Meds and you

30 September 2013


Spironolactone is a potassium-sparing diuretic. Diuretics are drugs that increase the production of urine, thereby reducing excess water in the body.


Spironolactone is the active ingredient of Aldactone tablets (Nappi Code: 701793-007, 701807-016), Sandoz Spironolactone tablets (Nappi Code: 769665-004/012) and Spiractin tablets (Nappi Code: 765910-004/012, 898937-019).

It is also one of the active ingredients found in Aldazide tablets (Nappi Code: 701815-019).

General information
Spironolactone is a potassium-sparing diuretic. Diuretics are drugs that increase the production of urine, thereby reducing excess water in the body.

Most diuretics cause a loss of potassium from the body which may cause side effects such as muscle cramps. Spironolactone doesn't have this effect and is therefore called a potassium-sparing diuretic.

In South Africa spironolactone is registered for the treatment of oedema - an accumulation of excessive amounts of fluid in body tissue resulting in swelling - that results from conditions such as congestive heart failure and kidney or liver disorders. It is also used for the treatment of mild to moderately high blood pressure, often in combination with another diuretic or blood pressure lowering drug.

Spironolactone is not a cure for high blood pressure, but is effective in keeping it under control. For it to be effective you must take it regularly. High blood pressure declines slowly and it may take a few weeks for spironolactone to reach its full effect. Keep taking this medicine during this period, even if you are feeling better or fail to notice any improvement.

The first couple of doses of this medication may cause a sudden drop in blood pressure which may cause dizziness or blackouts when you suddenly get up. It is therefore advised that you be resting when starting treatment and to lie down for 2 hours afterwards.

The diuretic should best be taken in the morning to prevent additional night-time visits to the toilet. It is possible that you may produce a larger volume of urine at the start of treatment with spironolactone. Be aware of where your nearest ablution facilities are if you are away from home!

How does spironolactone work? Spironolactone reduces the overall fluid volume in the body by controlling the balance of salt and water in the body. This diuretic increases the elimination of salt from the blood. This salt draws water from the blood which is eliminated from the body alongside the salt.

Fast facts

Drug schedule: schedule 3
Available as: spironolactone is available as tablets.
What does it do? Spironolactone lowers blood pressure and reduces fluid volume in the body.
Overdose risk: low
Dependence risk: low
Is spironolactone available as a generic? yes
Is spironolactone available on prescription only? yes

User information

Duration of action: up to 24 hours
Dietary advice: spironolactone should best be taken with food.
Stopping this medicine: it may be dangerous to discontinue this drug abruptly as symptoms of the condition being treated may recur. Don't discontinue this drug without speaking to your doctor.
Prolonged use: prolonged use may result in an electrolyte disturbance. Kidney function may also need to be evaluated periodically.

Special precautions
Consult your doctor before using this drug if:

  • you have kidney or liver disease

  • you have known high blood levels of potassium

  • you are taking a potassium supplement

  • you have diabetes

  • you have been diagnosed with Addison’s disease

  • you are taking other medication

Pregnancy: avoid. Potential risk to the foetus has been reported. Consult your doctor before use, or if you are planning to fall pregnant.
Breastfeeding: avoid. This medication is passed through breast milk and may affect your baby adversely. Consult your doctor before use.
Porphyria: avoid. This medication may cause serious adverse effects. Consult your doctor before use.
Infants and children: a dosage reduction may be needed.
The elderly: caution is advised in the elderly as the likelihood of adverse effects is increased.
Driving and hazardous work: caution is advised as use of this medication may lead to dizziness. and light-headedness. Avoid such activities until you know how this medication affects you.
Alcohol: avoid concomitant use of alcohol with this medication.

Possible side effects

Side Effect
Consult your doctor

Only if severe
In all cases




abdominal pain






muscle cramp


increased potassium levels


breast sensitivity


breast enlargement in men




decreased libido




menstrual irregularities






Drug interactions

potassium supplements risk of potassium toxicity
ACE inhibitors i.e. enalapril, captopril, etc risk of potassium toxicity
drugs for the treatment of high blood pressure increased blood pressure lowering effects
aspirin reduced effect of spironolactone
ciclosporin risk of potassium toxicity
digoxin increased risk of digoxin toxicity
non-steroidal anti-inflammatory drugs risk of kidney damage
warfarin reduced effect or warfarin

Disease interactions
Consult your doctor before using this drug if you have kidney or liver disease, diabetes or if you have been diagnosed with Addison’s disease.

Overdose action
A small overdose is no cause for concern. In case of intentional large overdose seek emergency medical attention.

Recommended dosage
Adults: oral, 25 -200 mg/day

This material is not intended to substitute medical advice, but is for informational purposes only. Please consult a physician for specific treatment and recommendations.

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