How does this medication work? What will it do for me?

Spironolactone belongs to the class of medications known as diuretics (water pills). It is used to treat edema (fluid retention) that occurs with congestive heart failure, cirrhosis of the liver, and nephrotic syndrome. It is also used to treat high blood pressure and to diagnose and treat primary hyperaldosteronism (a condition where too much aldosterone is produced by the adrenal glands).

Spironolactone can also be used to treat or prevent hypokalemia (too little potassium in the body) when other methods are not appropriate. Spironolactone works by making the body lose excess water and salt but reduces the loss of potassium from the body.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

25 mg
Each light yellow, round, biconvex, film-coated tablet, debossed "ALDACTONE" and "25" on one face and "SEARLE" and "1001" on the other face and with peppermint odour, contains spironolactone 25 mg. Nonmedicinal ingredients: calcium sulfate, carnauba wax, cornstarch, hypromellose, magnesium stearate, opaspray M-1-2042, peppermint flavouring, polyethylene glycol 400, povidone, and stearic acid.

100 mg
Each peach, round, biconvex, scored, film-coated tablet, debossed "ALDACTONE" and "100" on one face and "SEARLE" and "1031" on the other (scored) face and with peppermint odour, contains spironolactone 100 mg. Nonmedicinal ingredients: calcium sulfate, carnauba wax, cornstarch, hypromellose, magnesium stearate, opaspray M-1-2668, peppermint flavouring, polyethylene glycol 400, povidone, and stearic acid.

How should I use this medication?

The recommended dose of spironolactone for adults ranges from 25 mg to 400 mg daily depending on the condition being treated. It is given in single or divided doses.

For children with edema (fluid retention) associated with congestive heart failure, cirrhosis of the liver, or nephritic syndrome, the daily dose is based on body weight and is given in single or divided doses.

Since this medication increases urine output, it is better to take it early in the day (with breakfast if you are taking a once-daily dose, or with breakfast and lunch if you are taking divided doses). Spironolactone may be taken with or without food. If stomach upset occurs, take the medication with food.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from heat and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Spironolactone should not be taken by anyone who:

  • is allergic to spironolactone or to any of the ingredients of the medication
  • is unable to produce urine
  • has Addison's disease
  • has high blood levels of potassium
  • has rapidly worsening kidney function
  • has significantly reduced kidney function

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • abdominal pain
  • diarrhea
  • dizziness
  • drowsiness
  • dry mouth
  • fatigue
  • fever
  • frequent urination
  • headache
  • nausea
  • thirst
  • vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • confusion
  • enlarged or painful breasts
  • fast, slow, or irregular heartbeat
  • irregular menstrual period
  • muscle weakness or cramps
  • rapid weight loss
  • shortness of breath
  • unusual bruising or bleeding
  • yellowing of the skin or eyes

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • signs of a severe allergic reaction such as difficulty breathing; hives; or swelling of the face, tongue, or throat
  • signs of stomach bleeding such as vomiting of blood, stomach pain, black and tarry stools
  • skin rash

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Breast enlargement in men: Men may develop breast enlargement with the use of spironolactone. If this occurs, tell your doctor. In the great majority of cases, breast enlargement disappears once the medication is stopped.

Drowsiness and dizziness: Spironolactone may cause drowsiness or dizziness. Do not drive or operate machinery until you know how this medication affects you. Alcohol can add to the drowsiness caused by this medication.

Potassium: This medication may cause high potassium levels if potassium intake is too high. Do not take potassium supplements, follow a diet rich in potassium, or use salt substitutes containing potassium while taking spironolactone. People with reduced kidney function, seniors, and people with diabetes are more at risk of developing high potassium levels.

Reduced liver function: People with reduced liver function should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Sodium: This medication can cause or worsen low sodium levels when given with diuretics (water pills). If you experience dry mouth, thirst, and drowsiness while taking this medication, contact your doctor.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking spironolactone, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

What other drugs could interact with this medication?

There may be an interaction between spironolactone and any of the following:

  • ACTH
  • alcohol
  • angiotensin II antagonists (e.g., candesartan, valsartan)
  • angiotensin-converting enzyme inhibitors (ACE inhibitors; e.g., captopril, enalapril, lisinopril, ramipril)
  • antipyrine
  • barbiturates (e.g., phenobarbital, butalbital)
  • cholestyramine
  • corticosteroids (e.g., prednisone, dexamethasone)
  • digoxin
  • lithium
  • narcotic medications (e.g., codeine, morphine)
  • norepinephrine
  • nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., indomethacin, mefenamic acid)
  • other diuretics (e.g., hydrochlorothiazide, triamterene)
  • other medications that reduce blood pressure
  • potassium-containing medications, supplements, or salt-substitutes (e.g., potassium chloride, potassium citrate, potassium gluconate, potassium iodide, potassium phosphate)
  • salicylates (e.g., ASA, salsalate)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.