Spironolactone

What is spironolactone?

Spironolactone is a type of medication known as a water tablet (diuretic). It helps your body get rid of extra salt and water, which can lower blood pressure and reduce fluid buildup in conditions like heart failure, liver disease, or kidney problems. 

Unlike other diuretics, spironolactone helps your body hold onto potassium, so your levels don’t drop too low. For this reason, it is sometimes given alongside these other diuretics, 

It also blocks the hormone aldosterone, which controls how much salt and water your body keeps. By blocking this hormone, spironolactone helps your body remove extra fluid while helping to keep potassium balanced[1]. 

What is spironolactone used for?

Spironolactone is prescribed for several conditions. These can include high blood pressure (hypertension), heart failure, and fluid retention (oedema) caused by liver cirrhosis, kidney disease (such as nephrotic syndrome), heart failure, or hypokalaemia where your potassium levels are too low[1]. 

In other cases, spironolactone may be prescribed for hyperaldosteronism, a condition where the adrenal glands produce too much aldosterone. It can also be used for acne and unwanted hair growth (hirsutism) in women though these are unlicensed uses[1]. 

How does spironolactone work?

Spironolactone works by blocking aldosterone receptors in the kidneys. Aldosterone normally causes the body to retain sodium and water while getting rid of potassium. But instead, by blocking this hormone, spironolactone increases the excretion of sodium and water and helps the body retain potassium. We need the right amount of potassium for our hearts to function normally. Excreting sodium and water lowers blood pressure and reduces fluid build-up in conditions like heart failure and liver disease[1]. 

Who can take spironolactone?

Spironolactone is generally safe for adults but may not be suitable for everyone. It should be avoided or used with caution in people who have kidney disease or poor kidney function, high potassium levels (hyperkalaemia), Addison’s disease, or an inability to pass urine. 

Individuals who are pregnant or breastfeeding should consult their doctor or pharmacist. Regardless of other conditions, you should always discuss with your healthcare provider before starting spironolactone[1]. 

Please tell your doctor or pharmacist about any conditions you may have before you start treatment, and always follow the instructions in the Patient Information Leaflet[2]. 

What is the typical dosage of spironolactone?

The dose of spironolactone depends on the condition being treated. It is usually taken daily, in doses ranging from 25 to 200mg (or more). Your doctor may start you on a lower dose and adjust it gradually. For safe and effective use, you should always follow the dosage instructions provided by your prescriber[1]. 

How do you take spironolactone?

Spironolactone is usually taken at the same time once or twice daily. You can take it with or without food. Swallow the tablets whole with water, and do not take more than the prescribed dose[1]. 

When taking spironolactone, you may need regular blood tests to check potassium levels and kidney function[1]. 

Can you stop taking spironolactone suddenly?

It’s important not to stop taking spironolactone without first speaking to your doctor or pharmacist. This is especially true if you are taking it for heart failure or high blood pressure, when stopping suddenly can lead to a return of fluid retention or worsening of your condition[1]. 

What should you do if you take too much spironolactone?

A spironolactone overdose can be dangerous, particularly if it leads to hyperkalaemia, or a high potassium level. This can affect your heart and your muscles. Symptoms of an overdose include but are not limited to[1]: 

• An irregular heartbeat 

• Palpitations and/or chest pains 

• Low blood pressure 

• Muscle weakness, numbness or cramping 

• Confusion, lethargy and drowsiness 

• Seizures 

• Nausea and vomiting 

• diarrhoea 

Seek emergency medical help immediately if you suspect an overdose of spironolactone. 

What should you do if you forget a dose of spironolactone?

If you forget to take a spironolactone dose, you should take the missed dose as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and continue as normal. Do not take two doses at the same time to make up for a missed one as this can cause dangerous symptoms[1]. 

Which medicines should you avoid while taking spironolactone?

You should avoid combining spironolactone with various other medicines, unless directed by your doctor. These include potassium supplements, some blood pressure medications, some pain killers (such as ibuprofen), lithium, and eplerenone[1]. 

If combined with spironolactone, these can increase the risk of high potassium levels or kidney problems.

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2]. 

What are the side effects of spironolactone?

The most common side effects of spironolactone can include increased urination, dizziness when standing up, breast tenderness or enlargement (particularly in men), and changes to menstrual periods[1]. 

More serious – but rarer – side effects of spironolactone include[1]: 

• High potassium levels, which may cause muscle weakness or a slow or irregular heartbeat 

• Kidney problems 

• Severe allergic reactions such as rash, itching, or swelling of the face or throat 

If any side effects are worrying, severe, or persistent, contact your doctor.

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice.

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Frequently asked questions about spironolactone

Can spironolactone cause weight loss? 

Spironolactone can often cause a small amount of weight loss due to fluid loss. It does not cause fat loss and it is not a weight-loss medication[1]. 

Is spironolactone safe in pregnancy? 

Generally, spironolactone is not recommended during pregnancy. You should speak to your doctor or pharmacist if you take spironolactone and are pregnant or planning to become pregnant[1]. 

Can I drink alcohol while taking spironolactone? 

Alcohol may increase the risk of dizziness and dehydration. Therefore, it is advisable to avoid or limit alcohol consumption while taking spironolactone to reduce the likelihood of these side effects[1]. 

How long does spironolactone take to work? 

After starting spironolactone, you may notice an effect on blood pressure or fluid levels within a few days to a few weeks. However, this depends on each individual and the condition being treated[1]. 

For the official NHS guide to spironolactone, visit their website.