a significant risk of hyperkalemia (high potassium), hormonal changes like breast enlargement and menstrual irregularities, and potential kidney problems. Drug interactions and less severe side effects, such as fatigue and dizziness, also need careful consideration.

Key Points

Hyperkalemia Risk: Spironolactone can cause dangerously high potassium levels, especially in older adults or those with kidney problems.
Hormonal Side Effects: The medication can cause breast enlargement (gynecomastia) in men and menstrual irregularities in women.
Required Monitoring: Regular blood tests are necessary to monitor potassium levels and kidney function.
Significant Drug Interactions: Combining spironolactone with NSAIDs, ACE inhibitors, or potassium supplements increases hyperkalemia risk.
Contraindicated in Certain Conditions: The drug should not be used by individuals with severe kidney disease, Addison's disease, or pre-existing high potassium.
Other Common Adverse Effects: Patients may experience fatigue, dizziness, gastrointestinal distress, and low libido.

Navigating the Primary Concerns: Hyperkalemia and Hormonal Impact

Spironolactone is a valuable medication used to treat various conditions, but it has notable downsides, primarily related to its effect on potassium levels and hormones. The risk of high potassium, or hyperkalemia, is a critical concern, particularly in older patients or those with kidney issues. The medication's antiandrogenic properties can also lead to unwanted hormonal effects, such as gynecomastia in men and menstrual irregularities in women.

The Risk of Hyperkalemia

Spironolactone is a potassium-sparing diuretic, meaning it can increase potassium levels in the body. While this can be helpful in some cases, it can lead to hyperkalemia. Individuals with kidney disease, diabetes, or those taking certain other medications are at higher risk. Symptoms of severe hyperkalemia can include muscle weakness, fatigue, or an irregular heartbeat. Regular blood tests are important to monitor potassium levels.

Hormonal and Endocrine Side Effects

As an androgen receptor antagonist, spironolactone can block the effects of male hormones. This can be beneficial for certain conditions but can also cause significant downsides. Gynecomastia (male breast growth) is a known side effect, which is often dose-dependent and can be painful. Men may also experience decreased libido and erectile dysfunction. Women might see changes in their menstrual cycle, including irregular periods or breakthrough bleeding. Other hormonal effects can include breast pain or tenderness.

Potential Impact on Kidney Function

Spironolactone is processed by the kidneys, and pre-existing kidney issues can increase the risk of hyperkalemia and other adverse effects. Some studies have indicated that kidney function may worsen in certain patients taking spironolactone. Beyond potassium, spironolactone can also affect other electrolytes, potentially leading to low sodium, magnesium, or calcium. Regular monitoring of kidney function through blood tests is necessary.

Significant Drug Interactions and Contraindications

Spironolactone can interact with other medications, increasing the risk of side effects. Combining it with ACE inhibitors, ARBs, or NSAIDs can increase the risk of hyperkalemia. Potassium supplements and salt substitutes containing potassium should also be avoided. Spironolactone can also affect the levels of certain medications like lithium.

Comparison: Spironolactone vs. Eplerenone

Eplerenone is a selective aldosterone blocker that may have fewer androgen-related side effects compared to spironolactone. The choice between these medications depends on individual factors.


Feature	Spironolactone	Eplerenone (Inspra)
Mechanism	Non-selective aldosterone and androgen blocker	Selective aldosterone blocker
Gynecomastia Risk	Higher incidence, especially at higher doses	Significantly lower risk
Sexual Side Effects	Decreased libido, erectile dysfunction possible	Less common
Cost	Generally lower-cost generic	More expensive
Potassium Risk	Significant risk of hyperkalemia, especially with other drugs	Still carries hyperkalemia risk, but interaction profile may differ

Conclusion: Balancing Risks and Benefits

Understanding what is the downside of spironolactone involves considering its hormonal, metabolic, and renal risks. While effective for various conditions, its antiandrogenic effects leading to gynecomastia and menstrual issues are important to note. The most significant risk is hyperkalemia, particularly with other medications or in vulnerable individuals. Close medical supervision, including regular monitoring of potassium and kidney function, is vital. Patients should discuss these potential downsides with their healthcare provider. Review research on spironolactone side effects.

Other Considerations and Less Common Side Effects

Beyond the main risks, other adverse effects can occur, such as gastrointestinal issues, dizziness, fatigue, and less frequently, severe skin reactions. Taking the medication with food might help with stomach problems. The need for regular blood tests is also a consideration. Personalized treatment and ongoing communication with healthcare providers are essential for anyone taking spironolactone.

Frequently Asked Questions

The most serious downside is hyperkalemia, or dangerously high potassium levels, which can cause severe heart rhythm problems. It is particularly risky for older patients and those with kidney issues.

Yes, gynecomastia (male breast growth) is a known side effect of spironolactone, caused by its antiandrogen properties. It is often dose-dependent and typically resolves after discontinuing the medication.

Spironolactone use can lead to worsening kidney function, especially in patients with pre-existing renal impairment. Regular blood tests are required to monitor kidney health while on this medication.

Common side effects include headache, dizziness, nausea, fatigue, and leg cramps. Taking the medication with food can sometimes help reduce stomach-related issues.

Avoid taking spironolactone with potassium supplements, NSAIDs like ibuprofen, and other medications that increase potassium, such as ACE inhibitors (e.g., lisinopril) and ARBs (e.g., losartan). Combining these can lead to severe hyperkalemia.

Many common side effects, such as dizziness and nausea, may lessen over time as your body adjusts. However, more serious side effects like hyperkalemia or hormonal changes may persist and require a dose adjustment or discontinuation of the drug.

Yes, spironolactone can cause menstrual irregularities in women, including irregular periods, breakthrough bleeding, or heavier bleeding. This side effect is more common at higher doses.