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What is spironolactone?

Spironolactone is an aldosterone antagonist, meaning it blocks aldosterone receptors, leading to the excretion of water and sodium from the body. It is a potassium-sparing diuretic used primarily to treat heart failure and high blood pressure.¹

Spironolactone works by increasing the frequency of urination to resolve the excess fluid buildup that develops in people with certain medical conditions, such as liver failure, nephrotic syndrome, and congestive heart failure.

This medication is most commonly prescribed to reduce symptoms of heart failure and high blood pressure. Since high blood pressure is linked to many heart conditions, spironolactone can improve overall health by effectively treating several related symptoms.²

What is spironolactone used to treat?

Spironolactone has been approved by the US Food and Drug Administration (FDA) for the following indications:³

  • Heart failure, specifically NYHA Class III-IV heart failure, often in combination with other medications

  • Hypertension, when other drugs have failed to produce significant improvement and as part of a comprehensive cardiovascular risk management plan of therapy

  • Edema, in cases of liver cirrhosis and nephrotic syndrome that are unresponsive to other therapies

  • Primary hyperaldosteronism, as a short-term therapy for the preoperative treatment of patients with primary hyperaldosteronism and as a long-term maintenance therapy for people with:

    • Aldosterone-producing adrenal adenomas when surgery is not an option

    • Bilateral micronodular or macronodular adrenal hyperplasia

Spironolactone is sometimes prescribed off-label to help treat acne and hirsutism occurring alongside polycystic ovary syndrome, but these uses have not yet been approved by the US FDA.⁴

Dosage forms and strengths

Spironolactone is available in tablet and liquid forms in the following strengths:⁵

  • Tablets (generic, Aldactone): 25mg, 50mg, and 100mg 

  • Liquid (CaroSpir): 25mg/5mL 

Dosing depends on the condition being treated as well as the age and sex of the patient. When deciding the appropriate dose, your doctor will consider your medical history, other drugs you’re taking, and your body’s response to previous treatments. In most cases, doctors prescribe a low dose of spironolactone and increase the amount gradually as needed.

How do you take spironolactone?

Spironolactone may be taken one or more times daily, always at approximately the same times. Many people time their doses early in the day to minimize sleep disruption linked to increased frequency of urination. The drug can be taken with food or milk if it causes an upset stomach.

Liquid spironolactone should be shaken before each dose and measured carefully. 

Seeing results

Spironolactone starts working quickly, and the drug reaches peak concentrations in the blood within just a little over two hours.

One study focusing on morbidity and mortality rates of patients with severe heart failure taking spironolactone found the drug to be so effective by these measures so quickly that they discontinued follow-up earlier than planned.⁶ ⁷

You may not feel any different if you take spironolactone for high blood pressure because the condition often doesn’t cause symptoms. However, feeling the same doesn’t indicate spironolactone is not working. When you begin treatment, your doctor will monitor your blood pressure frequently to determine how well the medication works for you.⁸

If you take spironolactone for heart failure or edema, you may begin to breathe more easily, notice decreased swelling, have more energy, and see your overall health improve within just a few days.

Who should not take spironolactone?

You should speak with your doctor about whether spironolactone is right for you. Generally, spironolactone is not recommended for patients with the following:⁹

  • Known hypersensitivity to spironolactone or its ingredients

  • Addison’s disease or other conditions associated with high potassium levels

  • Severe kidney disease

  • Irregular menstrual cycles

  • Prostate cancer

  • Pregnancy

Additionally, the drug is prescribed cautiously for people with the following conditions:

Potential side effects of spironolactone

Taking spironolactone can trigger a range of side effects, including the following:¹⁰

  • Upset stomach, nausea, or vomiting

  • Dizziness or lightheadedness

  • Drowsiness

  • Headache

  • Increased thirst

  • Breast or nipple pain, gynecomastia

  • Hair loss

  • Leg cramps

  • Abdominal cramping, diarrhea

  • Menstrual changes

  • Rash, itching

  • Erectile dysfunction

Most people taking spironolactone won’t experience severe side effects, but certain symptoms can indicate life-threatening adverse effects. Signs of a severe complication may include any of the following:

  • Changes to your mood or mental health

  • Mental confusion, coma

  • Severe fatigue

  • Gait imbalance 

  • Muscle weakness   

  • Gastric bleeding, vomit that looks like coffee grounds

  • Severe, peeling skin rash

  • High potassium levels and other electrolyte abnormalities

  • Hypotension

  • Slow or irregular heartbeat

If you notice any signs of a severe adverse event, seek urgent medical attention. If you experience mild side effects that persist beyond a few days or weeks, schedule an appointment with your doctor.

Overdose

Call your doctor’s office or the Poison Control helpline if you take more than your prescribed dose of spironolactone. Taking a little bit too much may not trigger life-threatening symptoms, especially if your prescribed dose is low. However, an overdose of spironolactone can be a medical emergency.

Signs and symptoms of a drug overdose may include any of the following:

  • Difficulty breathing

  • Drowsiness

  • Nausea

  • Vomiting

  • Dizziness

  • Loss of consciousness

Contact 911 or go to your nearest emergency department if you or someone in your care has taken too much spironolactone and experiences severe symptoms.

Allergy information

Rarely, a person may be allergic to spironolactone. Symptoms that may indicate an allergic reaction include:

  • Itching or swelling (particularly serious if it affects the face, throat, or tongue)

  • Severe skin rash

  • Vomiting

  • Trouble breathing

  • Severe dizziness

  • Loss of consciousness

Seek urgent medical attention if you notice signs of an allergic reaction while taking spironolactone.

Long-term use of spironolactone

Spironolactone is generally safe to take long-term. It tends to become more effective over time for many patients. However, in rare cases of long-term use, spironolactone can cause gynecomastia.¹¹

Your doctor will monitor how well your medication works for you and may adjust your dosage with time, especially as you reach your senior years.

Pregnancy category

The US FDA classified spironolactone as a pregnancy category C drug, which means there are potential risks associated with taking the drug during pregnancy that cannot be ruled out. While the benefits often outweigh the risks in this category, category C medications do not have enough human studies to demonstrate the effects of the drug on human fetuses. Some animal studies may have shown negative outcomes.¹²

Spironolactone and pregnancy

Spironolactone should generally be avoided during pregnancy and while trying to become pregnant unless it is essential and no alternative options are available. This medication has the potential to influence certain male hormones, which can lead to abnormalities in male infants if taken during pregnancy.

Spironolactone and breastfeeding

Spironolactone has not been found in breast milk, but small amounts of the active metabolite, canrenone, have been detected. However, data is limited, and the long-term implications are unknown.

Missed doses

If you missed a dose of spironolactone, take it as soon as you remember. However, if it’s nearly time for your next dose, skip the missed one and resume your regular dosing schedule.¹³ ¹⁴

Drug interactions

Spironolactone can affect your body’s handling of other drugs. This is particularly true in the case of drugs that can lead to high potassium.

The following drugs taken in conjunction with spironolactone may cause adverse side effects:¹⁵

  • Other diuretics, such as amiloride (Midamor), triamterene (in Dyazide, Maxzide)

  • Blood pressure medicines like eplerenone (Inspra), captopril (Capoten), lisinopril (Zestril), and valsartan (Diovan)

  • Antidepressants, including isocarboxazid (Marplan)

  • Potassium-containing medications or supplements

  • Lithium

  • Immunosuppressants, such as cyclosporine (Sandimmune, Neoral) and tacrolimus (Prograf)

  • Anti-inflammatories like meloxicam (Mobic), naproxen (Aleve, Naprosyn), and ibuprofen (Motrin)

  • Cancer medicines like abiraterone (Zytiga) and clofarabine (Clolar)

  • Pain medications, including hydrocodone (Vicodin, Lortab), oxycodone (OxyContin), and meperidine (Demerol)

  • Sedatives such as alprazolam (Xanax) and midazolam (Versed)

  • Antiarrhythmics like propafenone (Rythmol)

  • Cholesterol medicines, such as simvastatin (Zocor)

This list of possible interactions is not exhaustive. Speak with your doctor about all medications you take regularly or occasionally.

Can I drink alcohol while taking spironolactone?

Alcohol can interfere with spironolactone’s activity within the body and may cause low blood pressure. You may experience headaches, dizziness, fainting, or changes in heart rate when using alcohol and spironolactone together.¹⁶

What to discuss with your doctor before starting spironolactone

Your doctor will determine if spironolactone is safe and effective for you. At your appointment, you should discuss the following topics:¹⁷

  • Other medications you are currently taking or that you occasionally take, including vitamins, herbs, supplements, and over-the-counter drugs

  • Other medical conditions you have, including kidney or liver disease, gout, and any that cause high potassium levels, such as Addison’s disease

  • Issues or allergic reactions you have had with medications in the past 

  • Your chosen method of contraception and whether you are considering becoming pregnant

  • Lifestyle choices that may affect your body’s handling of the medication (including drinking or smoking habits)

  • Any upcoming surgeries or dental procedures

Stopping spironolactone

If your doctor advises you to stop taking spironolactone, stopping shouldn’t cause any problems. However, you should not discontinue it without your doctor’s guidance. Some people must gradually reduce their dosage over several weeks to avoid adverse effects.

Drug approval history

1957: Spironolactone was first developed.¹⁸

1960: Spironolactone tablets earned US FDA approval.¹⁹

2017: The US FDA approved CaroSpir, the first liquid form of spironolactone.²⁰

Tips for taking spironolactone

The following tips can help you take spironolactone safely while maximizing the drug’s effectiveness:

  • Always discuss any side effects with your doctor.

  • Take spironolactone with food if the medication upsets your stomach.

  • Try to take your medication at about the same time every day.

  • Avoid potassium supplements and foods that are high in potassium.

  • If you see other healthcare professionals, including specialist doctors or nurses, let them know you’re taking spironolactone, as it can affect the results of certain lab tests.

  • Store your medication in a dark, cool, and dry place.

  • Avoid driving until you know how this medicine affects you.

Frequently asked questions

Will spironolactone affect my weight?

You may experience a minor weight loss because the medication causes your body to lose more water, but your change in weight should not be significant. Speak with your doctor if you lose a significant amount of weight quickly, as this may be a sign of dehydration.

Can I drive while taking spironolactone?

Spironolactone shouldn’t prevent you from driving once you understand how it affects you. Some people may feel tired or dizzy, but these effects are most commonly associated with the initiation of treatment or an increase in dosage.

Should I avoid certain foods while taking spironolactone?

Spironolactone may cause high potassium levels in the blood, so your doctor may recommend avoiding high-potassium foods or supplements. Speak with your doctor about any dietary changes and limitations you may need to consider while taking spironolactone.

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Disclaimer

Here at HealthMatch, we’ve done our best to ensure that the information provided in this article is helpful, up to date, and, most importantly, accurate.

However, we can’t replace the one-to-one advice of a qualified medical practitioner or outline all of the possible risks associated with this particular drug and your circumstances.

It is therefore important for you to note that the information contained in this article does not constitute professional medical or healthcare advice, diagnosis or recommendation of treatment and is not intended to, nor should be used to, replace professional medical advice. This article may not always be up to date and is not exhaustive of all of the risks and considerations relevant to this particular drug. In no circumstances should this article be relied upon without independent consideration and confirmation by a qualified medical practitioner.

Your doctor will be able to explain all possible uses, dosages, precautions, interactions with other drugs, and other potential adverse effects, and you should always talk to them about any kind of medication you are taking, thinking about taking or wanting to stop taking.

Curious about clinical trials?

Access the latest treatments and medications. unavailable elsewhere - entirely free of charge. We make it easy to take part.