13 Spironolactone (Aldactone) Side Effects to Consider

Spironolactone (Aldactone) is an older medication, originally approved by the FDA in 1960. It belongs to a group of medications called mineralocorticoid receptor antagonists.

Spironolactone works by blocking a hormone called aldosterone. This hormone helps balance certain electrolytes, blood volume, and blood pressure. Spironolactone is also a type of diuretic (“water pill”). This means it removes extra fluid from the body through urination. These actions make this medication helpful for several different health conditions.

Even though spironolactone has been around for a long time, it’s still commonly prescribed today. However, there are some notable side effects of spironolactone to know about.

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What is spironolactone used for?

Spironolactone is FDA approved to treat a few health conditions:

• Heart failure with reduced ejection fraction

• High blood pressure when prescribed with other medications

• Swelling caused by fluid buildup (edema), often due to liver or kidney damage

• Primary hyperaldosteronism, a condition where the body makes too much of the hormone aldosterone

Spironolactone is also sometimes prescribed for other conditions in ways that aren’t FDA approved. This is called “off-label” use. Common off-label uses for spironolactone include:

• Acne

• Polycystic ovary syndrome (PCOS)

• Hirsutism (male-pattern hair growth in women)

• Part of estrogen-based gender-affirming hormone therapy (GAHT)

• After having a heart attack

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Spironolactone side effects at a glance

Like all medications, spironolactone has side effects. Many are mild and get better or go away as your body adjusts to the medication. Others are more serious and warrant medical attention.

Common spironolactone (Aldactone) side effects include:

• Mildly higher blood potassium levels

• Mildly low blood sodium levels

• Breast pain or tenderness

• Muscle cramps, especially in the legs

• More pronounced feminine characteristics, such as breast growth

• More frequent urination

• Irregular menstrual cycles

• Decreased libido (sex drive)

• Erectile dysfunction

• Fatigue

• Dizziness

• Headache

• Nausea

• Vomiting

• Diarrhea

Severe spironolactone (Aldactone) side effects include:

• Severely high blood potassium levels

• Severely low blood sodium levels

• Dehydration

• Stomach bleeding or ulcers

• Confusion

• Loss of balance

• Skin rashes

• Kidney problems

Below, we’ll review 13 notable spironolactone side effects.

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1. High potassium levels

Spironolactone can cause high blood potassium (hyperkalemia). Your prescriber will likely check your potassium regularly while you’re taking spironolactone to make sure it’s not too high. If your potassium levels rise too much, your spironolactone dosage may need to be lowered or stopped.

High potassium is a common spironolactone side effect. It’s usually mild and symptom-free. But it can become serious for some people. In severe cases, it can cause heart rhythm problems. Symptoms of high potassium can be mild and easily missed. So, it’s best to follow your prescriber’s instructions for getting blood tests done while taking spironolactone.

People who have health conditions that cause high potassium, such as Addison’s disease, should avoid spironolactone. This is because they’re more likely to develop severely high potassium. Some people with kidney problems may need to avoid spironolactone as well.

High potassium levels are also more likely to happen if you take certain medications. This includes some common blood pressure medications and nonsteroidal anti-inflammatory drugs (NSAIDs). Make sure to share your current medication list with your healthcare team. They’ll be able to tell you if it’s safe to take spironolactone along with your other medications.

2. Breast tenderness

Breast tenderness is usually a mild spironolactone side effect. But it can be frustrating and uncomfortable. Wearing loose-fitting shirts or a more supportive bra may help with breast pain. Applying warm or cool compresses to the area can also be soothing. Be aware that breast tenderness can happen to both men and women taking spironolactone.

Let your prescriber know if you experience this side effect. Sometimes, taking a lower dose of spironolactone will help. Other times, you may need to stop the medication to relieve this side effect.

3. Muscle cramps (especially in the legs)

Spironolactone can also cause muscle cramps, particularly in the legs. Many people find this to be most noticeable at night while sleeping. This spironolactone side effect is likely caused by changing fluid and electrolyte levels.

Leg or other muscle cramps should get better or go away after your body adjusts to spironolactone. Staying hydrated, massaging your muscles, and taking hot showers can help relieve cramps. If cramps become bothersome or seem severe, contact your prescriber for next steps.

4. More pronounced feminine characteristics

Spironolactone can lower testosterone production throughout the body. This can cause the development of feminine characteristics for some people taking it. One example is male breast growth (gynecomastia). This may be a desired effect of the medication if it's being taken as part of GAHT. But for people not taking spironolactone for GAHT, breast growth can be upsetting.

These side effects usually lessen or go away if your dose is lowered. There may also be alternative treatments for your condition. Let your prescriber know if you experience these effects and they’re unwanted.

5. Urinating more than usual

All diuretics, including spironolactone, can cause you to urinate more than usual. While this is helpful for removing extra fluid, it can be annoying. It may be most noticeable right after you start the medication or following a dose increase.

Many people take spironolactone once a day. In this case, consider taking your dose in the morning. This can help prevent you from waking overnight to use the bathroom.

If this side effect becomes too bothersome or seems excessive, let your healthcare team know. Depending on why you’re taking spironolactone, there may be other options to treat your health condition.

6. Decreased sex drive

Loss of libido can also happen due to spironolactone’s effects on testosterone. Some people may also experience erectile dysfunction (ED).

Libido usually improves on lower doses of spironolactone or after it’s stopped. Your prescriber may also recommend ED treatments if spironolactone seems to be working well for you otherwise.

7. Irregular menstrual cycles

Irregular menstrual cycles are a common side effect when taking spironolactone for acne. This can include breakthrough bleeding, heavier bleeding, or no bleeding. This side effect is more common with higher doses.

There are a few ways to help manage this spironolactone side effect besides lowering your dose. Sometimes, oral birth control pills can help regulate your cycle. Your prescriber may also tell you to take spironolactone for 3 weeks and then take 1 week off. Ask your prescriber which option may be right for you.

8. Dehydration

Like other diuretics, spironolactone helps the body get rid of excess fluid. But if too much fluid is lost, you can get dehydrated. Symptoms of dehydration include feeling thirsty, headaches, and dark-colored urine.

Drinking plenty of water can help you avoid dehydration. But if you have heart failure, discuss how much water is safe for you to drink per day with your healthcare team.

9. Low sodium

Spironolactone can cause loss of sodium through the urine. This can lead to low blood sodium (hyponatremia). Similar to high potassium, low sodium is a common side effect that can become serious. You’ll likely have your sodium levels checked regularly with blood tests while taking spironolactone.

Depending on how low your sodium level is, your prescriber may ask you to make dietary changes to try to balance it out. But if your sodium drops too low, you may need to stop taking spironolactone. Be sure to go for all blood tests whenever your prescriber recommends them.

10. Fatigue

Like other blood pressure medications, spironolactone can cause fatigue (tiredness). This often happens shortly after starting it or raising your dose. Fatigue may be your body’s response to changes in blood pressure or electrolyte levels.

In most cases, tiredness will improve as your body adjusts to taking spironolactone. If fatigue seems severe or doesn’t seem to get better, let your prescriber know.

11. Stomach-related side effects

Stomach-related side effects are also possible with spironolactone. These may include nausea, diarrhea, or vomiting. Sometimes, these side effects can happen from taking spironolactone on an empty stomach. Taking it with food might help.

If you find stomach-related side effects to be bothersome or severe, let your healthcare team know. In rare cases, spironolactone can cause stomach bleeding. Your prescriber may want to evaluate you for this if you’re having severe or excessive stomach-related side effects.

12. Central nervous system problems (dizziness, headache, confusion)

The central nervous system (CNS) includes the brain and spinal cord. CNS-related side effects with spironolactone can include headaches, dizziness, and confusion. Some people also report they have trouble balancing or walking properly. Keep in mind that these CNS issues can also be symptoms of hyponatremia or hypotension. It can be hard to tell what’s causing them.

CNS side effects can be concerning. They can also raise your risk of falling or accidentally hurting yourself. You should let your prescriber know if you experience any CNS side effects while taking spironolactone.

13. Skin rash

Skin rashes from spironolactone can be mild, but they can also be severe. Severe skin reactions, such as Stevens-Johnson syndrome, can be life-threatening. If you develop a skin rash while taking spironolactone, contact your prescriber right away (even if it seems mild). If your rash is widespread or appears along with other symptoms, such as fever or blistering, seek emergency help right away.

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Written by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

Edited by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

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