Furosemide is strong diuretic medicine (sometimes called a 'water tablet') that is used to remove excess fluid from the body in conditions such as heart failure.

What is furosemide used for?

  • Furosemide is used to remove  excess fluid (oedema) that has been retained in the body, for example due to conditions affecting the heart (eg heart failure), lungs (eg pulmonary oedema), liver (eg cirrhosis), kidneys (eg kidney failure), or blood vessels.
  • Lowering high blood pressure (hypertension).
  • Furosemide is usually taken by mouth. It is given by injection in emergencies, when a rapid effect is required, and in cases when the medicine cannot be taken by mouth.

How does furosemide work?

  • Furosemide is a type of medicine called a loop diuretic. Diuretics are sometimes referred to as 'water tablets'. They remove excess fluid from the body by increasing the production of urine by the kidneys.
  • Loop diuretics work by causing the kidneys to increase the amount of salts such as potassium and sodium that are filtered out of the blood and into the urine.
When these salts are filtered out of the blood by the kidneys, water is also drawn alongside. As diuretics increase the removal of salts from the blood, they also cause more water to be drawn out of the blood and into the urine.
  • Furosemide is used to treat conditions where excess fluid has been retained in the body (oedema). For example, in heart failure, the pumping mechanism of the heart is less effective. This can cause fluid to build up in the ankles, causing swelling, and the lungs (pulmonary oedema), which makes it difficult to breathe. Furosemide helps the body to remove this excess fluid. Removing fluid from the blood vessels also decreases the pressure within the blood vessels. This makes it easier for a weak heart to pump blood around the body. 
  • Furosemide is also used to remove excess fluid that can accumulate in people with cirrhosis of the liver. This fluid may accumulate in the abdomen (ascites) or in the legs (peripheral oedema).
  • Problems with blood circulation in the legs can also cause fluid retention and swelling of the ankles or lower legs, and this can also be treated with furosemide.
  • At higher doses the amount of water drawn from the blood into the urine is much greater, so furosemide is also used when there is reduced production of urine in people with kidney failure.
  • As furosemide decreases the pressure within the blood vessels, it is also sometimes used to treat high blood pressure, usually when other blood pressure lowering medicines have not been effective enough.
  • What is the dose of furosemide and how often should I take it?

    • Furosemide tablets are usually taken once or twice a day.
    • The number of tablets to take and how often to take them will vary from person to person. It is important to follow the instructions given by your doctor. These will also be printed on the dispensing label that your pharmacist has put on the packet of medicine. If you are unsure about anything ask your pharmacist for advice.
    • It's usually best to take furosemide in the morning. This is because it will make you need to go to the toilet more often and taking it too late in the day can end up disturbing your sleep that night. However, you can take it at a time to suit you. For example, if you want to go out in the morning and don't want to have to find a toilet, you can delay taking your dose until later. However, it is best not to take a dose too late in the afternoon. Ask your pharmacist for more advice.
    • Keep taking the tablets as directed until your doctor tells you to stop. If you are taking them for high blood pressure you may need to keep taking them on a long-term basis. 

    Should I take furosemide with or without food?

    • Furosemide can be taken either with or without food.
    • The tablets should be swallowed with a drink of water.

    What should I do if I miss a dose of furosemide?

    • If you forget to take a dose take it as soon as you remember, unless it is nearly time for your next dose. In this case leave out the missed dose and take your next dose as usual. Don't take a double dose to make up for a missed dose.

    Side effects of furosemide

    • Decreased levels of sodium, potassium, magnesium or calcium in the blood.
    • Passing a lot of urine.
    • Low blood pressure (hypotension).
    • Dizziness.
    • Headache.
    • Weakness.
    • Drowsiness.
    • Dry mouth.
    • Feeling thirsty.
    • Dehydration.
    • Disturbances of the gut such as diarrhoea, nausea, vomiting or abdominal pain.
    • Increased blood sugar levels.
    • Increased blood uric acid level (hyperuricaemia) which may cause kidney problems or gout.
    • Rise in the levels of fats such as cholesterol in the blood.
    • Pins and needles sensations.
    • Hearing problems.
    • Sensation of ringing or other noise in the ears (tinnitus).
    • Visual disturbances.
    • Skin rashes.
    • Abnormal reaction of the skin to light, usually a rash (photosensitivity).
    • Decrease in the normal numbers of blood cells in the blood.
    • Inflammation of the pancreas (pancreatitis).

    Talk to your doctor, nurse or pharmacist or read the leaflet provided with the medicine if you want more information about the possible side effects of furosemide.