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Diuretic medicines
9-minute read
Key facts
- Diuretic medicines help your kidneys produce more urine, removing extra fluid from your body.
- Diuretics can help lower blood pressure and reduce fluid build-up caused by heart, liver or kidney problems.
- Diuretics can cause an imbalance of fluid and salts in your blood — see your doctor regularly to check your levels.
- There are several types of diuretics, including thiazide, loop, potassium-sparing and others.
- Always follow your doctor's advice before stopping or changing your dose.
What are diuretics?
Diuretics are medicines that make your kidneys produce more urine. Urine contains water and electrolytes (salts). Diuretics help remove extra fluid in your body. Some people call them:
- fluid or water tablets
- fluid retention tablets
- water retention tablets
There are several types of diuretics, including:
- thiazide
- loop
- potassium-sparing
These act in different parts of your kidney, affecting your body in different ways.
What are diuretics used for?
Diuretics are commonly used to treat high blood pressure (hypertension).
They are also used to treat fluid retention due to:
They can relieve symptoms of oedema (swelling or fluid retention) in your legs, lungs or abdomen.
Some people can stop taking diuretics once their symptoms improve. Others need to keep taking them.
Diuretics are usually prescribed with other medicines used to treat high blood pressure or heart failure.
How do diuretics work?
Your kidneys manage the amount of water and electrolytes (also known as 'salts') in your blood. Diuretics make your kidneys release more electrolytes into your urine. This makes your kidneys release water, producing more urine and getting rid of extra fluid.
Diuretics cause you to lose electrolytes through your urine. Your doctor may request regular blood tests to monitor electrolyte levels in your blood.
What types of diuretics might I be prescribed?
You can only get a diuretic with a prescription from your doctor.
Thiazide diuretics
Common thiazide and thiazide-related diuretics include hydrochlorothiazide and indapamide. You might take these for high blood pressure. These medicines are thought to relax your blood vessels, lowering your blood pressure.
Thiazide diuretics are often combined with other blood pressure medicines — sometimes in the same tablet.
Loop diuretics
The most common loop diuretic is furosemide (or frusemide). Loop diuretics have rapid diuretic effects, working for 4 to 6 hours after you take the medicine. Your doctor might prescribe this if you have heart failure causing shortness of breath.
Potassium-sparing diuretics
Spironolactone is an example of a potassium-sparing diuretic. As well as treating high blood pressure or fluid retention, it might be prescribed to increase your potassium levels. It is also used for some hormonal problems including certain types of acne.
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What are the side effects or risks of diuretics?
Seek medical help immediately if you take diuretics and you faint, feel very dizzy, confused or weak or if you develop heart palpitations.
Diuretics can cause an imbalance of salts in your blood. Some cause low potassium while others cause high potassium. They can also affect your levels of:
Your doctor will monitor the levels of these substances in your body while you are taking diuretics.
If you take too much of a diuretic medicine, it may cause:
- kidney damage
- low blood pressure
- dehydration
If you have any of these problems, you may experience:
If you feel dizzy, take care to stand up slowly.
In severe cases, diuretics can cause confusion or unconsciousness.
Other side effects of some diuretics include:
- hearing loss
- vision impairment
- jaundice and skin conditions
- abdominal (belly) pain, chest pain or palpitations
- diabetes
- gout
- breast enlargement
Some medicines and supplements can affect how diuretics work. If you take any other medicines or over-the-counter supplements, always tell your pharmacist that you use diuretics. They can help you to select the correct medicines for your circumstances.
Tell your doctor if you have side effects. If they are caused by a fluid or electrolyte imbalance, your doctor can adjust your dose. Don't stop taking your medicine or change your dose unless your doctor advises you to.
Who should not use diuretics?
Avoid taking diuretics if you:
- are pregnant or breastfeeding
- have severe kidney or liver problems
You will need extra careful monitoring if you:
- are older
- take non-steroidal anti-inflammatory medicines
- have low blood pressure
- have gout or diabetes
- have difficulty passing urine
Always take diuretics as instructed by your doctor. Do not stop taking them unless you have been advised by a health professional to do so.
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How should I take my diuretic medicine?
Seek medical help immediately if you take diuretics and you faint, dizzy, confused or weak or develop heart palpitations.
Make sure to take your diuretics based on your doctor's and pharmacist's instructions.
When taking diuretics try to maintain healthy levels of fluid and electrolytes. Ask your doctor how much water and salt you should have in your diet each day if you take diuretics. You may need to limit salt in your diet or weigh yourself daily.
If you take loop diuretics, you might need to eat foods that are high in potassium, such as bananas and tomatoes. If you take potassium-sparing diuretics, you might need to avoid these foods. Always talk to your doctor about any changes you make to your diet when taking diuretics or any other regular medicines.
Tell your doctor if you're having trouble keeping up your fluids, for example, if you have diarrhoea. They may tell you not to take your diuretic until you get better.
Diuretics can make you urinate (wee) more often. Try to take your diuretics early in the day to avoid having to pass urine during the night.
When should I see my doctor?
It's important to see your doctor regularly. They can:
- monitor your fluid levels
- arrange blood tests to check your kidney function and electrolyte levels
- adjust your dose if needed
See your doctor within 2 weeks after starting a diuretic or changing your dose. If your dose is changed in hospital, see your doctor within a week after going home.
Speak to your doctor if you:
- experience side effects that trouble you
- have signs of an allergic reaction
- become pregnant, are planning a pregnancy or start breastfeeding
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Are there any alternatives to diuretics?
There are many other medicines that lower blood pressure. They work best when used in combination with healthy lifestyle changes.
Diuretics are the best treatment for symptoms of fluid retention. Some other medicines can have a diuretic effect.
You may be able to prevent extra fluid by restricting your water and salt intake. Ask your doctor if this is appropriate for you. Weighing yourself daily can alert you if fluid builds up.
Resources and support
To find out more about diuretics you can also visit these websites:
- Check out Kidney Health Australia for information about keeping your kidneys healthy.
- Visit the Heart Foundation to learn about blood pressure control and living with heart failure.
- The Liver Foundation has information about liver health.
Other languages
The Heart Foundation and Kidney Health Australia have information in several other languages.
You can find translated information on medicines on the NPS MedicineWise website.
Looking for information for Aboriginal and/or Torres Strait Islander people?
Learn about kidney health and heart health for Aboriginal and/or Torres Strait Islander people.
Read more about diuretics for treatment of your high blood pressure.