Aldactone (spironolactone) is a prescription oral tablet used for high blood pressure, heart failure, and other conditions. Aldactone can cause side effects that range from mild to serious. Examples include high blood potassium and breast swelling.

Specifically, Aldactone is used in adults to treat:

The active ingredient in Aldactone is spironolactone. (An active ingredient is what makes a drug work.)

Keep reading to learn about the common, mild, and serious side effects Aldactone can cause. For a general overview of the drug, including details about its uses, see this article.

Some people, but not all, may experience mild to serious side effects during Aldactone treatment. Examples of the drug’s commonly reported side effects include:

* In this article, we use the term “male” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.
† To learn more about this side effect, see the “Side effects explained” section below.

Mild side effects have been reported with Aldactone. These include:

In most cases, nausea, vomiting, stomach cramps, diarrhea, dizziness, and drowsiness should be temporary. Other side effects, such as irregular periods or headaches, may be easily managed. But if you have ongoing or bothersome symptoms, talk with your doctor or pharmacist. And do not stop taking Aldactone unless your doctor recommends it.

Aldactone may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

* In this article, we use the term “male” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.
† To learn more about this side effect, see the “Side effects explained” section below.

Serious side effects have been reported in Aldactone studies. These include:

If you develop serious side effects while taking Aldactone, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

* To learn more about this side effect, see the “Side effects explained” section below.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Aldactone, visit MedWatch.

Get answers to some frequently asked questions about Aldactone’s side effects.

Are there long-term side effects from Aldactone use?

Although scientists previously believed that Aldactone might increase the risk of cancer, a recent expert review of studies showed no significant cancer risk increase. Researchers actually discovered Aldactone may reduce the risk of prostate cancer.

However, these studies did not include people under the age of 18 years (who typically take Aldactone for acne and hair loss). So more studies may need to be completed in this age group to better determine the possibility of long-term side effects from Aldactone.

Overall, experts believe long-term use of Aldactone is safe for most people.

Are side effects of Aldactone seen in females* different than those seen in males*?

In studies, approximately 1 out of every 10 males developed painful or enlarged breasts from Aldactone. This condition is called gynecomastia and is reversible by lowering the dose or stopping the medication.

Additionally, some men may be unable to attain or maintain an erection.

In females, an irregular menstrual period, no menstrual period, or vaginal bleeding after menopause may develop while taking Aldactone. These side effects may be easily managed with prescription birth control or hormone replacement.

Talk with your doctor if you have any of these side effects and do not stop taking this medication without their recommendation.

* In this article, we use the terms “male” and “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

Will Aldactone 25 mg cause fewer side effects than Aldactone 100 mg?

Yes, as the dose of Aldactone increases, the risk of side effects increases. The length of time you take Aldactone may also increase your risk of side effects.

However, severe side effects can still occur with a 25-mg dose, depending on your health status, drug interactions, and hydration level. It’s best to check with your doctor or pharmacist to help you evaluate your own personal risk factors.

Learn more about some of the side effects Aldactone may cause.

High potassium blood levels

High potassium blood levels were an occasional side effect reported in studies of Aldactone. High potassium blood levels may cause symptoms such as:

Factors that can increase the risk of high potassium blood levels when taking this drug include:

* In this article, we use the term “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

What might help

Your doctor will order a potassium blood test for you within 1 week of you starting Aldactone. And they’ll likely continue this testing at regular intervals throughout your treatment. This is especially important for people over the age of 45 years or those with low kidney function.

Before starting this medication, talk with your doctor or pharmacist. They can review the other drugs you take for potential interactions with Aldactone. If necessary, they may be able to recommend different treatment options that won’t interact with Aldactone.

Most importantly, if you have symptoms of high potassium blood levels during Aldactone treatment, talk with your doctor right away. High blood potassium can cause sudden heart attack or stroke. Your doctor will likely recommend an urgent medical evaluation.

Breast swelling in males

Gynecomastia (breast swelling in males*) was the most common side effect reported in studies of Aldactone. This side effect may cause symptoms such as:

  • enlarged breasts
  • breast tenderness
  • breast discharge

Factors that can increase the risk of breast swelling with Aldactone include the dose and how long the drug is taken. A lower dose for a longer time or a higher dose for a shorter time may increase your risk. And an even higher risk could occur with a higher dose for a longer time. Some people reported developing swollen breasts after 2 years of a low (25-mg) daily dosage.

What might help

If you develop swollen breasts during Aldactone treatment, talk with your doctor as soon as possible. They’ll likely suggest switching you to another drug called eplerenone. Swelling may take approximately 1 month to resolve after stopping Aldactone.

For temporary relief of pain and swelling you can try:

  • applying cool compresses
  • wearing a breast binder for support
  • showering or bathing with lukewarm water

You may also have pain relief with over-the-counter (OTC) acetaminophen. OTC nonsteroidal anti-inflammatories (NSAIDs), such as ibuprofen, aspirin, and naproxen are not recommended with Aldactone.

* In this article, we use the term “male” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

Allergic reaction

Like most drugs, Aldactone can cause an allergic reaction in some people. Symptoms can be mild to serious and can include:

  • skin rash, which may be severe and cover the body
  • itchy welts on the skin
  • blisters
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin (usually in your eyelids, lips, hands, or feet)

Life threatening allergic reactions requiring immediate medical evaluation have occurred in studies. These reactions include:

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

  • an oral antihistamine, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Aldactone, they’ll decide if you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Aldactone, they may have you switch to a different treatment.

Keeping track of side effects

During your Aldactone treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help them learn more about how Aldactone affects you. They can then use this information to adjust your treatment plan if needed.

Below is important information you should consider before taking Aldactone.

Warnings

Aldactone can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Aldactone is a good treatment option for you.

Talk with your doctor about your health history before starting Aldactone. Be sure to tell them if any of the following apply to you:

* To learn more about this side effect, see “Allergic reaction” in the “Side effects explained” section above.

Alcohol and Aldactone

There are no known interactions between alcohol and Aldactone. But alcohol may worsen side effects caused by Aldactone. These include dizziness, drowsiness, nausea, vomiting, headache, and dehydration.

If you have questions about consuming alcohol during Aldactone treatment, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Aldactone

If you’re able to become pregnant, consider the following information.

Pregnancy

Aldactone is usually only prescribed for a pregnant person if the benefits of treatment outweigh the potential risks to the fetus. Aldactone may affect the development of a male* fetus because of its ability to block male sex hormones.

If you’re able to become pregnant, your doctor may recommend using a form of birth control during your Aldactone treatment.

If you’re pregnant or planning to become pregnant, talk with your doctor about your treatment options.

Breastfeeding

Despite the lack of available research, it’s known that only low amounts of Aldactone’s metabolites (broken down parts) pass into breast milk. So the NIH Drugs and Lactation Database lists Aldactone as generally safe to take while breastfeeding.

Still, if you’re breastfeeding or planning to do so, talk with your doctor before starting Aldactone treatment.

* In this article, we use the term “male” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

Like most drugs, Aldactone can cause side effects that range from mild to serious. If you have questions about side effects this drug can cause, talk with your doctor. Examples of questions to help get you started include:

  • What are Aldactone’s most common side effects, and how do I reduce my risk?
  • With my health conditions, what side effects can I expect with Aldactone?
  • Which medications or foods should I avoid while taking Aldactone?
  • If I notice side effects with Aldactone, should I stop taking it?
  • Are life threatening side effects possible with Aldactone?

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Disclaimer: Healthline has made every effort to make sure that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.